Flexible Approaches to Computing Mediated Effects in Generalized Linear Models: Generalized Estimating Equations and Bootstrapping

ERIC Educational Resources Information Center

Schluchter, Mark D.

2008-01-01

In behavioral research, interest is often in examining the degree to which the effect of an independent variable X on an outcome Y is mediated by an intermediary or mediator variable M. This article illustrates how generalized estimating equations (GEE) modeling can be used to estimate the indirect or mediated effect, defined as the amount by…

Causal Models for Mediation Analysis: An Introduction to Structural Mean Models.

PubMed

Zheng, Cheng; Atkins, David C; Zhou, Xiao-Hua; Rhew, Isaac C

2015-01-01

Mediation analyses are critical to understanding why behavioral interventions work. To yield a causal interpretation, common mediation approaches must make an assumption of "sequential ignorability." The current article describes an alternative approach to causal mediation called structural mean models (SMMs). A specific SMM called a rank-preserving model (RPM) is introduced in the context of an applied example. Particular attention is given to the assumptions of both approaches to mediation. Applying both mediation approaches to the college student drinking data yield notable differences in the magnitude of effects. Simulated examples reveal instances in which the traditional approach can yield strongly biased results, whereas the RPM approach remains unbiased in these cases. At the same time, the RPM approach has its own assumptions that must be met for correct inference, such as the existence of a covariate that strongly moderates the effect of the intervention on the mediator and no unmeasured confounders that also serve as a moderator of the effect of the intervention or the mediator on the outcome. The RPM approach to mediation offers an alternative way to perform mediation analysis when there may be unmeasured confounders.

Improving quality-of-life outcomes for patients with cancer through mediating effects of depressive symptoms and functional status: a three-path mediation model.

PubMed

Hsu, Mei-Chi; Tu, Chun-Hsien

2014-09-01

To test a hypothetical three-path mediation model evaluating the effects of functional status and depressive symptoms on the relationship between fatigue and quality of life in patients with cancer on the basis of the Theory of Unpleasant Symptoms. Patients with cancer often experience two or more concurrent, interrelated, mutually influential symptoms. Multiple unpleasant symptoms that have been proposed as mediating variables affecting quality of life in a model proposed in recent cancer studies are scanty. This study was a cross-sectional, descriptive, correlational design. Three hundred and twenty-six patients with cancer from oncology clinics were recruited in Taiwan between 2010-2011. Mediation models were tested and confirmed by applying structural modelling using Analysis of Moment Structures and the joint significance test. Fatigue affects patient quality of life directly or indirectly through functional status and depressive symptoms. These two mediating variables exhibited direct effects on quality of life. A path analysis approach revealed that 47·28 and 67·70% of the total effects of functional status and depressive symptoms, respectively, on the quality-of-life mediation models are attributable to 29·6 and 44·7% of the total effects between fatigue and quality of life, which mediated through two mediators, respectively. Quality of life may be enhanced by simultaneously improving physiological and psychological factors. An understanding of mediating effects is valuable in nursing care of patients with cancer, particularly in the early phase of treatment or in newly diagnosed stages I-III or recently treated patients with cancer in different disease stages. © 2013 John Wiley & Sons Ltd.

Depression and pain: testing of serial multiple mediators.

PubMed

Wongpakaran, Tinakon; Wongpakaran, Nahathai; Tanchakvaranont, Sitthinant; Bookkamana, Putipong; Pinyopornpanish, Manee; Wannarit, Kamonporn; Satthapisit, Sirina; Nakawiro, Daochompu; Hiranyatheb, Thanita; Thongpibul, Kulvadee

2016-01-01

Despite the fact that pain is related to depression, few studies have been conducted to investigate the variables that mediate between the two conditions. In this study, the authors explored the following mediators: cognitive function, self-sacrificing interpersonal problems, and perception of stress, and the effects they had on pain symptoms among patients with depressive disorders. An analysis was performed on the data of 346 participants with unipolar depressive disorders. The 17-item Hamilton Depression Rating Scale, Mini-Mental State Examination, the pain subscale of the health-related quality of life (SF-36), the self-sacrificing subscale of the Inventory of Interpersonal Problems, and the Perceived Stress Scale were used. Parallel multiple mediator and serial multiple mediator models were used. An alternative model regarding the effect of self-sacrificing on pain was also proposed. Perceived stress, self-sacrificing interpersonal style, and cognitive function were found to significantly mediate the relationship between depression and pain, while controlling for demographic variables. The total effect of depression on pain was significant. This model, with an additional three mediators, accounted for 15% of the explained variance in pain compared to 9% without mediators. For the alternative model, after controlling for the mediators, a nonsignificant total direct effect level of self-sacrificing was found, suggesting that the effect of self-sacrificing on pain was based only on an indirect effect and that perceived stress was found to be the strongest mediator. Serial mediation may help us to see how depression and pain are linked and what the fundamental mediators are in the chain. No significant, indirect effect of self-sacrificing on pain was observed, if perceived stress was not part of the depression and/or cognitive function mediational chain. The results shown here have implications for future research, both in terms of testing the model and in clinical application.

Causal mediation analysis with a latent mediator.

PubMed

Albert, Jeffrey M; Geng, Cuiyu; Nelson, Suchitra

2016-05-01

Health researchers are often interested in assessing the direct effect of a treatment or exposure on an outcome variable, as well as its indirect (or mediation) effect through an intermediate variable (or mediator). For an outcome following a nonlinear model, the mediation formula may be used to estimate causally interpretable mediation effects. This method, like others, assumes that the mediator is observed. However, as is common in structural equations modeling, we may wish to consider a latent (unobserved) mediator. We follow a potential outcomes framework and assume a generalized structural equations model (GSEM). We provide maximum-likelihood estimation of GSEM parameters using an approximate Monte Carlo EM algorithm, coupled with a mediation formula approach to estimate natural direct and indirect effects. The method relies on an untestable sequential ignorability assumption; we assess robustness to this assumption by adapting a recently proposed method for sensitivity analysis. Simulation studies show good properties of the proposed estimators in plausible scenarios. Our method is applied to a study of the effect of mother education on occurrence of adolescent dental caries, in which we examine possible mediation through latent oral health behavior. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Exploring the Relationship Between Social Anxiety and Bulimic Symptoms: Mediational Effects of Perfectionism Among Females

PubMed Central

Menatti, Andrew R.; Weeks, Justin W.; Levinson, Cheri A.; McGowan, Maggie M.

2013-01-01

Previous findings indicate that social anxiety and bulimia co-occur at high rates; one mechanism that has been proposed to link these symptom clusters is perfectionism. We tested meditational models among 167 female undergraduates in which maladaptive evaluative perfectionism concerns (MEPC; i.e., critical self-evaluative perfectionism) mediated the relationship between social anxiety and bulimic symptoms. Results from a first model indicated that MEPC mediated the relationship between fear of public scrutiny and bulimia symptoms. This indirect effect was significant above and beyond the indirect effects of maladaptive body-image cognitions and perfectionism specific to pure personal standards. A second model was tested with MEPC mediating the relationship between social interaction anxiety and bulimia symptoms. Similar results were obtained; however, in this model, a significant direct effect remained after partialing out the indirect effect of the mediators. Theoretical implications are discussed. PMID:24932054

A General Model for Testing Mediation and Moderation Effects

PubMed Central

MacKinnon, David P.

2010-01-01

This paper describes methods for testing mediation and moderation effects in a dataset, both together and separately. Investigations of this kind are especially valuable in prevention research to obtain information on the process by which a program achieves its effects and whether the program is effective for subgroups of individuals. A general model that simultaneously estimates mediation and moderation effects is presented, and the utility of combining the effects into a single model is described. Possible effects of interest in the model are explained, as are statistical methods to assess these effects. The methods are further illustrated in a hypothetical prevention program example. PMID:19003535

Cross-Sectional Analysis of Longitudinal Mediation Processes.

PubMed

O'Laughlin, Kristine D; Martin, Monica J; Ferrer, Emilio

2018-01-01

Statistical mediation analysis can help to identify and explain the mechanisms behind psychological processes. Examining a set of variables for mediation effects is a ubiquitous process in the social sciences literature; however, despite evidence suggesting that cross-sectional data can misrepresent the mediation of longitudinal processes, cross-sectional analyses continue to be used in this manner. Alternative longitudinal mediation models, including those rooted in a structural equation modeling framework (cross-lagged panel, latent growth curve, and latent difference score models) are currently available and may provide a better representation of mediation processes for longitudinal data. The purpose of this paper is twofold: first, we provide a comparison of cross-sectional and longitudinal mediation models; second, we advocate using models to evaluate mediation effects that capture the temporal sequence of the process under study. Two separate empirical examples are presented to illustrate differences in the conclusions drawn from cross-sectional and longitudinal mediation analyses. Findings from these examples yielded substantial differences in interpretations between the cross-sectional and longitudinal mediation models considered here. Based on these observations, researchers should use caution when attempting to use cross-sectional data in place of longitudinal data for mediation analyses.

School Processes Mediate School Compositional Effects: Model Specification and Estimation

ERIC Educational Resources Information Center

Liu, Hongqiang; Van Damme, Jan; Gielen, Sarah; Van Den Noortgate, Wim

2015-01-01

School composition effects have been consistently verified, but few studies ever attempted to study how school composition affects school achievement. Based on prior research findings, we employed multilevel mediation modeling to examine whether school processes mediate the effect of school composition upon school outcomes based on the data of 28…

Predicting the F(ab)-mediated effect of monoclonal antibodies in vivo by combining cell-level kinetic and pharmacokinetic modelling.

PubMed

Krippendorff, Ben-Fillippo; Oyarzún, Diego A; Huisinga, Wilhelm

2012-04-01

Cell-level kinetic models for therapeutically relevant processes increasingly benefit the early stages of drug development. Later stages of the drug development processes, however, rely on pharmacokinetic compartment models while cell-level dynamics are typically neglected. We here present a systematic approach to integrate cell-level kinetic models and pharmacokinetic compartment models. Incorporating target dynamics into pharmacokinetic models is especially useful for the development of therapeutic antibodies because their effect and pharmacokinetics are inherently interdependent. The approach is illustrated by analysing the F(ab)-mediated inhibitory effect of therapeutic antibodies targeting the epidermal growth factor receptor. We build a multi-level model for anti-EGFR antibodies by combining a systems biology model with in vitro determined parameters and a pharmacokinetic model based on in vivo pharmacokinetic data. Using this model, we investigated in silico the impact of biochemical properties of anti-EGFR antibodies on their F(ab)-mediated inhibitory effect. The multi-level model suggests that the F(ab)-mediated inhibitory effect saturates with increasing drug-receptor affinity, thereby limiting the impact of increasing antibody affinity on improving the effect. This indicates that observed differences in the therapeutic effects of high affinity antibodies in the market and in clinical development may result mainly from Fc-mediated indirect mechanisms such as antibody-dependent cell cytotoxicity.

Monte Carlo based statistical power analysis for mediation models: methods and software.

PubMed

Zhang, Zhiyong

2014-12-01

The existing literature on statistical power analysis for mediation models often assumes data normality and is based on a less powerful Sobel test instead of the more powerful bootstrap test. This study proposes to estimate statistical power to detect mediation effects on the basis of the bootstrap method through Monte Carlo simulation. Nonnormal data with excessive skewness and kurtosis are allowed in the proposed method. A free R package called bmem is developed to conduct the power analysis discussed in this study. Four examples, including a simple mediation model, a multiple-mediator model with a latent mediator, a multiple-group mediation model, and a longitudinal mediation model, are provided to illustrate the proposed method.

Developing models of how cognitive improvements change functioning: Mediation, moderation and moderated mediation

PubMed Central

Wykes, Til; Reeder, Clare; Huddy, Vyv; Taylor, Rumina; Wood, Helen; Ghirasim, Natalia; Kontis, Dimitrios; Landau, Sabine

2012-01-01

Background Cognitive remediation (CRT) affects functioning but the extent and type of cognitive improvements necessary are unknown. Aim To develop and test models of how cognitive improvement transfers to work behaviour using the data from a current service. Method Participants (N49) with a support worker and a paid or voluntary job were offered CRT in a Phase 2 single group design with three assessments: baseline, post therapy and follow-up. Working memory, cognitive flexibility, planning and work outcomes were assessed. Results Three models were tested (mediation — cognitive improvements drive functioning improvement; moderation — post treatment cognitive level affects the impact of CRT on functioning; moderated mediation — cognition drives functioning improvements only after a certain level is achieved). There was evidence of mediation (planning improvement associated with improved work quality). There was no evidence that cognitive flexibility (total Wisconsin Card Sorting Test errors) and working memory (Wechsler Adult Intelligence Scale III digit span) mediated work functioning despite significant effects. There was some evidence of moderated mediation for planning improvement if participants had poorer memory and/or made fewer WCST errors. The total CRT effect on work quality was d = 0.55, but the indirect (planning-mediated CRT effect) was d = 0.082 Conclusion Planning improvements led to better work quality but only accounted for a small proportion of the total effect on work outcome. Other specific and non-specific effects of CRT and the work programme are likely to account for some of the remaining effect. This is the first time complex models have been tested and future Phase 3 studies need to further test mediation and moderated mediation models. PMID:22503640

Mediation analysis with time varying exposures and mediators

PubMed Central

VanderWeele, Tyler J.; Tchetgen Tchetgen, Eric J.

2016-01-01

Summary In this paper we consider causal mediation analysis when exposures and mediators vary over time. We give non-parametric identification results, discuss parametric implementation, and also provide a weighting approach to direct and indirect effects based on combining the results of two marginal structural models. We also discuss how our results give rise to a causal interpretation of the effect estimates produced from longitudinal structural equation models. When there are time-varying confounders affected by prior exposure and mediator, natural direct and indirect effects are not identified. However, we define a randomized interventional analogue of natural direct and indirect effects that are identified in this setting. The formula that identifies these effects we refer to as the “mediational g-formula.” When there is no mediation, the mediational g-formula reduces to Robins’ regular g-formula for longitudinal data. When there are no time-varying confounders affected by prior exposure and mediator values, then the mediational g-formula reduces to a longitudinal version of Pearl’s mediation formula. However, the mediational g-formula itself can accommodate both mediation and time-varying confounders and constitutes a general approach to mediation analysis with time-varying exposures and mediators. PMID:28824285

Mediation analysis with time varying exposures and mediators.

PubMed

VanderWeele, Tyler J; Tchetgen Tchetgen, Eric J

2017-06-01

In this paper we consider causal mediation analysis when exposures and mediators vary over time. We give non-parametric identification results, discuss parametric implementation, and also provide a weighting approach to direct and indirect effects based on combining the results of two marginal structural models. We also discuss how our results give rise to a causal interpretation of the effect estimates produced from longitudinal structural equation models. When there are time-varying confounders affected by prior exposure and mediator, natural direct and indirect effects are not identified. However, we define a randomized interventional analogue of natural direct and indirect effects that are identified in this setting. The formula that identifies these effects we refer to as the "mediational g-formula." When there is no mediation, the mediational g-formula reduces to Robins' regular g-formula for longitudinal data. When there are no time-varying confounders affected by prior exposure and mediator values, then the mediational g-formula reduces to a longitudinal version of Pearl's mediation formula. However, the mediational g-formula itself can accommodate both mediation and time-varying confounders and constitutes a general approach to mediation analysis with time-varying exposures and mediators.

Causal mediation analysis for longitudinal data with exogenous exposure

PubMed Central

Bind, M.-A. C.; Vanderweele, T. J.; Coull, B. A.; Schwartz, J. D.

2016-01-01

Mediation analysis is a valuable approach to examine pathways in epidemiological research. Prospective cohort studies are often conducted to study biological mechanisms and often collect longitudinal measurements on each participant. Mediation formulae for longitudinal data have been developed. Here, we formalize the natural direct and indirect effects using a causal framework with potential outcomes that allows for an interaction between the exposure and the mediator. To allow different types of longitudinal measures of the mediator and outcome, we assume two generalized mixed-effects models for both the mediator and the outcome. The model for the mediator has subject-specific random intercepts and random exposure slopes for each cluster, and the outcome model has random intercepts and random slopes for the exposure, the mediator, and their interaction. We also expand our approach to settings with multiple mediators and derive the mediated effects, jointly through all mediators. Our method requires the absence of time-varying confounding with respect to the exposure and the mediator. This assumption is achieved in settings with exogenous exposure and mediator, especially when exposure and mediator are not affected by variables measured at earlier time points. We apply the methodology to data from the Normative Aging Study and estimate the direct and indirect effects, via DNA methylation, of air pollution, and temperature on intercellular adhesion molecule 1 (ICAM-1) protein levels. Our results suggest that air pollution and temperature have a direct effect on ICAM-1 protein levels (i.e. not through a change in ICAM-1 DNA methylation) and that temperature has an indirect effect via a change in ICAM-1 DNA methylation. PMID:26272993

Mediators of the relationship between thin-ideal internalization and body dissatisfaction in the natural environment.

PubMed

Fitzsimmons-Craft, Ellen E; Bardone-Cone, Anna M; Crosby, Ross D; Engel, Scott G; Wonderlich, Stephen A; Bulik, Cynthia M

2016-09-01

Social comparisons (i.e., body, eating, exercise) and body surveillance were tested as mediators of the thin-ideal internalization-body dissatisfaction relationship using ecological momentary assessment (EMA). Participants were 232 college women who completed a 2-week EMA protocol, responding to questions three times per day. Multilevel path analysis was used to examine a 2-1-1 mediation model (thin-ideal internalization assessed as trait; between-person effects examined) and a 1-1-1 model (component of thin-ideal internalization [thin-ideal importance] assessed momentarily; within- and between-person effects examined). For the 2-1-1 model, only body comparison and body surveillance were significant specific mediators of the between-person effect. For the 1-1-1 model, all four variables were significant specific mediators of the within-person effect. Only body comparison was a significant specific mediator of the between-person effect. At the state level, many processes explain the thin-ideal internalization-body dissatisfaction relationship. However, at the trait level, body comparison and body surveillance are more important explanatory factors. Copyright © 2016 Elsevier Ltd. All rights reserved.

Mediators of the Relationship Between Thin-Ideal Internalization and Body Dissatisfaction in the Natural Environment

PubMed Central

Fitzsimmons-Craft, Ellen E.; Bardone-Cone, Anna M.; Crosby, Ross D.; Engel, Scott G.; Wonderlich, Stephen A.; Bulik, Cynthia M.

2016-01-01

Social comparisons (i.e., body, eating, exercise) and body surveillance were tested as mediators of the thin-ideal internalization-body dissatisfaction relationship using ecological momentary assessment (EMA). Participants were 232 college women who completed a 2-week EMA protocol, responding to questions three times per day. Multilevel path analysis was used to examine a 2-1-1 mediation model (thin-ideal internalization assessed as trait; between-person effects examined) and a 1-1-1 model (component of thin-ideal internalization [thin-ideal importance] assessed momentarily; within- and between-person effects examined). For the 2-1-1 model, only body comparison and body surveillance were significant specific mediators of the between-person effect. For the 1-1-1 model, all four variables were significant specific mediators of the within-person effect. Only body comparison was a significant specific mediator of the between-person effect. At the state level, many processes explain the thin-ideal internalization-body dissatisfaction relationship. However, at the trait level, body comparison and body surveillance are more important explanatory factors. PMID:27391791

POWER ANALYSIS FOR COMPLEX MEDIATIONAL DESIGNS USING MONTE CARLO METHODS

PubMed Central

Thoemmes, Felix; MacKinnon, David P.; Reiser, Mark R.

2013-01-01

Applied researchers often include mediation effects in applications of advanced methods such as latent variable models and linear growth curve models. Guidance on how to estimate statistical power to detect mediation for these models has not yet been addressed in the literature. We describe a general framework for power analyses for complex mediational models. The approach is based on the well known technique of generating a large number of samples in a Monte Carlo study, and estimating power as the percentage of cases in which an estimate of interest is significantly different from zero. Examples of power calculation for commonly used mediational models are provided. Power analyses for the single mediator, multiple mediators, three-path mediation, mediation with latent variables, moderated mediation, and mediation in longitudinal designs are described. Annotated sample syntax for Mplus is appended and tabled values of required sample sizes are shown for some models. PMID:23935262

Mediating mechanisms of a military Web-based alcohol intervention.

PubMed

Williams, Jason; Herman-Stahl, Mindy; Calvin, Sara L; Pemberton, Michael; Bradshaw, Michael

2009-03-01

This study explored the mediating mechanisms of two Web-based alcohol interventions in a sample of active duty United States military personnel. Personnel were recruited from eight bases and received the Drinker's Check-Up (N=1483), Alcohol Savvy (N=688), or served as controls (N=919). The interventions drew on motivational interviewing and social learning theory and targeted multiple mediators including social norms, perceived risks and benefits, readiness to change, and coping strategies. Baseline data were collected prior to the intervention and follow-up data on alcohol consumption were gathered 1 month and 6 months after program completion. Two mediation models were examined: (1) a longitudinal two-wave model with outcomes and mediators assessed concurrently at the 1-month follow-up; and (2) a three-wave model in which the causal chain was fully lagged. Results indicated strong support for the role of perceived descriptive norms in transmitting the effects of the Drinker's Check-Up, with consistent mediation across the majority of alcohol outcome measures for both the concurrent and fully lagged mediation models. These results suggest that web-based interventions that are effective in lowering perceived norms about the frequency and quantity of drinking may be a viable strategy for reducing alcohol consumption in military populations. The results did not support program mediation by the other targeted variables, indicating the need for future research on the effective components of alcohol interventions. The mediation models also suggest reasons why program effects were not found for some outcomes or were different across programs.

Dose- and time-dependence of the host-mediated response to paclitaxel therapy: a mathematical modeling approach.

PubMed

Benguigui, Madeleine; Alishekevitz, Dror; Timaner, Michael; Shechter, Dvir; Raviv, Ziv; Benzekry, Sebastien; Shaked, Yuval

2018-01-05

It has recently been suggested that pro-tumorigenic host-mediated processes induced in response to chemotherapy counteract the anti-tumor activity of therapy, and thereby decrease net therapeutic outcome. Here we use experimental data to formulate a mathematical model describing the host response to different doses of paclitaxel (PTX) chemotherapy as well as the duration of the response. Three previously described host-mediated effects are used as readouts for the host response to therapy. These include the levels of circulating endothelial progenitor cells in peripheral blood and the effect of plasma derived from PTX-treated mice on migratory and invasive properties of tumor cells in vitro . A first set of mathematical models, based on basic principles of pharmacokinetics/pharmacodynamics, did not appropriately describe the dose-dependence and duration of the host response regarding the effects on invasion. We therefore provide an alternative mathematical model with a dose-dependent threshold, instead of a concentration-dependent one, that describes better the data. This model is integrated into a global model defining all three host-mediated effects. It not only precisely describes the data, but also correctly predicts host-mediated effects at different doses as well as the duration of the host response. This mathematical model may serve as a tool to predict the host response to chemotherapy in cancer patients, and therefore may be used to design chemotherapy regimens with improved therapeutic outcome by minimizing host mediated effects.

Causal mediation analysis for longitudinal data with exogenous exposure.

PubMed

Bind, M-A C; Vanderweele, T J; Coull, B A; Schwartz, J D

2016-01-01

Mediation analysis is a valuable approach to examine pathways in epidemiological research. Prospective cohort studies are often conducted to study biological mechanisms and often collect longitudinal measurements on each participant. Mediation formulae for longitudinal data have been developed. Here, we formalize the natural direct and indirect effects using a causal framework with potential outcomes that allows for an interaction between the exposure and the mediator. To allow different types of longitudinal measures of the mediator and outcome, we assume two generalized mixed-effects models for both the mediator and the outcome. The model for the mediator has subject-specific random intercepts and random exposure slopes for each cluster, and the outcome model has random intercepts and random slopes for the exposure, the mediator, and their interaction. We also expand our approach to settings with multiple mediators and derive the mediated effects, jointly through all mediators. Our method requires the absence of time-varying confounding with respect to the exposure and the mediator. This assumption is achieved in settings with exogenous exposure and mediator, especially when exposure and mediator are not affected by variables measured at earlier time points. We apply the methodology to data from the Normative Aging Study and estimate the direct and indirect effects, via DNA methylation, of air pollution, and temperature on intercellular adhesion molecule 1 (ICAM-1) protein levels. Our results suggest that air pollution and temperature have a direct effect on ICAM-1 protein levels (i.e. not through a change in ICAM-1 DNA methylation) and that temperature has an indirect effect via a change in ICAM-1 DNA methylation. © The Author 2015. Published by Oxford University Press. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Rumination mediates the prospective effect of low self-esteem on depression: a five-wave longitudinal study.

PubMed

Kuster, Farah; Orth, Ulrich; Meier, Laurenz L

2012-06-01

Previous research supports the vulnerability model of low self-esteem and depression, which states that low self-esteem operates as a prospective risk factor for depression. However, it is unclear which processes mediate the effect of low self-esteem. To test for the mediating effect of rumination, the authors used longitudinal mediation models, which included exclusively prospective effects and controlled for autoregressive effects of the constructs. Data came from 663 individuals (aged 16 to 62 years), who were assessed 5 times over an 8-month period. The results indicated that low self-esteem predicted subsequent rumination, which in turn predicted subsequent depression, and that rumination partially mediated the prospective effect of low self-esteem on depression. These findings held for both men and women, and for both affective-cognitive and somatic symptoms of depression. Future studies should test for the mediating effects of additional intrapersonal and interpersonal processes.

The applied model of imagery use: Examination of moderation and mediation effects.

PubMed

Koehn, S; Stavrou, N A M; Young, J A; Morris, T

2016-08-01

The applied model of mental imagery use proposed an interaction effect between imagery type and imagery ability. This study had two aims: (a) the examination of imagery ability as a moderating variable between imagery type and dispositional flow, and (b) the testing of alternative mediation models. The sample consisted of 367 athletes from Scotland and Australia, who completed the Sport Imagery Questionnaire, Sport Imagery Ability Questionnaire, and Dispositional Flow Scale-2. Hierarchical regression analysis showed direct effects of imagery use and imagery ability on flow, but no significant interaction. Mediation analysis revealed a significant indirect path, indicating a partially mediated relationship (P = 0.002) between imagery use, imagery ability, and flow. Partial mediation was confirmed when the effect of cognitive imagery use and cognitive imagery ability was tested, and a full mediation model was found between motivational imagery use, motivational imagery ability, and flow. The results are discussed in conjunction with potential future research directions on advancing theory and applications. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Evaluating mediation and moderation effects in school psychology: A presentation of methods and review of current practice

PubMed Central

Fairchild, Amanda J.; McQuillin, Samuel D.

2017-01-01

Third variable effects elucidate the relation between two other variables, and can describe why they are related or under what conditions they are related. This article demonstrates methods to analyze two third-variable effects: moderation and mediation. The utility of examining moderation and mediation effects in school psychology is described and current use of the analyses in applied school psychology research is reviewed and evaluated. Proper statistical methods to test the effects are presented, and different effect size measures for the models are provided. Extensions of the basic moderator and mediator models are also described. PMID:20006988

Evaluating mediation and moderation effects in school psychology: a presentation of methods and review of current practice.

PubMed

Fairchild, Amanda J; McQuillin, Samuel D

2010-02-01

Third variable effects elucidate the relation between two other variables, and can describe why they are related or under what conditions they are related. This article demonstrates methods to analyze two third-variable effects: moderation and mediation. The utility of examining moderation and mediation effects in school psychology is described and current use of the analyses in applied school psychology research is reviewed and evaluated. Proper statistical methods to test the effects are presented, and different effect size measures for the models are provided. Extensions of the basic moderator and mediator models are also described.

Two-condition within-participant statistical mediation analysis: A path-analytic framework.

PubMed

Montoya, Amanda K; Hayes, Andrew F

2017-03-01

Researchers interested in testing mediation often use designs where participants are measured on a dependent variable Y and a mediator M in both of 2 different circumstances. The dominant approach to assessing mediation in such a design, proposed by Judd, Kenny, and McClelland (2001), relies on a series of hypothesis tests about components of the mediation model and is not based on an estimate of or formal inference about the indirect effect. In this article we recast Judd et al.'s approach in the path-analytic framework that is now commonly used in between-participant mediation analysis. By so doing, it is apparent how to estimate the indirect effect of a within-participant manipulation on some outcome through a mediator as the product of paths of influence. This path-analytic approach eliminates the need for discrete hypothesis tests about components of the model to support a claim of mediation, as Judd et al.'s method requires, because it relies only on an inference about the product of paths-the indirect effect. We generalize methods of inference for the indirect effect widely used in between-participant designs to this within-participant version of mediation analysis, including bootstrap confidence intervals and Monte Carlo confidence intervals. Using this path-analytic approach, we extend the method to models with multiple mediators operating in parallel and serially and discuss the comparison of indirect effects in these more complex models. We offer macros and code for SPSS, SAS, and Mplus that conduct these analyses. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

Mediation Analysis with Survival Outcomes: Accelerated Failure Time vs. Proportional Hazards Models.

PubMed

Gelfand, Lois A; MacKinnon, David P; DeRubeis, Robert J; Baraldi, Amanda N

2016-01-01

Survival time is an important type of outcome variable in treatment research. Currently, limited guidance is available regarding performing mediation analyses with survival outcomes, which generally do not have normally distributed errors, and contain unobserved (censored) events. We present considerations for choosing an approach, using a comparison of semi-parametric proportional hazards (PH) and fully parametric accelerated failure time (AFT) approaches for illustration. We compare PH and AFT models and procedures in their integration into mediation models and review their ability to produce coefficients that estimate causal effects. Using simulation studies modeling Weibull-distributed survival times, we compare statistical properties of mediation analyses incorporating PH and AFT approaches (employing SAS procedures PHREG and LIFEREG, respectively) under varied data conditions, some including censoring. A simulated data set illustrates the findings. AFT models integrate more easily than PH models into mediation models. Furthermore, mediation analyses incorporating LIFEREG produce coefficients that can estimate causal effects, and demonstrate superior statistical properties. Censoring introduces bias in the coefficient estimate representing the treatment effect on outcome-underestimation in LIFEREG, and overestimation in PHREG. With LIFEREG, this bias can be addressed using an alternative estimate obtained from combining other coefficients, whereas this is not possible with PHREG. When Weibull assumptions are not violated, there are compelling advantages to using LIFEREG over PHREG for mediation analyses involving survival-time outcomes. Irrespective of the procedures used, the interpretation of coefficients, effects of censoring on coefficient estimates, and statistical properties should be taken into account when reporting results.

Attentional control mediates the effect of social anxiety on positive affect☆

PubMed Central

Morrison, Amanda S.; Heimberg, Richard G.

2015-01-01

The goal of the present studies was to examine whether attentional control, a self-regulatory attentional mechanism, mediates the effect of social anxiety on positive affect. We tested this mediation in two studies using undergraduate students selected to represent a broad range of severity of social anxiety. Self-report assessments of social anxiety, attentional control, and positive affect were collected in a cross-sectional design (Study 1) and in a longitudinal design with three assessment points (Study 2). Results of both studies supported the hypothesized mediational model. Specifically, social anxiety was inversely related to attentional control, which itself positively predicted positive affect. This mediation remained significant even when statistically controlling for the effects of depression. Additionally, the hypothesized model provided superior model fit to theoretically-grounded equivalent models in both studies. Implications of these findings for understanding diminished positive affect in social anxiety are discussed. PMID:23254261

A mediator effect size in randomized clinical trials.

PubMed

Kraemer, Helena Chmura

2014-12-01

To understand the process by which a treatment (T) achieves an effect on outcome (O) and thus to improve the effect of T on O, it is vital to detect mediators, to compare the impact of different mediators, and to develop hypotheses about the causal factors (all mediators) linking T and O. An index is needed to facilitate interpretation of the potential clinical importance of a mediator (M) of choice of T on treatment O in randomized clinical trials (RCTs). Ideally such a mediator effect size should (1) be invariant under any rescaling of M and O consistent with the model used, and (2) reflect the difference between the overall observed effect of T on O and what the maximal effect of T on O could be were the association between T and M broken. A mediator effect size is derived first for the traditional linear model, and then more generally for any categorical (ordered or non-ordered) potential mediator. Issues such as the problem of multiple treatments, outcomes and mediators, and of causal inferences, and the correspondence between this approach and earlier ones, are discussed. Illustrations are given of the application of the approach. Copyright © 2014 John Wiley & Sons, Ltd.

Consumer-mediated recycling and cascading trophic interactions.

PubMed

Leroux, Shawn J; Loreau, Michel

2010-07-01

Cascading trophic interactions mediated by consumers are complex phenomena, which encompass many direct and indirect effects. Nonetheless, most experiments and theory on the topic focus uniquely on the indirect, positive effects of predators on producers via regulation of herbivores. Empirical research in aquatic ecosystems, however, demonstrate that the indirect, positive effects of consumer-mediated recycling on primary producer stocks may be larger than the effects of herbivore regulation, particularly when predators have access to alternative prey. We derive an ecosystem model with both recipient- and donor-controlled trophic relationships to test the conditions of four hypotheses generated from recent empirical work on the role of consumer-mediated recycling in cascading trophic interactions. Our model predicts that predator regulation of herbivores will have larger, positive effects on producers than consumer-mediated recycling in most cases but that consumer-mediated recycling does generally have a positive effect on producer stocks. We demonstrate that herbivore recycling will have larger effects on producer biomass than predator recycling when turnover rates and recycling efficiencies are high and predators prefer local prey. In addition, predictions suggest that consumer-mediated recycling has the largest effects on primary producers when predators prefer allochthonous prey and predator attack rates are high. Finally, our model predicts that consumer-mediated recycling effects may not be largest when external nutrient loading is low. Our model predictions highlight predator and prey feeding relationships, turnover rates, and external nutrient loading rates as key determinants of the strength of cascading trophic interactions. We show that existing hypotheses from specific empirical systems do not occur under all conditions, which further exacerbates the need to consider a broad suite of mechanisms when investigating trophic cascades.

Measurement error, time lag, unmeasured confounding: Considerations for longitudinal estimation of the effect of a mediator in randomised clinical trials.

PubMed

Goldsmith, K A; Chalder, T; White, P D; Sharpe, M; Pickles, A

2018-06-01

Clinical trials are expensive and time-consuming and so should also be used to study how treatments work, allowing for the evaluation of theoretical treatment models and refinement and improvement of treatments. These treatment processes can be studied using mediation analysis. Randomised treatment makes some of the assumptions of mediation models plausible, but the mediator-outcome relationship could remain subject to bias. In addition, mediation is assumed to be a temporally ordered longitudinal process, but estimation in most mediation studies to date has been cross-sectional and unable to explore this assumption. This study used longitudinal structural equation modelling of mediator and outcome measurements from the PACE trial of rehabilitative treatments for chronic fatigue syndrome (ISRCTN 54285094) to address these issues. In particular, autoregressive and simplex models were used to study measurement error in the mediator, different time lags in the mediator-outcome relationship, unmeasured confounding of the mediator and outcome, and the assumption of a constant mediator-outcome relationship over time. Results showed that allowing for measurement error and unmeasured confounding were important. Contemporaneous rather than lagged mediator-outcome effects were more consistent with the data, possibly due to the wide spacing of measurements. Assuming a constant mediator-outcome relationship over time increased precision.

R2 effect-size measures for mediation analysis

PubMed Central

Fairchild, Amanda J.; MacKinnon, David P.; Taborga, Marcia P.; Taylor, Aaron B.

2010-01-01

R2 effect-size measures are presented to assess variance accounted for in mediation models. The measures offer a means to evaluate both component paths and the overall mediated effect in mediation models. Statistical simulation results indicate acceptable bias across varying parameter and sample-size combinations. The measures are applied to a real-world example using data from a team-based health promotion program to improve the nutrition and exercise habits of firefighters. SAS and SPSS computer code are also provided for researchers to compute the measures in their own data. PMID:19363189

R2 effect-size measures for mediation analysis.

PubMed

Fairchild, Amanda J; Mackinnon, David P; Taborga, Marcia P; Taylor, Aaron B

2009-05-01

R(2) effect-size measures are presented to assess variance accounted for in mediation models. The measures offer a means to evaluate both component paths and the overall mediated effect in mediation models. Statistical simulation results indicate acceptable bias across varying parameter and sample-size combinations. The measures are applied to a real-world example using data from a team-based health promotion program to improve the nutrition and exercise habits of firefighters. SAS and SPSS computer code are also provided for researchers to compute the measures in their own data.

The Mediation of Mothers’ Self-Fulfilling Effects on Their Children’s Alcohol Use: Self-Verification, Informational Conformity and Modeling Processes

PubMed Central

Madon, Stephanie; Guyll, Max; Buller, Ashley A.; Scherr, Kyle C.; Willard, Jennifer; Spoth, Richard

2010-01-01

This research examined whether self-fulfilling prophecy effects are mediated by self-verification, informational conformity, and modeling processes. The authors examined these mediational processes across multiple time frames with longitudinal data obtained from two samples of mother – child dyads (N1 = 487; N2 = 287). Children’s alcohol use was the outcome variable. The results provided consistent support for the mediational process of self-verification. In both samples and across several years of adolescence, there was a significant indirect effect of mothers’ beliefs on children’s alcohol use through children’s self-assessed likelihood of drinking alcohol in the future. Comparatively less support was found for informational conformity and modeling processes as mediators of mothers’ self-fulfilling effects. The potential for self-fulfilling prophecies to produce long lasting changes in targets’ behavior via self-verification processes are discussed. PMID:18665708

The mediation of mothers' self-fulfilling effects on their children's alcohol use: self-verification, informational conformity, and modeling processes.

PubMed

Madon, Stephanie; Guyll, Max; Buller, Ashley A; Scherr, Kyle C; Willard, Jennifer; Spoth, Richard

2008-08-01

This research examined whether self-fulfilling prophecy effects are mediated by self-verification, informational conformity, and modeling processes. The authors examined these mediational processes across multiple time frames with longitudinal data obtained from two samples of mother-child dyads (N-sub-1 = 486; N-sub-2 = 287), with children's alcohol use as the outcome variable. The results provided consistent support for the mediational process of self-verification. In both samples and across several years of adolescence, there was a significant indirect effect of mothers' beliefs on children's alcohol use through children's self-assessed likelihood of drinking alcohol in the future. Comparatively less support was found for informational conformity and modeling processes as mediators of mothers' self-fulfilling effects. The potential for self-fulfilling prophecies to produce long-lasting changes in targets' behavior via self-verification processes are discussed. (c) 2008 APA, all rights reserved

Mediator Effect of TPM between TQM and Business Performance in Malaysia Automotive Industry

NASA Astrophysics Data System (ADS)

Ahmad, M. F.; Zakuan, N.; Rasi, Raja Zuraidah R. M.; Hisyamudin, M. N. N.

2015-05-01

Total Quality Management (TQM) is vital management tool in ensuring a company can success in the continuously growing competition in the global market. In order to survive in the global market with intense competition amongst regions and enterprises, the adoption of tools and techniques are essential in improving business performance. However, only few previous studies have examined the mediators and moderators between TQM and business performance. This present research proposed a TQM performance model with mediator effect of TPM with structural equation modelling, which is a more comprehensive model for developing countries, specifically for Malaysia. A questionnaire was prepared and sent to 1500 companies from automotive industry and the related vendors in Malaysia, giving a 21.3 per cent rate. The result concludes that TPM is partial mediation between and TQM and Business Performance with indirect effect (IE) is 0.25 which can be categorised as high mediator effect.

[The mediating role of organizational citizenship behavior between organizational justice and organizational effectiveness in nursing organizations].

PubMed

Park, Wall Yun; Yoon, Sook Hee

2009-04-01

This study was a secondary analysis to verify the mediating role of organizational citizenship behavior (OCB) between organizational justice (OJ) and organizational effectiveness (OE) in nursing organizations. The RN-BSNs and their colleagues in Seoul and Busan were subjects. The data was collected for 20 days between September 13 and October 2, 2004. Two hundred eighty three data sets were used for the final analysis. The fitness of models were tested using AMOS 5. The fitness of hypothetical model was moderate. Procedural Justice (PJ), Interaction Justice (IJ) and Distributive Justice (DJ) had direct effects on Job Satisfaction (JS), Organizational Commitment (OC) and Turnover Intention (TI) in OE, and indirect effects on JS, OC and TI mediated by OCB. The modified model improved with ideal fitness showed the causal relations among OE. In modified model, PJ, IJ and DJ had direct positive effects on OCB and JS and OC in OE, and indirect effects on JS and OC mediated by OCB. JS and OC in OE had a direct negative effect on TI. OCB mediated the relationship between OJ and OE, so the nursing managers should enhance OCB of the nurses in order to improve OE.

The Mediating Role of Loneliness in the Relation Between Social Engagement and Depressive Symptoms Among Older Korean Americans: Do Men and Women Differ?

PubMed Central

2013-01-01

Objectives. This study conceptualized loneliness as a mediator in the relation between social engagement and depressive symptoms and explored gender differences in the mediation model. Various indices of social engagement were considered including living arrangement, social network, and activity participation. Method. Using data from 674 community-dwelling Korean American older adults, we first examined the mediation effect of loneliness in the relation between each of 3 indices of social engagement (not living alone, social network, and activity participation) and depressive symptoms. Subsequently, gender differences in the mediation model were examined. Results. As hypothesized, loneliness was found to mediate the relation between each of the indices of social engagement and depressive symptoms in both men and women. We also observed gender differences in the strength of mediating effects; the effect of living alone was more likely to be mediated by loneliness among men, whereas women showed greater levels of mediation in the models with social network and activity participation. Discussion. Our findings suggest that loneliness may explain the mechanism by which deficits in social engagement exerts its effect on depressive symptoms and that gender differences should be considered in interventions targeting social engagement for mental health promotion. PMID:22929386

Theory of Mind as a mediator variable between neurocognition and functioning in young individuals in treatment with secondary services for non-psychotic disorders.

PubMed

Francesconi, Marta; Minichino, Amedeo; Carrión, Ricardo E; Chiaie, Roberto Delle; Bevilacqua, Arturo; Parisi, Maurizio; Rullo, Santo; Bersani, Francesco Saverio; Biondi, Massimo; Cadenhead, Kristin

2016-12-30

A large body of studies provides evidence for a link between neurocognition, theory of mind (ToM) and functioning in psychotic spectrum disorders (PSDs), with ToM mediating the effect that neurocognition has on functioning. These three constructs and the related mediation effect may characterize different psychiatric syndromes other than PSDs. Structural equation modelling (SEM) was applied to baseline data from a longitudinal study of 138 young individuals with a recent-onset psychiatric disorder. Using SEM, we tested the hypothesis that ToM mediates the effect of neurocognition on functioning independent of the level of psychosis risk and the diagnostic category. In the mediation model the bootstrapping estimate revealed a significant indirect effect that was the association of social cognition with neurocognition and with functional outcome. ToM was significantly associated with neurocognition and the path from neurocognition to functioning was no longer significant as soon as the mediator (ToM) was entered into the mediation model consistent with a complete mediation effect through ToM. This mediation was independent of the psychosis-risk status and the psychiatric diagnoses. Our results provide useful information on a young psychiatric sample, in which specific therapeutic interventions have the potential to significantly limit functional disability. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Smoking mediates the effect of conscientiousness on mortality: The Veterans Affairs Normative Aging Study

PubMed Central

Turiano, Nicholas A.; Hill, Patrick L.; Roberts, Brent W.; Spiro, Avron; Mroczek, Daniel K.

2013-01-01

This study examined the relationship between conscientiousness and mortality over 18 years and whether smoking behavior mediated this relationship. We utilized data from the Veterans Affairs Normative Aging Study on 1349 men who completed the Goldberg (1992) adjectival markers of the Big Five. Over the 18-year follow-up, 547 (41%) participants died. Through proportional hazards modeling in a structural equation modeling framework, we found that higher levels of conscientiousness significantly predicted longer life, and that this effect was mediated by current smoking status at baseline. Methodologically, we also demonstrate the effectiveness of using a structural equation modeling framework to evaluate mediation when using a censored outcome such as mortality. PMID:23504043

Adaptive evolution of body size subject to indirect effect in trophic cascade system.

PubMed

Wang, Xin; Fan, Meng; Hao, Lina

2017-09-01

Trophic cascades represent a classic example of indirect effect and are wide-spread in nature. Their ecological impact are well established, but the evolutionary consequences have received even less theoretical attention. We theoretically and numerically investigate the trait (i.e., body size of consumer) evolution in response to indirect effect in a trophic cascade system. By applying the quantitative trait evolutionary theory and the adaptive dynamic theory, we formulate and explore two different types of eco-evolutionary resource-consumer-predator trophic cascade model. First, an eco-evolutionary model incorporating the rapid evolution is formulated to investigate the effect of rapid evolution of the consumer's body size, and to explore the impact of density-mediate indirect effect on the population dynamics and trait dynamics. Next, by employing the adaptive dynamic theory, a long-term evolutionary model of consumer body size is formulated to evaluate the effect of long-term evolution on the population dynamics and the effect of trait-mediate indirect effect. Those models admit rich dynamics that has not been observed yet in empirical studies. It is found that, both in the trait-mediated and density-mediated system, the body size of consumer in predator-consumer-resource interaction (indirect effect) evolves smaller than that in consumer-resource and predator-consumer interaction (direct effect). Moreover, in the density-mediated system, we found that the evolution of consumer body size contributes to avoiding consumer extinction (i.e., evolutionary rescue). The trait-mediate and density-mediate effects may produce opposite evolutionary response. This study suggests that the trophic cascade indirect effect affects consumer evolution, highlights a more comprehensive mechanistic understanding of the intricate interplay between ecological and evolutionary force. The modeling approaches provide avenue for study on indirect effects from an evolutionary perspective. Copyright © 2017 Elsevier B.V. All rights reserved.

Mediation in dyadic data at the level of the dyads: a Structural Equation Modeling approach.

PubMed

Ledermann, Thomas; Macho, Siegfried

2009-10-01

An extended version of the Common Fate Model (CFM) is presented to estimate and test mediation in dyadic data. The model can be used for distinguishable dyad members (e.g., heterosexual couples) or indistinguishable dyad members (e.g., homosexual couples) if (a) the variables measure characteristics of the dyadic relationship or shared external influences that affect both partners; if (b) the causal associations between the variables should be analyzed at the dyadic level; and if (c) the measured variables are reliable indicators of the latent variables. To assess mediation using Structural Equation Modeling, a general three-step procedure is suggested. The first is a selection of a good fitting model, the second a test of the direct effects, and the third a test of the mediating effect by means of bootstrapping. The application of the model along with the procedure for assessing mediation is illustrated using data from 184 couples on marital problems, communication, and marital quality. Differences with the Actor-Partner Interdependence Model and the analysis of longitudinal mediation by using the CFM are discussed.

Multilevel SEM Strategies for Evaluating Mediation in Three-Level Data

ERIC Educational Resources Information Center

Preacher, Kristopher J.

2011-01-01

Strategies for modeling mediation effects in multilevel data have proliferated over the past decade, keeping pace with the demands of applied research. Approaches for testing mediation hypotheses with 2-level clustered data were first proposed using multilevel modeling (MLM) and subsequently using multilevel structural equation modeling (MSEM) to…

Testing Mediation in Structural Equation Modeling: The Effectiveness of the Test of Joint Significance

ERIC Educational Resources Information Center

Leth-Steensen, Craig; Gallitto, Elena

2016-01-01

A large number of approaches have been proposed for estimating and testing the significance of indirect effects in mediation models. In this study, four sets of Monte Carlo simulations involving full latent variable structural equation models were run in order to contrast the effectiveness of the currently popular bias-corrected bootstrapping…

Mediation Analysis with Survival Outcomes: Accelerated Failure Time vs. Proportional Hazards Models

PubMed Central

Gelfand, Lois A.; MacKinnon, David P.; DeRubeis, Robert J.; Baraldi, Amanda N.

2016-01-01

Objective: Survival time is an important type of outcome variable in treatment research. Currently, limited guidance is available regarding performing mediation analyses with survival outcomes, which generally do not have normally distributed errors, and contain unobserved (censored) events. We present considerations for choosing an approach, using a comparison of semi-parametric proportional hazards (PH) and fully parametric accelerated failure time (AFT) approaches for illustration. Method: We compare PH and AFT models and procedures in their integration into mediation models and review their ability to produce coefficients that estimate causal effects. Using simulation studies modeling Weibull-distributed survival times, we compare statistical properties of mediation analyses incorporating PH and AFT approaches (employing SAS procedures PHREG and LIFEREG, respectively) under varied data conditions, some including censoring. A simulated data set illustrates the findings. Results: AFT models integrate more easily than PH models into mediation models. Furthermore, mediation analyses incorporating LIFEREG produce coefficients that can estimate causal effects, and demonstrate superior statistical properties. Censoring introduces bias in the coefficient estimate representing the treatment effect on outcome—underestimation in LIFEREG, and overestimation in PHREG. With LIFEREG, this bias can be addressed using an alternative estimate obtained from combining other coefficients, whereas this is not possible with PHREG. Conclusions: When Weibull assumptions are not violated, there are compelling advantages to using LIFEREG over PHREG for mediation analyses involving survival-time outcomes. Irrespective of the procedures used, the interpretation of coefficients, effects of censoring on coefficient estimates, and statistical properties should be taken into account when reporting results. PMID:27065906

Social Information Processing Mediates the Intergenerational Transmission of Aggressiveness in Romantic Relationships

PubMed Central

Fite, Jennifer E.; Bates, John E.; Holtzworth-Munroe, Amy; Dodge, Kenneth A.; Nay, Sandra Y.; Pettit, Gregory S.

2012-01-01

This study explored the K. A. Dodge (1986) model of social information processing as a mediator of the association between interparental relationship conflict and subsequent offspring romantic relationship conflict in young adulthood. The authors tested 4 social information processing stages (encoding, hostile attributions, generation of aggressive responses, and positive evaluation of aggressive responses) in separate models to explore their independent effects as potential mediators. There was no evidence of mediation for encoding and attributions. However, there was evidence of significant mediation for both the response generation and response evaluation stages of the model. Results suggest that the ability of offspring to generate varied social responses and effectively evaluate the potential outcome of their responses at least partially mediates the intergenerational transmission of relationship conflict. PMID:18540765

Practical Guidance for Conducting Mediation Analysis With Multiple Mediators Using Inverse Odds Ratio Weighting

PubMed Central

Nguyen, Quynh C.; Osypuk, Theresa L.; Schmidt, Nicole M.; Glymour, M. Maria; Tchetgen Tchetgen, Eric J.

2015-01-01

Despite the recent flourishing of mediation analysis techniques, many modern approaches are difficult to implement or applicable to only a restricted range of regression models. This report provides practical guidance for implementing a new technique utilizing inverse odds ratio weighting (IORW) to estimate natural direct and indirect effects for mediation analyses. IORW takes advantage of the odds ratio's invariance property and condenses information on the odds ratio for the relationship between the exposure (treatment) and multiple mediators, conditional on covariates, by regressing exposure on mediators and covariates. The inverse of the covariate-adjusted exposure-mediator odds ratio association is used to weight the primary analytical regression of the outcome on treatment. The treatment coefficient in such a weighted regression estimates the natural direct effect of treatment on the outcome, and indirect effects are identified by subtracting direct effects from total effects. Weighting renders treatment and mediators independent, thereby deactivating indirect pathways of the mediators. This new mediation technique accommodates multiple discrete or continuous mediators. IORW is easily implemented and is appropriate for any standard regression model, including quantile regression and survival analysis. An empirical example is given using data from the Moving to Opportunity (1994–2002) experiment, testing whether neighborhood context mediated the effects of a housing voucher program on obesity. Relevant Stata code (StataCorp LP, College Station, Texas) is provided. PMID:25693776

Enhanced understanding of the relationship between erection and satisfaction in ED treatment: application of a longitudinal mediation model.

PubMed

Bushmakin, A G; Cappelleri, J C; Symonds, T; Stecher, V J

2014-01-01

To apportion the direct effect and the indirect effect (through erections) that sildenafil (vs placebo) has on individual satisfaction and couple satisfaction over time, longitudinal mediation modeling was applied to outcomes on the Sexual Experience Questionnaire. The model included data from weeks 4 and 10 (double-blind phase) and week 16 (open-label phase) of a controlled study. Data from 167 patients with erectile dysfunction (ED) were available for analysis. Estimation of statistical significance was based on bootstrap simulations, which allowed inferences at and between time points. Percentages (and corresponding 95% confidence intervals) for direct and indirect effects of treatment were calculated using the model. For the individual satisfaction and couple satisfaction domains, direct treatment effects were negligible (not statistically significant) whereas indirect treatment effects via the erection domain represented >90% of the treatment effects (statistically significant). Week 4 vs week 10 percentages of direct and indirect effects were not statistically different, indicating that the mediation effects are longitudinally invariant. As there was no placebo arm in the open-label phase, mediation effects at week 16 were not estimable. In conclusion, erection has a crucial role as a mediator in restoring individual satisfaction and couple satisfaction in men with ED treated with sildenafil.

Mechanisms and mediation in survival analysis: towards an integrated analytical framework.

PubMed

Pratschke, Jonathan; Haase, Trutz; Comber, Harry; Sharp, Linda; de Camargo Cancela, Marianna; Johnson, Howard

2016-02-29

A wide-ranging debate has taken place in recent years on mediation analysis and causal modelling, raising profound theoretical, philosophical and methodological questions. The authors build on the results of these discussions to work towards an integrated approach to the analysis of research questions that situate survival outcomes in relation to complex causal pathways with multiple mediators. The background to this contribution is the increasingly urgent need for policy-relevant research on the nature of inequalities in health and healthcare. The authors begin by summarising debates on causal inference, mediated effects and statistical models, showing that these three strands of research have powerful synergies. They review a range of approaches which seek to extend existing survival models to obtain valid estimates of mediation effects. They then argue for an alternative strategy, which involves integrating survival outcomes within Structural Equation Models via the discrete-time survival model. This approach can provide an integrated framework for studying mediation effects in relation to survival outcomes, an issue of great relevance in applied health research. The authors provide an example of how these techniques can be used to explore whether the social class position of patients has a significant indirect effect on the hazard of death from colon cancer. The results suggest that the indirect effects of social class on survival are substantial and negative (-0.23 overall). In addition to the substantial direct effect of this variable (-0.60), its indirect effects account for more than one quarter of the total effect. The two main pathways for this indirect effect, via emergency admission (-0.12), on the one hand, and hospital caseload, on the other, (-0.10) are of similar size. The discrete-time survival model provides an attractive way of integrating time-to-event data within the field of Structural Equation Modelling. The authors demonstrate the efficacy of this approach in identifying complex causal pathways that mediate the effects of a socio-economic baseline covariate on the hazard of death from colon cancer. The results show that this approach has the potential to shed light on a class of research questions which is of particular relevance in health research.

Working conditions, burnout and stress symptoms in university professors: validating a structural model of the mediating effect of perceived personal competence.

PubMed

Avargues Navarro, María Luisa; Borda Mas, Mercedes; López Jiménez, Ana María

2010-05-01

The purpose of this study has been to test, with a sample of 193 Professors of the University of Seville, a structural model on the mediating role of personal perceived competence in the appearance of burnout syndrome and stress symptoms under potentially stressful work conditions. The instruments used to evaluate were a socio-demographic and work-related data questionnaire, The Maslach Burnout Inventory (M.B.I.), The Labour Scale of Stress and the Magallanes Stress Scale. The model of strategy implementation and LISREL 8.71 were used. The estimated model was adjusted satisfactorily, ascertaining the mediating effect of perceived competence in the effect exerted by the work conditions studied on the depersonalization and personal fulfillment, as well as in the appearance of stress symptoms. The effect on the emotional exhaustion dimension was not confirmed. The latter also acted on the estimated model as a mediating variable, facilitating the negative impact of stressors on emotional exhaustion, depersonalization and personal accomplishment.

Social cognitive mediators of parent-child sexual communication.

PubMed

Evans, W Douglas; Blitstein, Jonathan L; Davis, Kevin C

2011-07-01

To test a social cognitive behavior change model and identify mediators of the effects of the Parents Speak Up National Campaign (PSUNC) on parent-child sexual communication. Investigators used 5 waves of data from an online randomized controlled trial. Latent variables were developed based on item response theory and confirmatory factor analysis. Structural equation modeling was used to test mediation. Outcome expectations mediated effects of social norms and self-efficacy on sexual communication. Other hypothesized mediators were not confirmed. Interventions to promote parent-child sexual communication should target outcome expectations. Future research should investigate parents' health information seeking.

Power Analysis for Complex Mediational Designs Using Monte Carlo Methods

ERIC Educational Resources Information Center

Thoemmes, Felix; MacKinnon, David P.; Reiser, Mark R.

2010-01-01

Applied researchers often include mediation effects in applications of advanced methods such as latent variable models and linear growth curve models. Guidance on how to estimate statistical power to detect mediation for these models has not yet been addressed in the literature. We describe a general framework for power analyses for complex…

Mediation analysis when a continuous mediator is measured with error and the outcome follows a generalized linear model

PubMed Central

Valeri, Linda; Lin, Xihong; VanderWeele, Tyler J.

2014-01-01

Mediation analysis is a popular approach to examine the extent to which the effect of an exposure on an outcome is through an intermediate variable (mediator) and the extent to which the effect is direct. When the mediator is mis-measured the validity of mediation analysis can be severely undermined. In this paper we first study the bias of classical, non-differential measurement error on a continuous mediator in the estimation of direct and indirect causal effects in generalized linear models when the outcome is either continuous or discrete and exposure-mediator interaction may be present. Our theoretical results as well as a numerical study demonstrate that in the presence of non-linearities the bias of naive estimators for direct and indirect effects that ignore measurement error can take unintuitive directions. We then develop methods to correct for measurement error. Three correction approaches using method of moments, regression calibration and SIMEX are compared. We apply the proposed method to the Massachusetts General Hospital lung cancer study to evaluate the effect of genetic variants mediated through smoking on lung cancer risk. PMID:25220625

Structural Equation Model of Smartphone Addiction Based on Adult Attachment Theory: Mediating Effects of Loneliness and Depression.

PubMed

Kim, EunYoung; Cho, Inhyo; Kim, Eun Joo

2017-06-01

This study investigated the mediating effects of loneliness and depression on the relationship between adult attachment and smartphone addiction in university students. A total of 200 university students participated in this study. The data was analysed using descriptive statistics, correlation analysis, and structural equation modeling. There were significant positive relationships between attachment anxiety, loneliness, depression, and smartphone addiction. However, attachment anxiety was not significantly correlated with smartphone addiction. The results also showed that loneliness did not directly mediate between attachment anxiety and smartphone addiction. In addition, loneliness and depression serially mediated between attachment anxiety and smartphone addiction. The results suggest there are mediating effects of loneliness and depression in the relationship between attachment anxiety and smartphone addiction. The hypothesized model was found to be a suitable model for predicting smartphone addiction among university students. Future study is required to find a causal path to prevent smartphone addiction among university students. Copyright © 2017. Published by Elsevier B.V.

An Index and Test of Linear Moderated Mediation.

PubMed

Hayes, Andrew F

2015-01-01

I describe a test of linear moderated mediation in path analysis based on an interval estimate of the parameter of a function linking the indirect effect to values of a moderator-a parameter that I call the index of moderated mediation. This test can be used for models that integrate moderation and mediation in which the relationship between the indirect effect and the moderator is estimated as linear, including many of the models described by Edwards and Lambert ( 2007 ) and Preacher, Rucker, and Hayes ( 2007 ) as well as extensions of these models to processes involving multiple mediators operating in parallel or in serial. Generalization of the method to latent variable models is straightforward. Three empirical examples describe the computation of the index and the test, and its implementation is illustrated using Mplus and the PROCESS macro for SPSS and SAS.

A Mediational Model Explaining the Connection Between Religiosity and Anti-Homosexual Attitudes in Italy: The Effects of Male Role Endorsement and Homosexual Stereotyping.

PubMed

Piumatti, Giovanni

2017-01-01

This study aimed to better understand the relationship between religiosity and anti-homosexual attitudes in Italy by examining the mediation effects of male role endorsement and homosexual stereotyping. A sample of 5,522 Italian residents (age range = 18-74) was drawn from a cross-sectional national representative survey carried out in 2011. Measures included general religiosity, male role endorsement, homosexual stereotyping, social acceptance of homosexuality, and homosexual rights endorsement. Structural equation modeling was used to test the mediational effects of male role endorsement and homosexual stereotyping on the relationship between general religiosity and attitudes toward lesbians and gay men. Results showed that both male role endorsement and homosexual stereotyping partially mediated the relationship. In a model where religiosity and both mediators positively explained anti-homosexual attitudes, male role endorsement was the strongest mediator. Endorsement of gender role beliefs and homosexual stereotyping may thus exacerbate the connection between religiosity and anti-homosexual attitudes among Italians.

Determinants of lifestyle behavior change to prevent type 2 diabetes in high-risk individuals.

PubMed

den Braver, N R; de Vet, E; Duijzer, G; Ter Beek, J; Jansen, S C; Hiddink, G J; Feskens, E J M; Haveman-Nies, A

2017-06-12

Although there are many effective lifestyle interventions for type 2 diabetes (T2DM) prevention, insight into effective intervention pathways, especially of long-term interventions, is often lacking. This study aims to provide insight into the effective intervention pathways of the SLIMMER diabetes prevention intervention using mediation analyses. In total, 240 participants at increased risk of T2DM were included in the analyses over 18 months. The intervention was a combined lifestyle intervention with a dietary and a physical activity (PA) component. The primary and secondary outcomes were change in fasting insulin (pmol/L) and change in body weight (kg) after 18 months, respectively. Firstly, in a multiple mediator model, we investigated whether significant changes in these outcomes were mediated by changes in dietary and PA behavior. Secondly, in multiple single mediator models, we investigated whether changes in dietary and PA behavior were mediated by changes in behavioral determinants and the participants' psychological profile. The mediation analyses used linear regression models, where significance of indirect effects was calculated with bootstrapping. The effect of the intervention on decreased fasting insulin was 40% mediated by change in dietary and PA behavior, where dietary behavior was an independent mediator of the association (34%). The effect of the intervention on decreased body weight was 20% mediated by change in dietary and PA behavior, where PA behavior was an independent mediator (17%). The intervention significantly changed intake of fruit, fat from bread spread, and fiber from bread. Change in fruit intake was mediated by change in action control (combination of consciousness, self-control, and effort), motivation, self-efficacy, intention, and skills. Change in fat intake was mediated by change in action control and psychological profile. No mediators could be identified for change in fiber intake. The change in PA behavior was mediated by change in action control, motivation, and psychological profile. The effect of the SLIMMER intervention on fasting insulin and body weight was mediated by changes in dietary and PA behavior, in distinct ways. These results indicate that changing dietary as well as PA behavior is important in T2DM prevention.

Moderated mediation analysis: An illustration using the association of gender with delinquency and mental health.

PubMed

Miles, Jeremy N V; Kulesza, Magdalena; Ewing, Brett; Shih, Regina A; Tucker, Joan S; D'Amico, Elizabeth J

When researchers find an association between two variables, it is useful to evaluate the role of other constructs in this association. While assessing these mediation effects, it is important to determine if results are equal for different groups. It is possible that the strength of a mediation effect may differ for males and females, for example - such an effect is known as moderated mediation. Participants were 2532 adolescents from diverse ethnic/racial backgrounds and equally distributed across gender. The goal of this study was to investigate parental respect as a potential mediator of the relationship between gender and delinquency and mental health, and to determine whether observed mediation is moderated by gender. Parental respect mediated the association between gender and both delinquency and mental health. Specifically, parental respect was a protective factor against delinquency and mental health problems for both females and males. Demonstrated the process of estimating models in Lavaan, using two approaches (i.e. single group regression and multiple group regression model), and including covariates in both models.

Moderated mediation analysis: An illustration using the association of gender with delinquency and mental health

PubMed Central

Miles, Jeremy N.V.; Kulesza, Magdalena; Ewing, Brett; Shih, Regina A.; Tucker, Joan S.; D’Amico, Elizabeth J.

2015-01-01

Purpose When researchers find an association between two variables, it is useful to evaluate the role of other constructs in this association. While assessing these mediation effects, it is important to determine if results are equal for different groups. It is possible that the strength of a mediation effect may differ for males and females, for example – such an effect is known as moderated mediation. Design Participants were 2532 adolescents from diverse ethnic/racial backgrounds and equally distributed across gender. The goal of this study was to investigate parental respect as a potential mediator of the relationship between gender and delinquency and mental health, and to determine whether observed mediation is moderated by gender. Findings Parental respect mediated the association between gender and both delinquency and mental health. Specifically, parental respect was a protective factor against delinquency and mental health problems for both females and males. Practical implications Demonstrated the process of estimating models in Lavaan, using two approaches (i.e. single group regression and multiple group regression model), and including covariates in both models. PMID:26500722

Effect Size Measures for Mediation Models: Quantitative Strategies for Communicating Indirect Effects

ERIC Educational Resources Information Center

Preacher, Kristopher J.; Kelley, Ken

2011-01-01

The statistical analysis of mediation effects has become an indispensable tool for helping scientists investigate processes thought to be causal. Yet, in spite of many recent advances in the estimation and testing of mediation effects, little attention has been given to methods for communicating effect size and the practical importance of those…

An amodal shared resource model of language-mediated visual attention

PubMed Central

Smith, Alastair C.; Monaghan, Padraic; Huettig, Falk

2013-01-01

Language-mediated visual attention describes the interaction of two fundamental components of the human cognitive system, language and vision. Within this paper we present an amodal shared resource model of language-mediated visual attention that offers a description of the information and processes involved in this complex multimodal behavior and a potential explanation for how this ability is acquired. We demonstrate that the model is not only sufficient to account for the experimental effects of Visual World Paradigm studies but also that these effects are emergent properties of the architecture of the model itself, rather than requiring separate information processing channels or modular processing systems. The model provides an explicit description of the connection between the modality-specific input from language and vision and the distribution of eye gaze in language-mediated visual attention. The paper concludes by discussing future applications for the model, specifically its potential for investigating the factors driving observed individual differences in language-mediated eye gaze. PMID:23966967

Method for evaluating multiple mediators: mediating effects of smoking and COPD on the association between the CHRNA5-A3 variant and lung cancer risk.

PubMed

Wang, Jian; Spitz, Margaret R; Amos, Christopher I; Wu, Xifeng; Wetter, David W; Cinciripini, Paul M; Shete, Sanjay

2012-01-01

A mediation model explores the direct and indirect effects between an independent variable and a dependent variable by including other variables (or mediators). Mediation analysis has recently been used to dissect the direct and indirect effects of genetic variants on complex diseases using case-control studies. However, bias could arise in the estimations of the genetic variant-mediator association because the presence or absence of the mediator in the study samples is not sampled following the principles of case-control study design. In this case, the mediation analysis using data from case-control studies might lead to biased estimates of coefficients and indirect effects. In this article, we investigated a multiple-mediation model involving a three-path mediating effect through two mediators using case-control study data. We propose an approach to correct bias in coefficients and provide accurate estimates of the specific indirect effects. Our approach can also be used when the original case-control study is frequency matched on one of the mediators. We employed bootstrapping to assess the significance of indirect effects. We conducted simulation studies to investigate the performance of the proposed approach, and showed that it provides more accurate estimates of the indirect effects as well as the percent mediated than standard regressions. We then applied this approach to study the mediating effects of both smoking and chronic obstructive pulmonary disease (COPD) on the association between the CHRNA5-A3 gene locus and lung cancer risk using data from a lung cancer case-control study. The results showed that the genetic variant influences lung cancer risk indirectly through all three different pathways. The percent of genetic association mediated was 18.3% through smoking alone, 30.2% through COPD alone, and 20.6% through the path including both smoking and COPD, and the total genetic variant-lung cancer association explained by the two mediators was 69.1%.

The Effect of Religious Involvement on Life Satisfaction among Korean Christians: Focused on the Mediating Effect of Spiritual Well-Being and Self-Esteem.

PubMed

Yoo, Jieun

2017-12-01

The present study examined the relationship between two categories of religious involvement, namely religious belief and religious behavior, and life satisfaction among Korean Christians (N = 278) with spiritual well-being and self-esteem as potential mediators in this relationship by using structural equation modeling (SEM). The results supported the full mediated structural model and indicated that religious belief had a significant indirect effect on life satisfaction through the mediators, spiritual well-being and self-esteem. Religious behavior did not have an indirect or direct effect on life satisfaction among Korean Christians. The significance, implications, and limitations of the study were discussed.

Editorial: Introduction to the Special Section on Causal Inference in Cross Sectional and Longitudinal Mediational Models

PubMed Central

West, Stephen G.

2016-01-01

Psychologists have long had interest in the processes through which antecedent variables produce their effects on the outcomes of ultimate interest (e.g., Wood-worth's Stimulus-Organism-Response model). Models involving such meditational processes have characterized many of the important psychological theories of the 20th century and continue to the present day. However, it was not until Judd and Kenny (1981) and Baron and Kenny (1986) combined ideas from experimental design and structural equation modeling that statistical methods for directly testing such models, now known as mediation analysis, began to be developed. Methodologists have improved these statistical methods, developing new, more efficient estimators for mediated effects. They have also extended mediation analysis to multilevel data structures, models involving multiple mediators, models in which interactions occur, and an array of noncontinuous outcome measures (see MacKinnon, 2008). This work nicely maps on to key questions of applied researchers and has led to an outpouring of research testing meditational models (As of August, 2011, Baron and Kenny's article has had over 24,000 citations according to Google Scholar). PMID:26736046

Accommodating Binary and Count Variables in Mediation: A Case for Conditional Indirect Effects

ERIC Educational Resources Information Center

Geldhof, G. John; Anthony, Katherine P.; Selig, James P.; Mendez-Luck, Carolyn A.

2018-01-01

The existence of several accessible sources has led to a proliferation of mediation models in the applied research literature. Most of these sources assume endogenous variables (e.g., M, and Y) have normally distributed residuals, precluding models of binary and/or count data. Although a growing body of literature has expanded mediation models to…

Adult attachment, perceived social support, cultural orientation, and depressive symptoms: A moderated mediation model.

PubMed

Zhu, Wenzhen; Wang, Chiachih Dc; Chong, Chu Chian

2016-11-01

In the current study, we tested a moderated mediation model in which cultural orientation moderated the mediation model of adult attachment-perceived social support-depressive symptoms, using 2 comparable cross-cultural samples of college students recruited from China and the U.S. (n = 363 for each group). Results indicated that perceived social support mediated the effect of attachment anxiety on depressive symptoms as well as the link between attachment avoidance and depression in both samples. Moderated mediation analyses using PROCESS revealed that interdependent self-construal significantly buffered the indirect effect of attachment avoidance (via perceived social support) on depressive symptoms. The findings indicated significant differences in the mediation models between the U.S. and China groups and interdependent self-construal accounted for the between-country differences. Limitations, implications of the findings, and future research directions are discussed from the perspectives of cross-cultural variation of adult attachment functioning. (PsycINFO Database Record (c) 2016 APA, all rights reserved).

Intrinsic motivation as a mediator of relationships between symptoms and functioning among individuals with schizophrenia spectrum disorders in a diverse urban community.

PubMed

Yamada, Ann-Marie; Lee, Karen K; Dinh, Tam Q; Barrio, Concepción; Brekke, John S

2010-01-01

This study investigated intrinsic motivation as a mediator of the relationship between clinical symptoms and functioning. The mediation model was tested with a sample of 166 adults with schizophrenia spectrum disorders attending psychosocial rehabilitation programs in a diverse urban community. Ethnic minority status was examined as a moderator of the mediation model. Motivation was measured using items reflecting intrapsychic drive. Symptoms were assessed with the expanded Brief Psychiatric Rating Scale and functioning with the Role Functioning Scale. Motivation was a significant mediator of the relationship between functioning and all symptom scores; fully mediating the relationship between functioning and negative, disorganized, and global symptoms, and partially mediating the relationship between positive symptoms and functioning. Motivation scores between ethnic minority and nonminority individuals differed significantly (p < 0.05), but no moderation effect was indicated. The strong mediation effect schizophrenia of motivation on the symptoms-functioning relationship supports future work to translate findings into effective recovery-oriented services.

Intrinsic Motivation as a Mediator of Relationships Between Symptoms and Functioning Among Individuals With Schizophrenia Spectrum Disorders in a Diverse Urban Community

PubMed Central

Yamada, Ann-Marie; Lee, Karen K.; Dinh, Tam Q.; Barrio, Concepción; Brekke, John S.

2010-01-01

This study investigated intrinsic motivation as a mediator of the relationship between clinical symptoms and functioning. The mediation model was tested with a sample of 166 adults with schizophrenia spectrum disorders attending psychosocial rehabilitation programs in a diverse urban community. Ethnic minority status was examined as a moderator of the mediation model. Motivation was measured using items reflecting intrapsychic drive. Symptoms were assessed with the expanded Brief Psychiatric Rating Scale and functioning with the Role Functioning Scale. Motivation was a significant mediator of the relationship between functioning and all symptom scores; fully mediating the relationship between functioning and negative, disorganized, and global symptoms, and partially mediating the relationship between positive symptoms and functioning. Motivation scores between ethnic minority and nonminority individuals differed significantly (p < 0.05), but no moderation effect was indicated. The strong mediation effect schizophrenia of motivation on the symptoms-functioning relationship supports future work to translate findings into effective recovery-oriented services. PMID:20061866

Mediation and moderation: Testing relationships between symptom status, functional health, and quality of life in HIV patients

PubMed Central

Ryu, Ehri; West, Stephen G.; Sousa, Karen H.

2010-01-01

We extended Wilson and Cleary's (1995) health-related quality of life model to examine the relationships among symptoms status (Symptoms), functional health (Disability), and quality of life (QOL). Using a community sample (N = 956) of male HIV positive patients, we tested a mediation model in which the relationship between Symptoms and QOL is partially mediated by Disability. Common and unique ideas from three approaches to examining moderation of effects in mediational models (Edwards & Lambert, 2007; Preacher, Rucker, & Hayes, 2007; MacKinnon, 2008) were used to test whether (a) the direct relationship of Symptoms to QOL and (b) the relationship of Disability to QOL are moderated by age. In the mediation model, both the direct and the indirect (mediated) effects were significant. The direct relationship of Symptoms to QOL was significantly moderated by age, but the relationship of Disability to QOL was not. High Symptoms were associated with lower QOL at all ages, but that this relationship became stronger at older ages. We compare the three approaches and consider their advantages over traditional approaches to combining mediation and moderation. PMID:20706561

[Effect of topical application of a recombinant adenovirus carrying promyelocytic leukemia gene in a psoriasis-like mouse model].

PubMed

Wang, Qiongyu; Zhang, Aijun; Ma, Huiqun; Wang, Shijie; Ma, Yunyun; Zou, Xingwei; Li, Ruilian

2013-03-01

To investigate the effects of topical treatment with adenovirus-mediated promyelocytic leukemia gene (PML) gene in a psoriasis-like mouse model. The effect of adenovirus-mediated PML gene on the granular layer of mouse tail scale epidermis and epithelial mitosis were observed on longitudinal histological sections prepared from the tail skin and vaginal epithelium of the mice. Adenovirus-mediated PML gene significantly inhibited mitosis of mouse vaginal epithelial cells and promoted the formation of granular layer in mouse tail scale epidermis. The therapeutic effect of PML gene in the psoriasis-like mouse model may be associated with increased granular cells and suppressed epidemic cell proliferation.

Parental modeling, education and children's sports and TV time: the ENERGY-project.

PubMed

Fernández-Alvira, Juan M; Te Velde, Saskia J; Singh, Amika; Jiménez-Pavón, David; De Bourdeaudhuij, Ilse; Bere, Elling; Manios, Yannis; Kovacs, Eva; Jan, Nataša; Moreno, Luis A; Brug, Johannes

2015-01-01

We assessed whether differences in children's sports participation and television time according to parental education were mediated by parental modeling. Moreover, we explored the differences between parental and child reports on parental sports participation and television time as potential mediators. 5729 children and 5183 parents participating in the EuropeaN Energy balance Research to prevent excessive weight Gain among Youth (ENERGY-project) during 2010 in seven European countries provided information on sports participation and television time using validated self-report questionnaires. Multilevel country-specific mediation models analyzed the potential mediation effect of parental self-reports and child-reports on parental sports participation and television time. Significant mediation effect was found for parental self-reported television time in four countries (Greece, Hungary, The Netherlands and Slovenia), with the highest proportion for Slovenia (40%) and the lowest for Greece (21%). Child-reported parental television time showed mediation effect in Greece only. Parental self-reported sports participation showed significant mediation effect only in Greece. With child-reported parental sports participation, significant mediation was observed in Greece and Norway. Parental behaviors appear to be important in explaining parental educational differences in children's sports participation and television time. However, child reports on parental behavior appear to be more relevant than parents' self-reports as correlates of children's own sports participation and television time. Copyright © 2014 Elsevier Inc. All rights reserved.

Associations of ethnic discrimination with symptoms of anxiety and depression among Hispanic emerging adults: a moderated mediation model.

PubMed

Cano, Miguel Ángel; Castro, Yessenia; de Dios, Marcel A; Schwartz, Seth J; Lorenzo-Blanco, Elma I; Roncancio, Angelica M; Martinez, Marcos J; Sheehan, Diana M; Auf, Rehab; Piña-Watson, Brandy; Huynh, Que-Lam; Zamboanga, Byron L

2016-11-01

Emerging adulthood is often marked with elevated symptoms of anxiety and depression. Hispanic emerging adults may face cultural stressors such as ethnic discrimination that further increase levels of anxiety and depression symptoms. The study aims were to examine if (a) self-esteem mediated effects of ethnic discrimination on symptoms of anxiety and depression, and (b) if gender moderated the indirect effects of discrimination. The study design was cross-sectional self-report. Two moderated mediation models were tested, with 1084 Hispanic emerging adults (ages 18-25) enrolled in institutions of post-secondary in the United States. Results indicated that (a) higher ethnic discrimination was associated with higher anxiety symptoms (β = .05, p = .04), higher depression symptoms (β = .06, p = .02), and lower self-esteem (β = -.30, p < .001); (b) self-esteem mediated the associations of ethnic discrimination with anxiety and depression symptoms; and (c) gender moderated the indirect effects of discrimination, whereby self-esteem was a stronger mediator among men than women. Each moderated mediation model explained 26% of variability in symptoms of anxiety and depression, respectively. Findings suggest that the mediating effects of self-esteem linking ethnic discrimination with symptoms of anxiety and depression vary between genders.

Generalized causal mediation and path analysis: Extensions and practical considerations.

PubMed

Albert, Jeffrey M; Cho, Jang Ik; Liu, Yiying; Nelson, Suchitra

2018-01-01

Causal mediation analysis seeks to decompose the effect of a treatment or exposure among multiple possible paths and provide casually interpretable path-specific effect estimates. Recent advances have extended causal mediation analysis to situations with a sequence of mediators or multiple contemporaneous mediators. However, available methods still have limitations, and computational and other challenges remain. The present paper provides an extended causal mediation and path analysis methodology. The new method, implemented in the new R package, gmediation (described in a companion paper), accommodates both a sequence (two stages) of mediators and multiple mediators at each stage, and allows for multiple types of outcomes following generalized linear models. The methodology can also handle unsaturated models and clustered data. Addressing other practical issues, we provide new guidelines for the choice of a decomposition, and for the choice of a reference group multiplier for the reduction of Monte Carlo error in mediation formula computations. The new method is applied to data from a cohort study to illuminate the contribution of alternative biological and behavioral paths in the effect of socioeconomic status on dental caries in adolescence.

Comparing models of change to estimate the mediated effect in the pretest-posttest control group design

PubMed Central

Valente, Matthew J.; MacKinnon, David P.

2017-01-01

Models to assess mediation in the pretest-posttest control group design are understudied in the behavioral sciences even though it is the design of choice for evaluating experimental manipulations. The paper provides analytical comparisons of the four most commonly used models used to estimate the mediated effect in this design: Analysis of Covariance (ANCOVA), difference score, residualized change score, and cross-sectional model. Each of these models are fitted using a Latent Change Score specification and a simulation study assessed bias, Type I error, power, and confidence interval coverage of the four models. All but the ANCOVA model make stringent assumptions about the stability and cross-lagged relations of the mediator and outcome that may not be plausible in real-world applications. When these assumptions do not hold, Type I error and statistical power results suggest that only the ANCOVA model has good performance. The four models are applied to an empirical example. PMID:28845097

Comparing models of change to estimate the mediated effect in the pretest-posttest control group design.

PubMed

Valente, Matthew J; MacKinnon, David P

2017-01-01

Models to assess mediation in the pretest-posttest control group design are understudied in the behavioral sciences even though it is the design of choice for evaluating experimental manipulations. The paper provides analytical comparisons of the four most commonly used models used to estimate the mediated effect in this design: Analysis of Covariance (ANCOVA), difference score, residualized change score, and cross-sectional model. Each of these models are fitted using a Latent Change Score specification and a simulation study assessed bias, Type I error, power, and confidence interval coverage of the four models. All but the ANCOVA model make stringent assumptions about the stability and cross-lagged relations of the mediator and outcome that may not be plausible in real-world applications. When these assumptions do not hold, Type I error and statistical power results suggest that only the ANCOVA model has good performance. The four models are applied to an empirical example.

Couple Differentiation: Mediator or Moderator of Depressive Symptoms and Relationship Satisfaction?

PubMed

Bartle-Haring, Suzanne; Ferriby, Megan; Day, Randal

2018-03-09

The purpose of this investigation was to determine whether differentiation at the couple level would act as a moderator or a mediator in the association between marital satisfaction and depressive symptoms over time. In a sample of 412 couples, a latent profile analysis was performed to determine how couple differentiation scores were clustered. An Actor/Partner Interdependence Model was then estimated via a group comparison procedure in structural equation modeling. There was no evidence of a moderating effect of differentiation. A mediating model was then estimated and there was evidence that differentiation mediated the association between depressive symptoms and relationship satisfaction via actor and partner effects. © 2018 American Association for Marriage and Family Therapy.

Alcohol Expectancies as Potential Mediators of Parent Alcoholism Effects on the Development of Adolescent Heavy Drinking.

ERIC Educational Resources Information Center

Colder, Craig R.; Chassin, Laurie; Stice, Eric M.; Curran, Patrick J.

1997-01-01

Used latent growth curve modeling to examine adolescent alcohol expectancies as mediators of effects of parent alcoholism on escalation in adolescent heavy drinking. Found that parent alcoholism directly affected adolescent heavy drinking. Alcohol expectancies did not mediate parent alcoholism effects. Cross-sectional evidence suggested that…

Assessing mediation using marginal structural models in the presence of confounding and moderation

PubMed Central

Coffman, Donna L.; Zhong, Wei

2012-01-01

This paper presents marginal structural models (MSMs) with inverse propensity weighting (IPW) for assessing mediation. Generally, individuals are not randomly assigned to levels of the mediator. Therefore, confounders of the mediator and outcome may exist that limit causal inferences, a goal of mediation analysis. Either regression adjustment or IPW can be used to take confounding into account, but IPW has several advantages. Regression adjustment of even one confounder of the mediator and outcome that has been influenced by treatment results in biased estimates of the direct effect (i.e., the effect of treatment on the outcome that does not go through the mediator). One advantage of IPW is that it can properly adjust for this type of confounding, assuming there are no unmeasured confounders. Further, we illustrate that IPW estimation provides unbiased estimates of all effects when there is a baseline moderator variable that interacts with the treatment, when there is a baseline moderator variable that interacts with the mediator, and when the treatment interacts with the mediator. IPW estimation also provides unbiased estimates of all effects in the presence of non-randomized treatments. In addition, for testing mediation we propose a test of the null hypothesis of no mediation. Finally, we illustrate this approach with an empirical data set in which the mediator is continuous, as is often the case in psychological research. PMID:22905648

Assessing mediation using marginal structural models in the presence of confounding and moderation.

PubMed

Coffman, Donna L; Zhong, Wei

2012-12-01

This article presents marginal structural models with inverse propensity weighting (IPW) for assessing mediation. Generally, individuals are not randomly assigned to levels of the mediator. Therefore, confounders of the mediator and outcome may exist that limit causal inferences, a goal of mediation analysis. Either regression adjustment or IPW can be used to take confounding into account, but IPW has several advantages. Regression adjustment of even one confounder of the mediator and outcome that has been influenced by treatment results in biased estimates of the direct effect (i.e., the effect of treatment on the outcome that does not go through the mediator). One advantage of IPW is that it can properly adjust for this type of confounding, assuming there are no unmeasured confounders. Further, we illustrate that IPW estimation provides unbiased estimates of all effects when there is a baseline moderator variable that interacts with the treatment, when there is a baseline moderator variable that interacts with the mediator, and when the treatment interacts with the mediator. IPW estimation also provides unbiased estimates of all effects in the presence of nonrandomized treatments. In addition, for testing mediation we propose a test of the null hypothesis of no mediation. Finally, we illustrate this approach with an empirical data set in which the mediator is continuous, as is often the case in psychological research. PsycINFO Database Record (c) 2013 APA, all rights reserved.

A General Approach to Causal Mediation Analysis

ERIC Educational Resources Information Center

Imai, Kosuke; Keele, Luke; Tingley, Dustin

2010-01-01

Traditionally in the social sciences, causal mediation analysis has been formulated, understood, and implemented within the framework of linear structural equation models. We argue and demonstrate that this is problematic for 3 reasons: the lack of a general definition of causal mediation effects independent of a particular statistical model, the…

Practical guidance for conducting mediation analysis with multiple mediators using inverse odds ratio weighting.

PubMed

Nguyen, Quynh C; Osypuk, Theresa L; Schmidt, Nicole M; Glymour, M Maria; Tchetgen Tchetgen, Eric J

2015-03-01

Despite the recent flourishing of mediation analysis techniques, many modern approaches are difficult to implement or applicable to only a restricted range of regression models. This report provides practical guidance for implementing a new technique utilizing inverse odds ratio weighting (IORW) to estimate natural direct and indirect effects for mediation analyses. IORW takes advantage of the odds ratio's invariance property and condenses information on the odds ratio for the relationship between the exposure (treatment) and multiple mediators, conditional on covariates, by regressing exposure on mediators and covariates. The inverse of the covariate-adjusted exposure-mediator odds ratio association is used to weight the primary analytical regression of the outcome on treatment. The treatment coefficient in such a weighted regression estimates the natural direct effect of treatment on the outcome, and indirect effects are identified by subtracting direct effects from total effects. Weighting renders treatment and mediators independent, thereby deactivating indirect pathways of the mediators. This new mediation technique accommodates multiple discrete or continuous mediators. IORW is easily implemented and is appropriate for any standard regression model, including quantile regression and survival analysis. An empirical example is given using data from the Moving to Opportunity (1994-2002) experiment, testing whether neighborhood context mediated the effects of a housing voucher program on obesity. Relevant Stata code (StataCorp LP, College Station, Texas) is provided. © The Author 2015. Published by Oxford University Press on behalf of the Johns Hopkins Bloomberg School of Public Health. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Estimation of Indirect Effects in the Presence of Unmeasured Confounding for the Mediator-Outcome Relationship in a Multilevel 2-1-1 Mediation Model

ERIC Educational Resources Information Center

Talloen, Wouter; Moerkerke, Beatrijs; Loeys, Tom; De Naeghel, Jessie; Van Keer, Hilde; Vansteelandt, Stijn

2016-01-01

To assess the direct and indirect effect of an intervention, multilevel 2-1-1 studies with intervention randomized at the upper (class) level and mediator and outcome measured at the lower (student) level are frequently used in educational research. In such studies, the mediation process may flow through the student-level mediator (the within…

Dissociation mediates the relationship between peer victimization and hallucinatory experiences among early adolescents.

PubMed

Yamasaki, Syudo; Ando, Shuntaro; Koike, Shinsuke; Usami, Satoshi; Endo, Kaori; French, Paul; Sasaki, Tsukasa; Furukawa, Toshi A; Hasegawa-Hiraiwa, Mariko; Kasai, Kiyoto; Nishida, Atsushi

2016-06-01

Peer victimization increases the risk of experiencing psychotic symptoms among clinical and general populations, but the mechanism underlying this association remains unclear. Dissociation, which is related to peer victimization and hallucinatory experiences, has been demonstrated as a significant mediator in the relation between childhood victimization and hallucinatory experience among adult patients with psychosis. However, no studies have examined the mediating effect of dissociation in a general early adolescent population. We examined whether dissociation mediates the relationship between peer victimization and hallucinatory experiences among 10-year-old adolescents using a population-based cross-sectional survey of early adolescents and their main parent (Tokyo Early Adolescence Survey; N  = 4478). We examined the mediating effect of dissociation, as well as external locus of control and depressive symptoms, on the relationship between peer victimization and hallucinatory experiences using path analysis. The model assuming mediation effects indicated good model fit (comparative fit index = .999; root mean square error of approximation = .015). The mediation effect between peer victimization and hallucination via dissociation (standardized indirect effect = .038, p  < .001) was statistically significant, whereas the mediation effects of depressive symptoms (standardized indirect effect = -.0066, p  = 0.318) and external locus of control (standardized indirect effect = .0024, p  = 0.321) were not significant. These results suggest that dissociation is a mediator in the relation between peer victimization and hallucinatory experiences in early adolescence. For appropriate intervention strategies, assessing dissociation and peer victimization as they affect hallucinatory experiences is necessary.

Mindfulness facets, trait emotional intelligence, emotional distress, and multiple health behaviors: A serial two-mediator model.

PubMed

Jacobs, Ingo; Wollny, Anna; Sim, Chu-Won; Horsch, Antje

2016-06-01

In the present study, we tested a serial mindfulness facets-trait emotional intelligence (TEI)-emotional distress-multiple health behaviors mediation model in a sample of N = 427 German-speaking occupational therapists. The mindfulness facets-TEI-emotional distress section of the mediation model revealed partial mediation for the mindfulness facets Act with awareness (Act/Aware) and Accept without judgment (Accept); inconsistent mediation was found for the Describe facet. The serial two-mediator model included three mediational pathways that may link each of the four mindfulness facets with multiple health behaviors. Eight out of 12 indirect effects reached significance and fully mediated the links between Act/Aware and Describe to multiple health behaviors; partial mediation was found for Accept. The mindfulness facet Observe was most relevant for multiple health behaviors, but its relation was not amenable to mediation. Implications of the findings will be discussed. © 2016 Scandinavian Psychological Associations and John Wiley & Sons Ltd.

Quantifying and Testing Indirect Effects in Simple Mediation Models when the Constituent Paths Are Nonlinear

ERIC Educational Resources Information Center

Hayes, Andrew F.; Preacher, Kristopher J.

2010-01-01

Most treatments of indirect effects and mediation in the statistical methods literature and the corresponding methods used by behavioral scientists have assumed linear relationships between variables in the causal system. Here we describe and extend a method first introduced by Stolzenberg (1980) for estimating indirect effects in models of…

Social cognition as a mediator variable between neurocognition and functional outcome in schizophrenia: empirical review and new results by structural equation modeling.

PubMed

Schmidt, Stefanie J; Mueller, Daniel R; Roder, Volker

2011-09-01

Cognitive impairments are currently regarded as important determinants of functional domains and are promising treatment goals in schizophrenia. Nevertheless, the exact nature of the interdependent relationship between neurocognition and social cognition as well as the relative contribution of each of these factors to adequate functioning remains unclear. The purpose of this article is to systematically review the findings and methodology of studies that have investigated social cognition as a mediator variable between neurocognitive performance and functional outcome in schizophrenia. Moreover, we carried out a study to evaluate this mediation hypothesis by the means of structural equation modeling in a large sample of 148 schizophrenia patients. The review comprised 15 studies. All but one study provided evidence for the mediating role of social cognition both in cross-sectional and in longitudinal designs. Other variables like motivation and social competence additionally mediated the relationship between social cognition and functional outcome. The mean effect size of the indirect effect was 0.20. However, social cognitive domains were differentially effective mediators. On average, 25% of the variance in functional outcome could be explained in the mediation model. The results of our own statistical analysis are in line with these conclusions: Social cognition mediated a significant indirect relationship between neurocognition and functional outcome. These results suggest that research should focus on differential mediation pathways. Future studies should also consider the interaction with other prognostic factors, additional mediators, and moderators in order to increase the predictive power and to target those factors relevant for optimizing therapy effects.

Methods for integrating moderation and mediation: a general analytical framework using moderated path analysis.

PubMed

Edwards, Jeffrey R; Lambert, Lisa Schurer

2007-03-01

Studies that combine moderation and mediation are prevalent in basic and applied psychology research. Typically, these studies are framed in terms of moderated mediation or mediated moderation, both of which involve similar analytical approaches. Unfortunately, these approaches have important shortcomings that conceal the nature of the moderated and the mediated effects under investigation. This article presents a general analytical framework for combining moderation and mediation that integrates moderated regression analysis and path analysis. This framework clarifies how moderator variables influence the paths that constitute the direct, indirect, and total effects of mediated models. The authors empirically illustrate this framework and give step-by-step instructions for estimation and interpretation. They summarize the advantages of their framework over current approaches, explain how it subsumes moderated mediation and mediated moderation, and describe how it can accommodate additional moderator and mediator variables, curvilinear relationships, and structural equation models with latent variables. (c) 2007 APA, all rights reserved.

Personality and leader effectiveness: a moderated mediation model of leadership self-efficacy, job demands, and job autonomy.

PubMed

Ng, Kok-Yee; Ang, Soon; Chan, Kim-Yin

2008-07-01

The trait theory of leadership is advanced by a joint investigation of the mediating role of (a) leadership self-efficacy (LSE = leader's perceived capabilities to perform leader roles) in linking neuroticism, extraversion, and conscientiousness with leader effectiveness and (b) the moderating role of job demands and job autonomy in influencing the mediation. Using K. J. Preacher, D. D. Rucker, and A. F. Hayes' (2007) moderated mediation framework, the authors tested the model (over a 2-year period) with matched data from 394 military leaders and their supervisors. Results showed that LSE mediated the relationships for neuroticism, extraversion, and conscientiousness with leader effectiveness. Moderated mediation analyses further revealed that LSE mediated the relationships for (a) all 3 personality variables for only those leaders with low job demands; (b) neuroticism and conscientiousness for only those leaders with high job autonomy; and (c) extraversion, regardless of a leader's level of job autonomy. Results underscore the importance of accounting for leaders' situational contexts when examining the relationships between personality, LSE, and effectiveness.

Mediators of the relationship between religiousness/spirituality and alcohol problems in an adult community sample.

PubMed

Drerup, Michelle L; Johnson, Thomas J; Bindl, Stephen

2011-12-01

Johnson et al. (2008b) reported that, in a college student sample, the effect of religiousness on alcohol use was mediated by negative beliefs about alcohol, social influences, and spiritual well-being, and that these variables in turn impacted alcohol use and problems both directly and indirectly via motives for drinking. This study attempted to replicate those findings in a sample of community dwelling adults (N=211). The effect of Religious/Spiritual Involvement was mediated by Negative Beliefs about Alcohol, Social Modeling, and Spiritual-Well-Being. However, Social Modeling had stronger relationships with motives for drinking and alcohol consumption than the other two mediators. The effect of Religious Struggle on Alcohol Problems was mediated by Spiritual Well-Being and coping motives for drinking. Results provide further support for the motivational model of alcohol use and suggest plausible mechanisms by which religiousness could causally impact alcohol use and problems. Religious struggle may be a clinically significant correlate of alcohol problems. Copyright © 2011 Elsevier Ltd. All rights reserved.

The Moderated Mediating Effect of Self-Efficacy on Exercise Among Older Adults in an Online Bone Health Intervention Study: A Parallel Process Latent Growth Curve Model.

PubMed

Zhu, Shijun; Nahm, Eun-Shim; Resnick, Barbara; Friedmann, Erika; Brown, Clayton; Park, Jumin; Cheon, Jooyoung; Park, DoHwan

2017-07-01

This secondary data analyses of a longitudinal study assessed whether self-efficacy for exercise (SEE) mediated online intervention effects on exercise among older adults and whether age (50-64 vs. ≥65 years) moderated the mediation. Data were from an online bone health intervention study. Eight hundred sixty-six older adults (≥50 years) were randomized to three arms: Bone Power (n = 301), Bone Power Plus (n = 302), or Control (n = 263). Parallel process latent growth curve modeling (LGCM) was used to jointly model growths in SEE and in exercise and to assess the mediating effect of SEE on the effect of intervention on exercise. SEE was a significant mediator in 50- to 64-year-old adults (0.061, 95 BCI: 0.011, 0.163) but not in the ≥65 age group (-0.004, 95% BCI: -0.047, 0.025). Promotion of SEE is critical to improve exercise among 50- to 64-year-olds.

Integrating mediation and moderation to advance theory development and testing.

PubMed

Karazsia, Bryan T; Berlin, Kristoffer S; Armstrong, Bridget; Janicke, David M; Darling, Katherine E

2014-03-01

The concepts and associated analyses of mediation and moderation are important to the field of psychology. Although pediatric psychologists frequently incorporate mediation and moderation in their theories and empirical research, on few occasions have we integrated mediation and moderation. In this article, conceptual reasons for integrating mediation and moderation are offered. We illustrate a model that integrates mediation and moderation. In our illustration, the strength of an indirect or a mediating effect varied as a function of a moderating variable. Clinical implications of the integration of mediation and moderation are discussed, as is the potential of integrated models to advance research programs in pediatric psychology.

Testing Mediation Using Multiple Regression and Structural Equation Modeling Analyses in Secondary Data

ERIC Educational Resources Information Center

Li, Spencer D.

2011-01-01

Mediation analysis in child and adolescent development research is possible using large secondary data sets. This article provides an overview of two statistical methods commonly used to test mediated effects in secondary analysis: multiple regression and structural equation modeling (SEM). Two empirical studies are presented to illustrate the…

On the Interpretation and Use of Mediation: Multiple Perspectives on Mediation Analysis.

PubMed

Agler, Robert; De Boeck, Paul

2017-01-01

Mediation analysis has become a very popular approach in psychology, and it is one that is associated with multiple perspectives that are often at odds, often implicitly. Explicitly discussing these perspectives and their motivations, advantages, and disadvantages can help to provide clarity to conversations and research regarding the use and refinement of mediation models. We discuss five such pairs of perspectives on mediation analysis, their associated advantages and disadvantages, and their implications: with vs. without a mediation hypothesis, specific effects vs. a global model, directness vs. indirectness of causation, effect size vs. null hypothesis testing, and hypothesized vs. alternative explanations. Discussion of the perspectives is facilitated by a small simulation study. Some philosophical and linguistic considerations are briefly discussed, as well as some other perspectives we do not develop here.

Measurement error, time lag, unmeasured confounding: Considerations for longitudinal estimation of the effect of a mediator in randomised clinical trials

PubMed Central

Goldsmith, KA; Chalder, T; White, PD; Sharpe, M; Pickles, A

2016-01-01

Clinical trials are expensive and time-consuming and so should also be used to study how treatments work, allowing for the evaluation of theoretical treatment models and refinement and improvement of treatments. These treatment processes can be studied using mediation analysis. Randomised treatment makes some of the assumptions of mediation models plausible, but the mediator–outcome relationship could remain subject to bias. In addition, mediation is assumed to be a temporally ordered longitudinal process, but estimation in most mediation studies to date has been cross-sectional and unable to explore this assumption. This study used longitudinal structural equation modelling of mediator and outcome measurements from the PACE trial of rehabilitative treatments for chronic fatigue syndrome (ISRCTN 54285094) to address these issues. In particular, autoregressive and simplex models were used to study measurement error in the mediator, different time lags in the mediator–outcome relationship, unmeasured confounding of the mediator and outcome, and the assumption of a constant mediator–outcome relationship over time. Results showed that allowing for measurement error and unmeasured confounding were important. Contemporaneous rather than lagged mediator–outcome effects were more consistent with the data, possibly due to the wide spacing of measurements. Assuming a constant mediator–outcome relationship over time increased precision. PMID:27647810

Physician-based activity counseling: intervention effects on mediators of motivational readiness for physical activity.

PubMed

Pinto, B M; Lynn, H; Marcus, B H; DePue, J; Goldstein, M G

2001-01-01

In theory-based interventions for behavior change, there is a need to examine the effects of interventions on the underlying theoretical constructs and the mediating role of such constructs. These two questions are addressed in the Physically Active for Life study, a randomized trial of physician-based exercise counseling for older adults. Three hundred fifty-five patients participated (intervention n = 181, control n = 174; mean age = 65.6 years). The underlying theories used were the Transtheoretical Model, Social Cognitive Theory and the constructs of decisional balance (benefits and barriers), self-efficacy, and behavioral and cognitive processes of change. Motivational readiness for physical activity and related constructs were assessed at baseline, 6 weeks, and 8 months. Linear or logistic mixed effects models were used to examine intervention effects on the constructs, and logistic mixed effects models were used for mediator analyses. At 6 weeks, the intervention had significant effects on decisional balance, self-efficacy, and behavioral processes, but these effects were not maintained at 8 months. At 6 weeks, only decisional balance and behavioral processes were identified as mediators of motivational readiness outcomes. Results suggest that interventions of greater intensity and duration may be needed for sustained changes in mediators and motivational readiness for physical activity among older adults.

Nonlinear Predictive Models for Multiple Mediation Analysis: With an Application to Explore Ethnic Disparities in Anxiety and Depression Among Cancer Survivors.

PubMed

Yu, Qingzhao; Medeiros, Kaelen L; Wu, Xiaocheng; Jensen, Roxanne E

2018-04-02

Mediation analysis allows the examination of effects of a third variable (mediator/confounder) in the causal pathway between an exposure and an outcome. The general multiple mediation analysis method (MMA), proposed by Yu et al., improves traditional methods (e.g., estimation of natural and controlled direct effects) to enable consideration of multiple mediators/confounders simultaneously and the use of linear and nonlinear predictive models for estimating mediation/confounding effects. Previous studies find that compared with non-Hispanic cancer survivors, Hispanic survivors are more likely to endure anxiety and depression after cancer diagnoses. In this paper, we applied MMA on MY-Health study to identify mediators/confounders and quantify the indirect effect of each identified mediator/confounder in explaining ethnic disparities in anxiety and depression among cancer survivors who enrolled in the study. We considered a number of socio-demographic variables, tumor characteristics, and treatment factors as potential mediators/confounders and found that most of the ethnic differences in anxiety or depression between Hispanic and non-Hispanic white cancer survivors were explained by younger diagnosis age, lower education level, lower proportions of employment, less likely of being born in the USA, less insurance, and less social support among Hispanic patients.

Tests of Mediation: Paradoxical Decline in Statistical Power as a Function of Mediator Collinearity

ERIC Educational Resources Information Center

Beasley, T. Mark

2014-01-01

Increasing the correlation between the independent variable and the mediator ("a" coefficient) increases the effect size ("ab") for mediation analysis; however, increasing a by definition increases collinearity in mediation models. As a result, the standard error of product tests increase. The variance inflation caused by…

The Mediating Role of Perceived Descriptive and Injunctive Norms in the Effects of Media Messages on Youth Smoking.

PubMed

Nan, Xiaoli; Zhao, Xiaoquan

2016-01-01

This research advances and tests a normative mediation model of media effects on youth smoking. The model predicts that exposure to various types of smoking-related media messages, including anti-smoking ads, cigarette ads, and smoking scenes in movies and television shows, exerts indirect effects on youth smoking intentions through the mediation of perceived descriptive and injunctive norms. Analysis of the data from the 3rd Legacy Media Tracking Survey offers general support for the proposed model with some unexpected findings, revealing a complex picture of media influence on youth smoking via normative and non-normative mechanisms. Theoretical and practical implications of the findings are discussed.

Passion, Trait Self-Control, and Wellbeing: Comparing Two Mediation Models Predicting Wellbeing.

PubMed

Briki, Walid

2017-01-01

Research has found that passion and trait self-control represented key determinants of wellbeing. Yet, no study to date has attempted to investigate the mediating influences of trait self-control and passion for accounting for the relationships between passion, trait self-control, and wellbeing (dependent variable). Using different frameworks, such as the dualistic model of passion and the neo-socioanalytic theory, the present study proposed two mediation models, considering either trait self-control (model 1) or passion (model 2) as the mediating variable. Five hundred nine volunteers from the United States (326 females and 183 males; M age = 31.74, SD age = 11.05, from 18 to 70 years old), who reported being passionate about a specific activity (e.g., fishing, swimming, blogging; M passion = 5.94, SD passion = 0.89), answered questionnaires assessing harmonious and obsessive passion, trait self-control, and wellbeing (measured through hedonic and eudaimonic wellbeing scales). Preliminary analyses revealed that both models were significant ( model 1: absolute GoF = 0.366, relative GoF = 0.971, outer model GoF = 0.997, inner model GoF = 0.973, R 2 = 18.300%, p < 0.001; model 2: absolute GoF = 0.298; relative GoF = 0.980; outer model GoF = 0.997; inner model GoF = 0.982; R 2 = 12.111%, p < 0.001). Correlational analyses revealed positive relationships between harmonious passion, trait self-control, and wellbeing, and no relationships of obsessive passion with trait self-control and wellbeing. Mediation analyses revealed that trait self-control significantly mediated the relationship between harmonious passion and wellbeing (i.e., partial mediation, VAF = 33.136%). Harmonious passion appeared to significantly mediate the positive effect of trait self-control on wellbeing; however, the size of the mediating effect indicated that (almost) no mediation would take place (i.e., VAF = 11.144%). The present study is the first to examine the relationships between passion, trait self-control, and wellbeing, and supports the view that trait self-control and harmonious passion represent not only adaptive and powerful constructs, but also key determinants of wellbeing. Implications for the study of passion, trait self-control and wellbeing are discussed.

Passion, Trait Self-Control, and Wellbeing: Comparing Two Mediation Models Predicting Wellbeing

PubMed Central

Briki, Walid

2017-01-01

Research has found that passion and trait self-control represented key determinants of wellbeing. Yet, no study to date has attempted to investigate the mediating influences of trait self-control and passion for accounting for the relationships between passion, trait self-control, and wellbeing (dependent variable). Using different frameworks, such as the dualistic model of passion and the neo-socioanalytic theory, the present study proposed two mediation models, considering either trait self-control (model 1) or passion (model 2) as the mediating variable. Five hundred nine volunteers from the United States (326 females and 183 males; Mage = 31.74, SDage = 11.05, from 18 to 70 years old), who reported being passionate about a specific activity (e.g., fishing, swimming, blogging; Mpassion = 5.94, SDpassion = 0.89), answered questionnaires assessing harmonious and obsessive passion, trait self-control, and wellbeing (measured through hedonic and eudaimonic wellbeing scales). Preliminary analyses revealed that both models were significant (model 1: absolute GoF = 0.366, relative GoF = 0.971, outer model GoF = 0.997, inner model GoF = 0.973, R2 = 18.300%, p < 0.001; model 2: absolute GoF = 0.298; relative GoF = 0.980; outer model GoF = 0.997; inner model GoF = 0.982; R2 = 12.111%, p < 0.001). Correlational analyses revealed positive relationships between harmonious passion, trait self-control, and wellbeing, and no relationships of obsessive passion with trait self-control and wellbeing. Mediation analyses revealed that trait self-control significantly mediated the relationship between harmonious passion and wellbeing (i.e., partial mediation, VAF = 33.136%). Harmonious passion appeared to significantly mediate the positive effect of trait self-control on wellbeing; however, the size of the mediating effect indicated that (almost) no mediation would take place (i.e., VAF = 11.144%). The present study is the first to examine the relationships between passion, trait self-control, and wellbeing, and supports the view that trait self-control and harmonious passion represent not only adaptive and powerful constructs, but also key determinants of wellbeing. Implications for the study of passion, trait self-control and wellbeing are discussed. PMID:28611704

Flexible Mediation Analysis With Multiple Mediators.

PubMed

Steen, Johan; Loeys, Tom; Moerkerke, Beatrijs; Vansteelandt, Stijn

2017-07-15

The advent of counterfactual-based mediation analysis has triggered enormous progress on how, and under what assumptions, one may disentangle path-specific effects upon combining arbitrary (possibly nonlinear) models for mediator and outcome. However, current developments have largely focused on single mediators because required identification assumptions prohibit simple extensions to settings with multiple mediators that may depend on one another. In this article, we propose a procedure for obtaining fine-grained decompositions that may still be recovered from observed data in such complex settings. We first show that existing analytical approaches target specific instances of a more general set of decompositions and may therefore fail to provide a comprehensive assessment of the processes that underpin cause-effect relationships between exposure and outcome. We then outline conditions for obtaining the remaining set of decompositions. Because the number of targeted decompositions increases rapidly with the number of mediators, we introduce natural effects models along with estimation methods that allow for flexible and parsimonious modeling. Our procedure can easily be implemented using off-the-shelf software and is illustrated using a reanalysis of the World Health Organization's Large Analysis and Review of European Housing and Health Status (WHO-LARES) study on the effect of mold exposure on mental health (2002-2003). © The Author(s) 2017. Published by Oxford University Press on behalf of the Johns Hopkins Bloomberg School of Public Health. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

The Relationship Between Resilience and Internet Addiction: A Multiple Mediation Model Through Peer Relationship and Depression.

PubMed

Zhou, Pingyan; Zhang, Cai; Liu, Jian; Wang, Zhe

2017-10-01

Heavy use of the Internet may lead to profound academic problems in elementary students, such as poor grades, academic probation, and even expulsion from school. It is of great concern that Internet addiction problems in elementary school students have increased sharply in recent years. In this study, 58,756 elementary school students from the Henan province of China completed four questionnaires to explore the mechanisms of Internet addiction. The results showed that resilience was negatively correlated with Internet addiction. There were three mediational paths in the model: (a) the mediational path through peer relationship with an effect size of 50.0 percent, (b) the mediational path through depression with an effect size of 15.6 percent, (c) the mediational path through peer relationship and depression with an effect size of 13.7 percent. The total mediational effect size was 79.27 percent. The effect size through peer relationship was the strongest among the three mediation paths. The current findings suggest that resilience is a predictor of Internet addiction. Improving children's resilience (such as toughness, emotional control, and problem solving) can be an effective way to reduce Internet addiction behavior. The current findings provide useful information for early detection and intervention for Internet addiction.

Organizational Climate Partially Mediates the Effect of Culture on Work Attitudes and Staff Turnover in Mental Health Services

PubMed Central

Aarons, Gregory A.; Sawitzky, Angelina C.

2006-01-01

Staff turnover in mental health service organizations is an ongoing problem with implications for staff morale, productivity, organizational effectiveness, and implementation of innovation. Recent studies in public sector services have examined the impact of organizational culture and climate on work attitudes (i.e., job satisfaction and organizational commitment) and, ultimately, staff turnover. However, mediational models of the impact of culture and climate on work attitudes have not been examined. The present study examined full and partial mediation models of the effects of culture and climate on work attitudes and the subsequent impact of work attitudes on staff turnover. Multilevel structural equation models supported a partial mediation model in which organizational culture had both direct influence on work attitudes and indirect influence through organizational climate. Work attitudes significantly predicted one-year staff turnover rates. These findings support the contention that both culture and climate impact work attitudes and subsequent staff turnover. PMID:16544205

Organizational climate partially mediates the effect of culture on work attitudes and staff turnover in mental health services.

PubMed

Aarons, Gregory A; Sawitzky, Angelina C

2006-05-01

Staff turnover in mental health service organizations is an ongoing problem with implications for staff morale, productivity, organizational effectiveness, and implementation of innovation. Recent studies in public sector services have examined the impact of organizational culture and climate on work attitudes (i.e., job satisfaction and organizational commitment) and, ultimately, staff turnover. However, mediational models of the impact of culture and climate on work attitudes have not been examined. The present study examined full and partial mediation models of the effects of culture and climate on work attitudes and the subsequent impact of work attitudes on staff turnover. Multilevel structural equation models supported a partial mediation model in which organizational culture had both direct influence on work attitudes and indirect influence through organizational climate. Work attitudes significantly predicted one-year staff turnover rates. These findings support the contention that both culture and climate impact work attitudes and subsequent staff turnover.

Best (but oft-forgotten) practices: mediation analysis.

PubMed

Fairchild, Amanda J; McDaniel, Heather L

2017-06-01

This contribution in the "Best (but Oft-Forgotten) Practices" series considers mediation analysis. A mediator (sometimes referred to as an intermediate variable, surrogate endpoint, or intermediate endpoint) is a third variable that explains how or why ≥2 other variables relate in a putative causal pathway. The current article discusses mediation analysis with the ultimate intention of helping nutrition researchers to clarify the rationale for examining mediation, avoid common pitfalls when using the model, and conduct well-informed analyses that can contribute to improving causal inference in evaluations of underlying mechanisms of effects on nutrition-related behavioral and health outcomes. We give specific attention to underevaluated limitations inherent in common approaches to mediation. In addition, we discuss how to conduct a power analysis for mediation models and offer an applied example to demonstrate mediation analysis. Finally, we provide an example write-up of mediation analysis results as a model for applied researchers. © 2017 American Society for Nutrition.

Best (but oft-forgotten) practices: mediation analysis12

PubMed Central

McDaniel, Heather L

2017-01-01

This contribution in the “Best (but Oft-Forgotten) Practices” series considers mediation analysis. A mediator (sometimes referred to as an intermediate variable, surrogate endpoint, or intermediate endpoint) is a third variable that explains how or why ≥2 other variables relate in a putative causal pathway. The current article discusses mediation analysis with the ultimate intention of helping nutrition researchers to clarify the rationale for examining mediation, avoid common pitfalls when using the model, and conduct well-informed analyses that can contribute to improving causal inference in evaluations of underlying mechanisms of effects on nutrition-related behavioral and health outcomes. We give specific attention to underevaluated limitations inherent in common approaches to mediation. In addition, we discuss how to conduct a power analysis for mediation models and offer an applied example to demonstrate mediation analysis. Finally, we provide an example write-up of mediation analysis results as a model for applied researchers. PMID:28446497

Learning Organization and Innovative Behavior: The Mediating Effect of Work Engagement

ERIC Educational Resources Information Center

Park, Yu Kyoung; Song, Ji Hoon; Yoon, Seung Won; Kim, Jungwoo

2014-01-01

Purpose: The purpose of this study is to investigate the mediating effect of work engagement on the relationship between learning organization and innovative behavior. Design/methodology/approach: This study used surveys as a data collection tool and implemented structural equation modeling for empirically testing the proposed research model.…

Building a Narrative Based Requirements Engineering Mediation Model

NASA Astrophysics Data System (ADS)

Ma, Nan; Hall, Tracy; Barker, Trevor

This paper presents a narrative-based Requirements Engineering (RE) mediation model to help RE practitioners to effectively identify, define, and resolve conflicts of interest, goals, and requirements. Within the SPI community, there is a common belief that social, human, and organizational issues significantly impact on the effectiveness of software process improvement in general and the requirements engineering process in particularl. Conflicts among different stakeholders are an important human and social issue that need more research attention in the SPI and RE community. By drawing on the conflict resolution literature and IS literature, we argue that conflict resolution in RE is a mediated process, in which a requirements engineer can act as a mediator among different stakeholders. To address socio-psychological aspects of conflict in RE and SPI, Winslade and Monk (2000)'s narrative mediation model is introduced, justified, and translated into the context of RE.

Effects of Social Determinants on Chinese Immigrant Food Service Workers' Work Performance and Injuries: Mental Health as a Mediator.

PubMed

Tsai, Jenny Hsin-Chun; Thompson, Elaine Adams

2015-07-01

The effects of social discrimination, job concerns, and social support on worker mental health and the influence of mental health on occupational health outcomes have been documented intermittently. We propose an integrated, theory-driven model to distinguish the impact of social determinants on work performance and injuries and the mediating effects of mental health problems. The US Chinese immigrant food service workers (N = 194) completed a multimeasure interview; we tested the integrated model using structural equation modeling. Mental health problems, which were associated with decreased work performance and increased injuries, also mediated relationships between job/employment concerns and both work performance and injuries but did not mediate the influences of discrimination and social support. This research reveals mechanisms by which social determinants influence immigrant worker health, pointing to complementary strategies for reducing occupational health disparities.

A test of the stress-buffering model of social support in smoking cessation: is the relationship between social support and time to relapse mediated by reduced withdrawal symptoms?

PubMed

Creswell, Kasey G; Cheng, Yu; Levine, Michele D

2015-05-01

Social support has been linked to quitting smoking, but the mechanisms by which social support affects cessation are poorly understood. The current study tested a stress-buffering model of social support, which posits that social support protects or "buffers" individuals from stress related to quitting smoking. We hypothesized that social support would be negatively associated with risk of relapse, and that this effect would be mediated by reduced withdrawal and depressive symptoms (i.e., cessation-related stress) over time. Further, we predicted that trait neuroticism would moderate this mediational effect, such that individuals high in negative affectivity would show the greatest stress-buffering effects of social support. Participants were weight-concerned women (n = 349) ages 18-65 enrolled in a randomized, double-blind, placebo-controlled smoking cessation trial of bupropion and cognitive behavioral therapy. Social support was assessed at baseline, and biochemically-verified abstinence, withdrawal-related symptoms, and depressive symptoms were assessed at 1-, 3-, 6-, and 12-months follow-up. Social support was negatively related to risk of relapse in survival models and negatively related to withdrawal symptoms and depression in mixed effects models. These relationships held after controlling for the effects of pre-quit day negative affect and depression symptoms, assignment to treatment condition, and number of cigarettes smoked per day. A temporal mediation model showed that the effect of social support on risk of relapse was mediated by reductions in withdrawal symptoms over time but not by depression over time. Contrary to hypotheses, we did not find that neuroticism moderated this mediation effect. Increased social support may buffer women from the harmful effects of cessation-related withdrawal symptoms, which in turn improve cessation outcomes. © The Author 2014. Published by Oxford University Press on behalf of the Society for Research on Nicotine and Tobacco. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

A Test of the Stress-Buffering Model of Social Support in Smoking Cessation: Is the Relationship Between Social Support and Time to Relapse Mediated by Reduced Withdrawal Symptoms?

PubMed Central

Cheng, Yu; Levine, Michele D.

2015-01-01

Introduction: Social support has been linked to quitting smoking, but the mechanisms by which social support affects cessation are poorly understood. The current study tested a stress-buffering model of social support, which posits that social support protects or “buffers” individuals from stress related to quitting smoking. We hypothesized that social support would be negatively associated with risk of relapse, and that this effect would be mediated by reduced withdrawal and depressive symptoms (i.e., cessation-related stress) over time. Further, we predicted that trait neuroticism would moderate this mediational effect, such that individuals high in negative affectivity would show the greatest stress-buffering effects of social support. Methods: Participants were weight-concerned women (n = 349) ages 18–65 enrolled in a randomized, double-blind, placebo-controlled smoking cessation trial of bupropion and cognitive behavioral therapy. Social support was assessed at baseline, and biochemically-verified abstinence, withdrawal-related symptoms, and depressive symptoms were assessed at 1-, 3-, 6-, and 12-months follow-up. Results: Social support was negatively related to risk of relapse in survival models and negatively related to withdrawal symptoms and depression in mixed effects models. These relationships held after controlling for the effects of pre-quit day negative affect and depression symptoms, assignment to treatment condition, and number of cigarettes smoked per day. A temporal mediation model showed that the effect of social support on risk of relapse was mediated by reductions in withdrawal symptoms over time but not by depression over time. Contrary to hypotheses, we did not find that neuroticism moderated this mediation effect. Conclusions: Increased social support may buffer women from the harmful effects of cessation-related withdrawal symptoms, which in turn improve cessation outcomes. PMID:25257978

Cognitive and affective mechanisms of pain and fatigue in multiple sclerosis.

PubMed

Arewasikporn, Anne; Turner, Aaron P; Alschuler, Kevin N; Hughes, Abbey J; Ehde, Dawn M

2018-06-01

To examine the extent to which pain catastrophizing, fatigue catastrophizing, positive affect, and negative affect simultaneously mediated the associations between common symptoms of multiple sclerosis (MS; i.e., pain, fatigue) and impact on daily life, depressive symptoms, and resilience. Participants were community-dwelling adults with MS (N = 163) reporting chronic pain, fatigue, and/or moderate depressive symptoms. Multiple mediation path analysis was used to model potential mediators of pain and fatigue separately, using baseline data from a randomized controlled trial comparing two symptom self-management interventions. In the pain model, pain catastrophizing was a mediator of pain intensity with pain interference and depression. Negative affect was a mediator of pain intensity with depression and resilience. In the fatigue model, fatigue catastrophizing was a mediator of fatigue intensity with fatigue impact and depression. Positive affect was a mediator of fatigue intensity with depression and resilience. These findings provide preliminary support for the presence of differential effects of cognitive-affective mediators and suggest potential targets for psychological interventions based on an individual's clinical presentation. The differential mediating effects also support the inclusion of both positive and negative aspects of psychological health in models of pain and fatigue, which would not be otherwise apparent if negative constructs were examined in isolation. To our knowledge, this is the first study to utilize a multivariate path analysis approach to examine cognitive-affective mediators of pain and fatigue in MS, while also examining positive and negative constructs concurrently. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

Supervisor-Subordinate Relationship, Differentiation, and Employee Creativity: A Self-Categorization Perspective

ERIC Educational Resources Information Center

Zhao, Hongdan; Kessel, Maura; Kratzer, Jan

2014-01-01

This study seeks to explore the effect of the quality of supervisor-subordinate relationship (i.e., leader-member exchange; LMX) on employee creativity by examining a moderated-mediation model. The model focuses on the mediating role of perceived insider status and the moderating role of perceived LMX differentiation in influencing the mediation.…

Lotka-Volterra pairwise modeling fails to capture diverse pairwise microbial interactions

PubMed Central

Momeni, Babak; Xie, Li; Shou, Wenying

2017-01-01

Pairwise models are commonly used to describe many-species communities. In these models, an individual receives additive fitness effects from pairwise interactions with each species in the community ('additivity assumption'). All pairwise interactions are typically represented by a single equation where parameters reflect signs and strengths of fitness effects ('universality assumption'). Here, we show that a single equation fails to qualitatively capture diverse pairwise microbial interactions. We build mechanistic reference models for two microbial species engaging in commonly-found chemical-mediated interactions, and attempt to derive pairwise models. Different equations are appropriate depending on whether a mediator is consumable or reusable, whether an interaction is mediated by one or more mediators, and sometimes even on quantitative details of the community (e.g. relative fitness of the two species, initial conditions). Our results, combined with potential violation of the additivity assumption in many-species communities, suggest that pairwise modeling will often fail to predict microbial dynamics. DOI: http://dx.doi.org/10.7554/eLife.25051.001 PMID:28350295

Role of Self-Directed Learning in Communication Competence and Self-Efficacy.

PubMed

Song, Youngshin; Yun, Soon Young; Kim, Sun-Ae; Ahn, Eun-Kyong; Jung, Mi Sook

2015-10-01

Although effective self-directed learning (SDL) has been shown to improve clinical performance, little is known about its role between communication competence and communication self-efficacy in nursing students. This study aimed to identify whether SDL mediates the relationship between communication competence and communication self-efficacy. A cross-sectional survey was conducted with a sample of 213 nursing students taking a basic fundamentals of nursing course. A path diagram, using structural equation modeling, was used to estimate the direct and indirect effects of communication competence on communication self-efficacy, controlling for SDL as a mediator. A structural equation model confirmed direct and indirect effects of communication competence on communication self-efficacy when SDL was controlled as a mediator. An appropriate fit to the data was identified in this mediation model of SDL. For enhancing self-efficacy regarding communication skill, the specified SDL program based on the level of communication competence will yield more effective results. Copyright 2015, SLACK Incorporated.

Mediators of the Association of Major Depressive Syndrome and Anxiety Syndrome with Postpartum Smoking Relapse

PubMed Central

Correa-Fernández, Virmarie; Ji, Lingyun; Castro, Yessenia; Heppner, Whitney L.; Vidrine, Jennifer Irvin; Costello, Tracy J.; Mullen, Patricia Dolan; Cofta-Woerpel, Ludmila; Velasquez, Mary M.; Greisinger, Anthony; Cinciripini, Paul M.; Wetter, David W.

2012-01-01

Objective Based on conceptual models of addiction and affect regulation, this study examined the mechanisms linking current major depressive syndrome (MDS) and anxiety syndrome (AS) to postpartum smoking relapse. Method Data were collected in a randomized clinical trial from 251 women who quit smoking during pregnancy. Simple and multiple mediation models of the relations of MDS and AS with postpartum relapse were examined using linear regression, continuation ratio logit models, and a Bootstrapping procedure to test the indirect effects. Results Both MDS and AS significantly predicted postpartum smoking relapse. After adjusting for MDS, AS significantly predicted relapse. However, after adjusting for AS, MDS no longer predicted relapse. Situationally-based self-efficacy, expectancies of controlling negative affect by means other than smoking, and various dimensions of primary and secondary tobacco dependence individually mediated the effect of both MDS and AS on relapse. In multiple mediation models, self-efficacy in negative/affective situations significantly mediated the effect of MDS and AS on relapse. Conclusion The findings underscore the negative impact of depression and anxiety on postpartum smoking relapse, and suggest that the effects of MDS on postpartum relapse may be largely explained by comorbid AS. The current investigation provided mixed support for affect regulation models of addiction. Cognitive and tobacco dependence-related aspects of negative and positive reinforcement significantly mediated the relationship of depression and anxiety with relapse, while affect and stress did not. The findings emphasize the unique role of low agency with respect to abstaining from smoking in negative affective situations as a key predictor of postpartum smoking relapse. PMID:22390410

Mediators of the association of major depressive syndrome and anxiety syndrome with postpartum smoking relapse.

PubMed

Correa-Fernández, Virmarie; Ji, Lingyun; Castro, Yessenia; Heppner, Whitney L; Vidrine, Jennifer Irvin; Costello, Tracy J; Mullen, Patricia Dolan; Cofta-Woerpel, Ludmila; Velasquez, Mary M; Greisinger, Anthony; Cinciripini, Paul M; Wetter, David W

2012-08-01

Based on conceptual models of addiction and affect regulation, this study examined the mechanisms linking current major depressive syndrome (MDS) and anxiety syndrome (AS) to postpartum smoking relapse. Data were collected in a randomized clinical trial from 251 women who quit smoking during pregnancy. Simple and multiple mediation models of the relations of MDS and AS with postpartum relapse were examined using linear regression, continuation ratio logit models, and a bootstrapping procedure to test the indirect effects. Both MDS and AS significantly predicted postpartum smoking relapse. After adjusting for MDS, AS significantly predicted relapse. However, after adjusting for AS, MDS no longer predicted relapse. Situationally based self-efficacy, expectancies of controlling negative affect by means other than smoking, and various dimensions of primary and secondary tobacco dependence individually mediated the effect of both MDS and AS on relapse. In multiple mediation models, self-efficacy in negative/affective situations significantly mediated the effect of MDS and AS on relapse. The findings underscore the negative impact of depression and anxiety on postpartum smoking relapse and suggest that the effects of MDS on postpartum relapse may be largely explained by comorbid AS. The current investigation provided mixed support for affect regulation models of addiction. Cognitive and tobacco dependence-related aspects of negative and positive reinforcement significantly mediated the relationship of depression and anxiety with relapse, whereas affect and stress did not. The findings emphasize the unique role of low agency with respect to abstaining from smoking in negative affective situations as a key predictor of postpartum smoking relapse. © 2012 American Psychological Association

Within-Subject Mediation Analysis in AB/BA Crossover Designs.

PubMed

Josephy, Haeike; Vansteelandt, Stijn; Vanderhasselt, Marie-Anne; Loeys, Tom

2015-05-01

Crossover trials are widely used to assess the effect of a reversible exposure on an outcome of interest. To gain further insight into the underlying mechanisms of this effect, researchers may be interested in exploring whether or not it runs through a specific intermediate variable: the mediator. Mediation analysis in crossover designs has received scant attention so far and is mostly confined to the traditional Baron and Kenny approach. We aim to tackle mediation analysis within the counterfactual framework and elucidate the assumptions under which the direct and indirect effects can be identified in AB/BA crossover studies. Notably, we show that both effects are identifiable in certain statistical models, even in the presence of unmeasured time-independent (or upper-level) confounding of the mediator-outcome relation. Employing the mediation formula, we derive expressions for the direct and indirect effects in within-subject designs for continuous outcomes that lend themselves to linear modelling, under a large variety of settings. We discuss an estimation approach based on regressing differences in outcomes on differences in mediators and show how to allow for period effects as well as different types of moderation. The performance of this approach is compared to other existing methods through simulations and is illustrated with data from a neurobehavioural study. Lastly, we demonstrate how a sensitivity analysis can be performed that is able to assess the robustness of both the direct and indirect effect against violation of the "no unmeasured lower-level mediator-outcome confounding" assumption.

On the Interpretation and Use of Mediation: Multiple Perspectives on Mediation Analysis

PubMed Central

Agler, Robert; De Boeck, Paul

2017-01-01

Mediation analysis has become a very popular approach in psychology, and it is one that is associated with multiple perspectives that are often at odds, often implicitly. Explicitly discussing these perspectives and their motivations, advantages, and disadvantages can help to provide clarity to conversations and research regarding the use and refinement of mediation models. We discuss five such pairs of perspectives on mediation analysis, their associated advantages and disadvantages, and their implications: with vs. without a mediation hypothesis, specific effects vs. a global model, directness vs. indirectness of causation, effect size vs. null hypothesis testing, and hypothesized vs. alternative explanations. Discussion of the perspectives is facilitated by a small simulation study. Some philosophical and linguistic considerations are briefly discussed, as well as some other perspectives we do not develop here. PMID:29187828

[The effect of self-reflection on depression mediated by hardiness].

PubMed

Nakajima, Miho; Hattori, Yosuke; Tanno, Yoshihiko

2015-10-01

Previous studies have shown that two types of private self-consciousness result in opposing effects on depression; one of which is self-rumination, which leads to maladaptive effect, and the other is self-reflection, which leads to an adaptive effect. Although a number of studies have examined the mechanism of the maladaptive effect of self-rumination, only a few studies have examined the mechanism of the adaptive effect of self-reflection. The present study examined the process of how self-reflection affected depression adaptively, Based on the previous findings, we proposed a hypothetical model assuming that hardiness acts as a mediator of self-reflection. To test the validity of the model, structural equation modeling analysis was performed with the cross-sectional data of 155 undergraduate students. The results. suggest that the hypothetical model is valid. According to the present results and previous findings, it is suggested that self-reflection is associated with low levels of depression and mediated by "rich commitment", one component of hardiness.

Parent-Reported Behavioral and Psychiatric Problems Mediate the Relationship between Sleep-Disordered Breathing and Cognitive Deficits in School-Aged Children.

PubMed

Smith, Dale L; Gozal, David; Hunter, Scott J; Kheirandish-Gozal, Leila

2017-01-01

Numerous studies over the past several decades have illustrated that children who suffer from sleep-disordered breathing (SDB) are at greater risk for cognitive, behavioral, and psychiatric problems. Although behavioral problems have been proposed as a potential mediator between SDB and cognitive functioning, these relationships have not been critically examined. This analysis is based on a community-based cohort of 1,115 children who underwent overnight polysomnography, and cognitive and behavioral phenotyping. Structural model of the relationships between SDB, behavior, and cognition, and two recently developed mediation approaches based on propensity score weighting and resampling were used to assess the mediational role of parent-reported behavior and psychiatric problems in the relationship between SDB and cognitive functioning. Multiple models utilizing two different SDB definitions further explored direct effects of SDB on cognition as well as indirect effects through behavioral pathology. All models were adjusted for age, sex, race, BMI z -score, and asthma status. Indirect effects of SDB through behavior problems were significant in all mediation models, while direct effects of SDB on cognition were not. The findings were consistent across different mediation procedures and remained essentially unaltered when different criteria for SDB, behavior, and cognition were used. Potential effects of SDB on cognitive functioning appear to occur through behavioral problems that are detectable in this pediatric population. Thus, early attentional or behavioral pathology may be implicated in the cognitive functioning deficits associated with SDB, and may present an early morbidity-related susceptibility biomarker.

Work–Family Conflict and Mental Health Among Female Employees: A Sequential Mediation Model via Negative Affect and Perceived Stress

PubMed Central

Zhou, Shiyi; Da, Shu; Guo, Heng; Zhang, Xichao

2018-01-01

After the implementation of the universal two-child policy in 2016, more and more working women have found themselves caught in the dilemma of whether to raise a baby or be promoted, which exacerbates work–family conflicts among Chinese women. Few studies have examined the mediating effect of negative affect. The present study combined the conservation of resources model and affective events theory to examine the sequential mediating effect of negative affect and perceived stress in the relationship between work–family conflict and mental health. A valid sample of 351 full-time Chinese female employees was recruited in this study, and participants voluntarily answered online questionnaires. Pearson correlation analysis, structural equation modeling, and multiple mediation analysis were used to examine the relationships between work–family conflict, negative affect, perceived stress, and mental health in full-time female employees. We found that women’s perceptions of both work-to-family conflict and family-to-work conflict were significant negatively related to mental health. Additionally, the results showed that negative affect and perceived stress were negatively correlated with mental health. The 95% confidence intervals indicated the sequential mediating effect of negative affect and stress in the relationship between work–family conflict and mental health was significant, which supported the hypothesized sequential mediation model. The findings suggest that work–family conflicts affected the level of self-reported mental health, and this relationship functioned through the two sequential mediators of negative affect and perceived stress. PMID:29719522

Work-Family Conflict and Mental Health Among Female Employees: A Sequential Mediation Model via Negative Affect and Perceived Stress.

PubMed

Zhou, Shiyi; Da, Shu; Guo, Heng; Zhang, Xichao

2018-01-01

After the implementation of the universal two-child policy in 2016, more and more working women have found themselves caught in the dilemma of whether to raise a baby or be promoted, which exacerbates work-family conflicts among Chinese women. Few studies have examined the mediating effect of negative affect. The present study combined the conservation of resources model and affective events theory to examine the sequential mediating effect of negative affect and perceived stress in the relationship between work-family conflict and mental health. A valid sample of 351 full-time Chinese female employees was recruited in this study, and participants voluntarily answered online questionnaires. Pearson correlation analysis, structural equation modeling, and multiple mediation analysis were used to examine the relationships between work-family conflict, negative affect, perceived stress, and mental health in full-time female employees. We found that women's perceptions of both work-to-family conflict and family-to-work conflict were significant negatively related to mental health. Additionally, the results showed that negative affect and perceived stress were negatively correlated with mental health. The 95% confidence intervals indicated the sequential mediating effect of negative affect and stress in the relationship between work-family conflict and mental health was significant, which supported the hypothesized sequential mediation model. The findings suggest that work-family conflicts affected the level of self-reported mental health, and this relationship functioned through the two sequential mediators of negative affect and perceived stress.

Treatment mechanism in the MRC preschool autism communication trial: implications for study design and parent-focussed therapy for children.

PubMed

Pickles, Andrew; Harris, Victoria; Green, Jonathan; Aldred, Catherine; McConachie, Helen; Slonims, Vicky; Le Couteur, Ann; Hudry, Kristelle; Charman, Tony

2015-02-01

The PACT randomised-controlled trial evaluated a parent-mediated communication-focused treatment for children with autism, intended to reduce symptom severity as measured by a modified Autism Diagnostic Observation Schedule-Generic (ADOS-G) algorithm score. The therapy targeted parental behaviour, with no direct interaction between therapist and child. While nonsignificant group differences were found on ADOS-G score, significant group differences were found for both parent and child intermediate outcomes. This study aimed to better understand the mechanism by which the PACT treatment influenced changes in child behaviour though the targeted parent behaviour. Mediation analysis was used to assess the direct and indirect effects of treatment via parent behaviour on child behaviour and via child behaviour on ADOS-G score. Alternative mediation was explored to study whether the treatment effect acted as hypothesised or via another plausible pathway. Mediation models typically assume no unobserved confounding between mediator and outcome and no measurement error in the mediator. We show how to better exploit the information often available within a trial to begin to address these issues, examining scope for instrumental variable and measurement error models. Estimates of mediation changed substantially when account was taken of the confounder effects of the baseline value of the mediator and of measurement error. Our best estimates that accounted for both suggested that the treatment effect on the ADOS-G score was very substantially mediated by parent synchrony and child initiations. The results highlighted the value of repeated measurement of mediators during trials. The theoretical model underlying the PACT treatment was supported. However, the substantial fall-off in treatment effect highlighted both the need for additional data and for additional target behaviours for therapy. © 2014 The Authors. Journal of Child Psychology and Psychiatry. © 2014 Association for Child and Adolescent Mental Health.

A Model of Sexual Abuse's Effects on Suicidal Behavior and Delinquency: The Role of Emotions as Mediating Factors

ERIC Educational Resources Information Center

Sigfusdottir, Inga Dora; Asgeirsdottir, Bryndis Bjork; Gudjonsson, Gisli H.; Sigurdsson, Jon Fridrik

2008-01-01

Drawing on Agnew's general strain theory, we examined whether depressed mood and anger mediated the effects of sexual abuse on suicidal behavior and delinquency. Participants included 9,113 students attending high schools in Iceland. Structural equation modeling showed that, while controlling for family structure and parental education, being…

Reconceptualizing decisional balance in an adolescent sun protection intervention: mediating effects and theoretical interpretations.

PubMed

Adams, Marc A; Norman, Gregory J; Hovell, Melbourne F; Sallis, James F; Patrick, Kevin

2009-03-01

The Transtheoretical model (TTM) integrates principles of operant learning, such as stimulus control and reinforcement, and psychological factors, such as decisional balance. Understanding interrelationships between decisions, behavior, and consequences from multiple-theoretical perspectives can advance theory and inform development of more effective interventions. This analysis examined the mediating effects of a special case of the decisional balance construct in which the pros of competing behaviors (i.e., sun protection vs. exposure) were measured rather than the pros and cons of the same behavior. Participants included 819 adolescents (10 to 16 years old, 53.5% girls, 58.4% White) randomized to a 24-month expert system intervention (SunSmart) or a physical activity and nutrition comparison group. Self-report measures included sun protection behaviors, pros for protection, and pros for exposure. Mediation analysis using latent growth curve models found both the treatment-to-mediator and mediator-to-behavior paths significant for decisional balance, producing an indirect effect of .323 (p < .01) and good model fit (CFI = .973, RMSEA = .055). Multiple strategies for conceptualizing and measuring decisional balance appear to be valid. Results are interpreted from the TTM and operant perspectives. (c) 2009 APA, all rights reserved

In the process of drinking to cope among college students: An examination of specific vs. global coping motives for depression and anxiety symptoms.

PubMed

Bravo, Adrian J; Pearson, Matthew R

2017-10-01

The present study sought to address an issue in the drinking to cope (DTC) motives literature, namely the inconsistent application of treating DTC motives as a single construct and splitting it into DTC-depression and DTC-anxiety motives. Specifically, we aimed to determine if the effects of anxiety and depression on alcohol-related problems are best explained via their associations with DTC with specific affects or via their associations with a more global measure of DTC by testing four distinct models: the effects of anxiety/depression on alcohol-related problems mediated by DTC-anxiety only (Model 1), these effects mediated by DTC-depression only (Model 2), these effects mediated by a combined, global DTC factor (Model 3), and these effects mediated by both DTC-anxiety and DTC-depression (Model 4). Using path analysis/structural equation modeling across two independent samples, we found that there was a significant total indirect effect of both anxiety and depressive symptoms on alcohol-related problems in every model. However, there was a slightly larger indirect effect in all models using the global DTC motives factor compared to even the model that included the two distinct DTC motives. Our results provide some preliminary evidence that at least at the between-subjects level, a global DTC motives factor may have more predictive validity than separate DTC motives. Additional research is needed to examine how to best operationalize DTC motives at different levels of analysis (e.g., within-subjects vs. between subjects) and in different populations (e.g., college students vs. individuals with alcohol use disorder). Copyright © 2017. Published by Elsevier Ltd.

The mediating effect of emotional intelligence between emotional labour, job stress, burnout and nurses' turnover intention.

PubMed

Hong, Eunyoung; Lee, Young Sook

2016-12-01

This study was designed to construct and test the structural equation modelling on nurses' turnover intention including emotional labour, job stress, emotional intelligence and burnout in order to identify the mediating effect of emotional intelligence between those variables. Emotional labour, job stress and burnout increase turnover intention of nurses. However, emotional intelligence is negatively correlated with emotional labour and reduces job stress, burnout and turnover intention. Structural equation modelling was used to analyse the goodness of fit of the hypothetical model of nurses' turnover intention. Research data were collected via questionnaires from 4 to 22 August 2014 and analysed using SPSS version 18.0 and AMOS version 20.0. The model fit indices for the hypothetical model were suitable for recommended. Emotional intelligence has decreasing effect on turnover intention through burnout, although its direct effect on turnover intention is not significant. Emotional intelligence has mediation effect between emotional labour and burnout. This study's results suggest that increasing emotional intelligence might critically decrease nurses' turnover intention by reducing the effect of emotional labour on burnout. © 2016 John Wiley & Sons Australia, Ltd.

Utilized social support and self-esteem mediate the relationship between perceived social support and suicide ideation. A test of a multiple mediator model.

PubMed

Kleiman, Evan M; Riskind, John H

2013-01-01

While perceived social support has received considerable research as a protective factor for suicide ideation, little attention has been given to the mechanisms that mediate its effects. We integrated two theoretical models, Joiner's (2005) interpersonal theory of suicide and Leary's (Leary, Tambor, Terdal, & Downs, 1995) sociometer theory of self-esteem to investigate two hypothesized mechanisms, utilization of social support and self-esteem. Specifically, we hypothesized that individuals must utilize the social support they perceive that would result in increased self-esteem, which in turn buffers them from suicide ideation. Participants were 172 college students who completed measures of social support, self-esteem, and suicide ideation. Tests of simple mediation indicate that utilization of social support and self-esteem may each individually help to mediate the perceived social support/suicide ideation relationship. Additionally, a test of multiple mediators using bootstrapping supported the hypothesized multiple-mediator model. The use of a cross-sectional design limited our ability to find true cause-and-effect relationships. Results suggested that utilized social support and self-esteem both operate as individual moderators in the social support/self-esteem relationship. Results further suggested, in a comprehensive model, that perceived social support buffers suicide ideation through utilization of social support and increases in self-esteem.

Explaining the effects of a 1-year intervention promoting a low fat diet in adolescent girls: a mediation analysis.

PubMed

Haerens, Leen; Cerin, Ester; Deforche, Benedicte; Maes, Lea; De Bourdeaudhuij, Ilse

2007-11-09

Although it is important to investigate how interventions work, no formal mediation analyses have been conducted to explain behavioral outcomes in school-based fat intake interventions in adolescents. The aim of the present study was to examine mediation effects of changes in psychosocial determinants of dietary fat intake (attitude, social support, self-efficacy, perceived benefits and barriers) on changes in fat intake in adolescent girls. Data from a 1-year prospective intervention study were used. A random sample of 804 adolescent girls was included in the study. Girls in the intervention group (n = 415) were exposed to a multi-component school-based intervention program, combining environmental changes with a computer tailored fat intake intervention and parental support. Fat intake and psychosocial determinants of fat intake were measured with validated self-administered questionnaires. To assess mediating effects, a product-of-coefficient test, appropriate for cluster randomized controlled trials, was used. None of the examined psychosocial factors showed a reliable mediating effect on changes in fat intake. The single-mediator model revealed a statistically significant suppression effect of perceived barriers on changes in fat intake (p = 0.011). In the multiple-mediator model, this effect was no longer significant, which was most likely due to changes in perceived barriers being moderately related to changes in self-efficacy (-0.30) and attitude (-0.25). The overall mediated-suppressed effect of the examined psychosocial factors was virtually zero (total mediated effect = 0.001; SE = 7.22; p = 0.992). Given the lack of intervention effects on attitudes, social support, self-efficacy and perceived benefits and barriers, it is suggested that future interventions should focus on the identification of effective strategies for changing these theoretical mediators in the desired direction. Alternatively, it could be argued that these constructs need not be targeted in interventions aimed at adolescents, as they may not be responsible for the intervention effects on fat intake. To draw any conclusions regarding mediators of fat-intake change in adolescent' girls and regarding optimal future intervention strategies, more systematic research on the mediating properties of psychosocial variables is needed.

Neighborhoods, Schools, and Academic Achievement: A Formal Mediation Analysis of Contextual Effects on Reading and Mathematics Abilities.

PubMed

Wodtke, Geoffrey T; Parbst, Matthew

2017-10-01

Although evidence indicates that neighborhoods affect educational outcomes, relatively little research has explored the mechanisms thought to mediate these effects. This study investigates whether school poverty mediates the effect of neighborhood context on academic achievement. Specifically, it uses longitudinal data from the Panel Study of Income Dynamics, counterfactual methods, and a value-added modeling strategy to estimate the total, natural direct, and natural indirect effects of exposure to an advantaged rather than disadvantaged neighborhood on reading and mathematics abilities during childhood and adolescence. Contrary to expectations, results indicate that school poverty is not a significant mediator of neighborhood effects during either developmental period. Although moving from a disadvantaged neighborhood to an advantaged neighborhood is estimated to substantially reduce subsequent exposure to school poverty and improve academic achievement, school poverty does not play an important mediating role because even the large differences in school composition linked to differences in neighborhood context appear to have no appreciable effect on achievement. An extensive battery of sensitivity analyses indicates that these results are highly robust to unobserved confounding, alternative model specifications, alternative measures of school context, and measurement error, which suggests that neighborhood effects on academic achievement are largely due to mediating factors unrelated to school poverty.

A Social Operational Model of Urban Adolescents' Tobacco and Substance Use: A Mediational Analysis

ERIC Educational Resources Information Center

Mason, Michael J.; Mennis, Jeremy; Schmidt, Christopher D.

2011-01-01

This study tested a mediation model of the relationship with tobacco use, social network quality (level of risk or protection in a network), and substance use (alcohol and/or illicit drugs) with a sample of 301 urban adolescents. It was theorized that social network quality would mediate the effect of tobacco use, accounting for PTSD symptoms and…

Poor health and loneliness in later life: the role of depressive symptoms, social resources, and rural environments.

PubMed

Burholt, Vanessa; Scharf, Thomas

2014-03-01

We draw on cognitive discrepancy theory to hypothesize and test a pathway from poor health to loneliness in later life. We hypothesize that poor health will have a negative influence on social participation and social resources, and these factors will mediate between health and loneliness. We hypothesize that rural environments will amplify any difficulties associated with social participation or accessing social resources and that depression will moderate how intensely people react to levels of social contact and support. We conceptualize a mediation model and a moderated-mediation model. Nationally representative data on older people living in the Republic of Ireland are used to validate the hypothesized pathways. In the mediation model, health has a significant indirect effect on loneliness through the mediating variables social resources and social participation. In the moderated-mediation model, rurality moderates the pathway between health and social resources but not social participation. Depressive symptoms moderate the effect of social resources on loneliness but not social participation. The results provide further credence to cognitive discrepancy theory, suggesting that depressive symptoms influence cognitive processes, interfering with judgments about the adequacy of social interaction. The theory is extended by demonstrating the impact of the environment on loneliness.

Assessing moderated mediation in linear models requires fewer confounding assumptions than assessing mediation.

PubMed

Loeys, Tom; Talloen, Wouter; Goubert, Liesbet; Moerkerke, Beatrijs; Vansteelandt, Stijn

2016-11-01

It is well known from the mediation analysis literature that the identification of direct and indirect effects relies on strong no unmeasured confounding assumptions of no unmeasured confounding. Even in randomized studies the mediator may still be correlated with unobserved prognostic variables that affect the outcome, in which case the mediator's role in the causal process may not be inferred without bias. In the behavioural and social science literature very little attention has been given so far to the causal assumptions required for moderated mediation analysis. In this paper we focus on the index for moderated mediation, which measures by how much the mediated effect is larger or smaller for varying levels of the moderator. We show that in linear models this index can be estimated without bias in the presence of unmeasured common causes of the moderator, mediator and outcome under certain conditions. Importantly, one can thus use the test for moderated mediation to support evidence for mediation under less stringent confounding conditions. We illustrate our findings with data from a randomized experiment assessing the impact of being primed with social deception upon observer responses to others' pain, and from an observational study of individuals who ended a romantic relationship assessing the effect of attachment anxiety during the relationship on mental distress 2 years after the break-up. © 2016 The British Psychological Society.

Applying causal mediation analysis to personality disorder research.

PubMed

Walters, Glenn D

2018-01-01

This article is designed to address fundamental issues in the application of causal mediation analysis to research on personality disorders. Causal mediation analysis is used to identify mechanisms of effect by testing variables as putative links between the independent and dependent variables. As such, it would appear to have relevance to personality disorder research. It is argued that proper implementation of causal mediation analysis requires that investigators take several factors into account. These factors are discussed under 5 headings: variable selection, model specification, significance evaluation, effect size estimation, and sensitivity testing. First, care must be taken when selecting the independent, dependent, mediator, and control variables for a mediation analysis. Some variables make better mediators than others and all variables should be based on reasonably reliable indicators. Second, the mediation model needs to be properly specified. This requires that the data for the analysis be prospectively or historically ordered and possess proper causal direction. Third, it is imperative that the significance of the identified pathways be established, preferably with a nonparametric bootstrap resampling approach. Fourth, effect size estimates should be computed or competing pathways compared. Finally, investigators employing the mediation method are advised to perform a sensitivity analysis. Additional topics covered in this article include parallel and serial multiple mediation designs, moderation, and the relationship between mediation and moderation. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

Maltreatment and Delinquency in China: Examining and Extending the Intervening Process of General Strain Theory.

PubMed

Gao, Yunjiao; Wong, Dennis S W; Yu, Yanping

2016-01-01

Using a sample of 1,163 adolescents from four middle schools in China, this study explores the intervening process of how adolescent maltreatment is related to delinquency within the framework of general strain theory (GST) by comparing two models. The first model is Agnew's integrated model of GST, which examines the mediating effects of social control, delinquent peer affiliation, state anger, and depression on the relationship between maltreatment and delinquency. Based on this model, with the intent to further explore the mediating effects of state anger and depression and to investigate whether their effects on delinquency can be demonstrated more through delinquent peer affiliation and social control, an extended model (Model 2) is proposed by the authors. The second model relates state anger to delinquent peer affiliation and state depression to social control. By comparing the fit indices and the significance of the hypothesized paths of the two models, the study found that the extended model can better reflect the mechanism of how maltreatment contributes to delinquency, whereas the original integrated GST model only receives partial support because of its failure to find the mediating effects of state negative emotions. © The Author(s) 2014.

Effect of socio-economic status, family smoking and mental health through social network on the substance use potential in adolescents: a mediation analysis.

PubMed

Sajjadi, H; Jorjoran Shushtari, Z; Mahboubi, S; Rafiey, H; Salimi, Y

2018-04-01

Understanding pathways that influence substance use potential (SUP) can help with effective substance use prevention interventions among adolescents. The aim of the present study is to contribute to a better understanding of the SUP of adolescents by examining the mediating role of social network quality in the SUP of Iranian adolescents. A cross-sectional study. Structural equation modeling was conducted to assess the hypothesized model that social network quality would mediate the association of family socio-economic status, a mental health disorder, and family smoking with addiction potential. The model shows a good fit to the data. Social network quality mediated the effect of family smoking on the SUP for boys. A mental health disorder had a positive significant direct effect on addiction potential for both girls and boys. Social network quality mediates the effect of family smoking on boys' addiction potential in the context of Iran. Educational programs based on local societal ways and cultural norms are recommended to change tobacco smoking behavior among family members. In addition, to prevent subsequent substance use among adolescents, more effort is needed to improve their mental health. Copyright © 2018 The Royal Society for Public Health. Published by Elsevier Ltd. All rights reserved.

Assessing Omitted Confounder Bias in Multilevel Mediation Models.

PubMed

Tofighi, Davood; Kelley, Ken

2016-01-01

To draw valid inference about an indirect effect in a mediation model, there must be no omitted confounders. No omitted confounders means that there are no common causes of hypothesized causal relationships. When the no-omitted-confounder assumption is violated, inference about indirect effects can be severely biased and the results potentially misleading. Despite the increasing attention to address confounder bias in single-level mediation, this topic has received little attention in the growing area of multilevel mediation analysis. A formidable challenge is that the no-omitted-confounder assumption is untestable. To address this challenge, we first analytically examined the biasing effects of potential violations of this critical assumption in a two-level mediation model with random intercepts and slopes, in which all the variables are measured at Level 1. Our analytic results show that omitting a Level 1 confounder can yield misleading results about key quantities of interest, such as Level 1 and Level 2 indirect effects. Second, we proposed a sensitivity analysis technique to assess the extent to which potential violation of the no-omitted-confounder assumption might invalidate or alter the conclusions about the indirect effects observed. We illustrated the methods using an empirical study and provided computer code so that researchers can implement the methods discussed.

Inverse odds ratio-weighted estimation for causal mediation analysis.

PubMed

Tchetgen Tchetgen, Eric J

2013-11-20

An important scientific goal of studies in the health and social sciences is increasingly to determine to what extent the total effect of a point exposure is mediated by an intermediate variable on the causal pathway between the exposure and the outcome. A causal framework has recently been proposed for mediation analysis, which gives rise to new definitions, formal identification results and novel estimators of direct and indirect effects. In the present paper, the author describes a new inverse odds ratio-weighted approach to estimate so-called natural direct and indirect effects. The approach, which uses as a weight the inverse of an estimate of the odds ratio function relating the exposure and the mediator, is universal in that it can be used to decompose total effects in a number of regression models commonly used in practice. Specifically, the approach may be used for effect decomposition in generalized linear models with a nonlinear link function, and in a number of other commonly used models such as the Cox proportional hazards regression for a survival outcome. The approach is simple and can be implemented in standard software provided a weight can be specified for each observation. An additional advantage of the method is that it easily incorporates multiple mediators of a categorical, discrete or continuous nature. Copyright © 2013 John Wiley & Sons, Ltd.

Mediator effect of statistical process control between Total Quality Management (TQM) and business performance in Malaysian Automotive Industry

NASA Astrophysics Data System (ADS)

Ahmad, M. F.; Rasi, R. Z.; Zakuan, N.; Hisyamudin, M. N. N.

2015-12-01

In today's highly competitive market, Total Quality Management (TQM) is vital management tool in ensuring a company can success in their business. In order to survive in the global market with intense competition amongst regions and enterprises, the adoption of tools and techniques are essential in improving business performance. There are consistent results between TQM and business performance. However, only few previous studies have examined the mediator effect namely statistical process control (SPC) between TQM and business performance. A mediator is a third variable that changes the association between an independent variable and an outcome variable. This study present research proposed a TQM performance model with mediator effect of SPC with structural equation modelling, which is a more comprehensive model for developing countries, specifically for Malaysia. A questionnaire was prepared and sent to 1500 companies from automotive industry and the related vendors in Malaysia, giving a 21.8 per cent rate. Attempts were made at findings significant impact of mediator between TQM practices and business performance showed that SPC is important tools and techniques in TQM implementation. The result concludes that SPC is partial correlation between and TQM and BP with indirect effect (IE) is 0.25 which can be categorised as high moderator effect.

Emotional eating as a mediator between depression and weight gain.

PubMed

van Strien, Tatjana; Konttinen, Hanna; Homberg, Judith R; Engels, Rutger C M E; Winkens, Laura H H

2016-05-01

Depression is often associated with weight gain but underlying mechanisms are unclear. This study assessed whether three psychological eating styles (emotional eating, external eating and restrained eating) act as mediators between depression and weight gain. We used structural equation modelling to test the hypothesized mediation models in a sample of 298 fathers and 294 mothers by assessing self-reported eating styles (Dutch Eating Behavior Questionnaire), depressive feelings (Depressive Mood List) and body mass index (BMI) at baseline and BMI after five years. In the model with emotional eating we also assessed the moderation effect of 5-HTTLPR genotype in a sub-sample of 520 Caucasians. All analyses were performed separately for the two sexes. Although the overall effect of depression on weight gain was statistically non-significant in both sexes, there was a causal chain between depression, emotional eating and weight gain in the mothers. Depressive symptoms were related to higher emotional eating and emotional eating predicted greater increases in BMI independently of depression. Moreover, the indirect effect (via emotional eating) of depression on BMI change was significant (Beta = 0.18, P = 0.026). This mediation effect was found to be independent of 5-HTTLPR genotype. No such mediation effect was found for the fathers. Further, external eating and restrained eating did not act as mediators between depression and weight gain in either sex. The finding that emotional eating acted as mediator between depression and weight gain in the mothers suggests that obesity interventions should take emotional eating into account. Copyright © 2016 Elsevier Ltd. All rights reserved.

Testing a multiple mediation model of Asian American college students' willingness to see a counselor.

PubMed

Kim, Paul Youngbin; Park, Irene J K

2009-07-01

Adapting the theory of reasoned action, the present study examined help-seeking beliefs, attitudes, and intent among Asian American college students (N = 110). A multiple mediation model was tested to see if the relation between Asian values and willingness to see a counselor was mediated by attitudes toward seeking professional psychological help and subjective norm. A bootstrapping procedure was used to test the multiple mediation model. Results indicated that subjective norm was the sole significant mediator of the effect of Asian values on willingness to see a counselor. The findings highlight the importance of social influences on help-seeking intent among Asian American college students.

A unification of mediation and interaction: a four-way decomposition

PubMed Central

VanderWeele, Tyler J.

2014-01-01

It is shown that the overall effect of an exposure on an outcome, in the presence of a mediator with which the exposure may interact, can be decomposed into four components: (i) the effect of the exposure in the absence of the mediator, (ii) the interactive effect when the mediator is left to what it would be in the absence of exposure, (iii) a mediated interaction, and (iv) a pure mediated effect. These four components, respectively, correspond to the portion of the effect that is due to neither mediation nor interaction, to just interaction (but not mediation), to both mediation and interaction, and to just mediation (but not interaction). This four-way decomposition unites methods that attribute effects to interactions and methods that assess mediation. Certain combinations of these four components correspond to measures for mediation, while other combinations correspond to measures of interaction previously proposed in the literature. Prior decompositions in the literature are in essence special cases of this four-way decomposition. The four-way decomposition can be carried out using standard statistical models, and software is provided to estimate each of the four components. The four-way decomposition provides maximum insight into how much of an effect is mediated, how much is due to interaction, how much is due to both mediation and interaction together, and how much is due to neither. PMID:25000145

Direct and indirect effects of alcohol expectancies through drinking motives on alcohol outcomes among students in Vietnam.

PubMed

Diep, Pham Bich; Schelleman-Offermans, K; Kuntsche, E; De Vries, Nanne; Knibbe, Ronald A

2016-01-01

To investigate whether the links between alcohol expectancies (tension reduction; global positive change; improved cognitive and motor abilities; and change in social behavior) and alcohol outcomes (drinking volume, 6+ drinks, alcohol problems, and symptoms of alcohol dependence) are mediated by drinking motives (social, enhancement, conformity, and coping). A multi-stage sampling strategy was used in four Vietnamese provinces, resulting in a final sample of 4756 students (43.2% females) with mean age 20.6 (SD 1.8) years. Structural equation models, including indirect effects, were estimated for women and men separately. Overall, there were many cases of full mediation (indirect effects range from -0.006 to 0.083 and p-values from <0.05 to <0.001) and little indication of partial mediation (indirect effects range from -0.009 to 0.025 and p-values from <0.05 to <0.001). In both men and women, coping motives most frequently mediated the influence of expectancies on alcohol outcomes. Among men, enhancement motives and, to a lesser extent, social motives also played a role in mediating the effects of expectancies on alcohol outcomes. Among women, full mediation was found far less often and less consistently. By confirming that, in Vietnam, motives mediate the link between expectancies and drinking behavior, this study supports the cultural robustness of a key assumption of the motivational model (i.e. that drinking motives are more closely associated with alcohol use than expectancies). Enhancement, coping and social motives are most frequently found as mediators among male students whereas coping motive only is most frequently found as a mediator among female students. As most of the effects of expectancies were mediated by motives, drinking motives appear to be a promising factor for interventions. Copyright © 2015 Elsevier Ltd. All rights reserved.

Asymptotic and resampling strategies for assessing and comparing indirect effects in multiple mediator models.

PubMed

Preacher, Kristopher J; Hayes, Andrew F

2008-08-01

Hypotheses involving mediation are common in the behavioral sciences. Mediation exists when a predictor affects a dependent variable indirectly through at least one intervening variable, or mediator. Methods to assess mediation involving multiple simultaneous mediators have received little attention in the methodological literature despite a clear need. We provide an overview of simple and multiple mediation and explore three approaches that can be used to investigate indirect processes, as well as methods for contrasting two or more mediators within a single model. We present an illustrative example, assessing and contrasting potential mediators of the relationship between the helpfulness of socialization agents and job satisfaction. We also provide SAS and SPSS macros, as well as Mplus and LISREL syntax, to facilitate the use of these methods in applications.

Improving Our Ability to Evaluate Underlying Mechanisms of Behavioral Onset and Other Event Occurrence Outcomes: A Discrete-Time Survival Mediation Model

PubMed Central

Fairchild, Amanda J.; Abara, Winston E.; Gottschall, Amanda C.; Tein, Jenn-Yun; Prinz, Ronald J.

2015-01-01

The purpose of this article is to introduce and describe a statistical model that researchers can use to evaluate underlying mechanisms of behavioral onset and other event occurrence outcomes. Specifically, the article develops a framework for estimating mediation effects with outcomes measured in discrete-time epochs by integrating the statistical mediation model with discrete-time survival analysis. The methodology has the potential to help strengthen health research by targeting prevention and intervention work more effectively as well as by improving our understanding of discretized periods of risk. The model is applied to an existing longitudinal data set to demonstrate its use, and programming code is provided to facilitate its implementation. PMID:24296470

Adolescent survivors of childhood sexual abuse: the mediating role of attachment style and coping in psychological and interpersonal functioning.

PubMed

Shapiro, D L; Levendosky, A A

1999-11-01

To examine attachment style and coping strategies as potential mediating variables between childhood sexual abuse (CSA) and psychological and interpersonal functioning in an attempt to explain variability in extent of disorder and level of functioning. Eighty adolescent females, aged 14-16 years, answered questions regarding abuse history, attachment style, coping with an interpersonal stressor, depression and trauma symptomatology, and conflict with a best friend. Structural equation modeling analyses indicated that attachment style mediates the effects of CSA and child abuse and neglect on coping and psychological distress. The indirect effects of CSA and other abuse through attachment accounted for most of the effects on coping and psychological distress. Avoidant and cognitive coping strategies also served as mediators in the models, accounting for most of the effects of the other variables on interpersonal conflict. The findings indicate that attachment style and coping strategies influence psychological and interpersonal functioning, mediating the direct effects of CSA and other types of child abuse and neglect. These results have implications for therapeutic intervention with children and adolescents who have experienced child abuse.

The role of burnout syndrome as a mediator for the effect of psychosocial risk factors on the intensity of musculoskeletal disorders: a structural equation modeling approach.

PubMed

Gholami, Tahereh; Pahlavian, Ahmad Heidari; Akbarzadeh, Mahdi; Motamedzade, Majid; Moghaddam, Rashid Heidari

2016-01-01

This study examined the hypothesis that burnout syndrome mediates effects of psychosocial risk factors and intensity of musculoskeletal disorders (MSDs) among hospital nurses. The sample was composed of 415 nurses from various wards across five hospitals of Iran's Hamedan University of Medical Sciences. Data were collected through three questionnaires: job content questionnaire, Maslach burnout inventory and visual analogue scale. Results of structural equation modeling with a mediating effect showed that psychosocial risk factors were significantly related to changes in burnout, which in turn affects intensity of MSDs.

The Relationship between Authoritarian Leadership and Employees' Deviant Workplace Behaviors: The Mediating Effects of Psychological Contract Violation and Organizational Cynicism.

PubMed

Jiang, Hongyan; Chen, Yang; Sun, Peizhen; Yang, Jun

2017-01-01

This study investigated the relationship between authoritarian leadership and employees' deviant workplace behaviors (DWB), as well as the mediating effects of psychological contract violation and organizational cynicism. A cross-sectional survey was conducted among 391 manufacturing workers in a northern city of China. Structural equation modeling was performed to test the theory-driven models. The results showed that the relationship between authoritarian leadership and employees' DWB was mediated by organizational cynicism. Moreover, this relationship was also sequentially mediated by psychological contract violation and organizational cynicism. This research unveiled psychological contract violation and organizational cynicism as underlying mechanism that explained the link between authoritarian leadership and employees' DWB.

A Note on Testing Mediated Effects in Structural Equation Models: Reconciling Past and Current Research on the Performance of the Test of Joint Significance

ERIC Educational Resources Information Center

Valente, Matthew J.; Gonzalez, Oscar; Miocevic, Milica; MacKinnon, David P.

2016-01-01

Methods to assess the significance of mediated effects in education and the social sciences are well studied and fall into two categories: single sample methods and computer-intensive methods. A popular single sample method to detect the significance of the mediated effect is the test of joint significance, and a popular computer-intensive method…

Children's hostile attribution bias is reduced after watching realistic playful fighting, and the effect is mediated by prosocial thoughts.

PubMed

Boulton, Michael J

2012-09-01

Hostile attribution bias (HAB) has been found to characterize aggressive children. Watching prosocial media has been shown to have positive effects on children, and the general learning model has been used to account for these observations. This study tested the hypotheses derived from this theory that exposure to playful fighting would lead to a reduction in HAB, both immediately and after a 1-day delay, and that this effect would be mediated by positive thoughts. Four studies exposed child participants (N=242) to playful fighting versus neutral behavior primes and then tested their HAB. In two studies, thoughts about playful fighting and about children were assessed and tested as mediators. The main hypotheses were supported. The positive effect of watching playful fighting on HAB was evident immediately but not after 1 day. This effect was mediated by positive thoughts. In line with the general learning model, watching playful fighting reduced HAB in children, and positive thoughts contribute to this effect. This extends the realm of the general learning model and suggests interventions to help children avoid aggression. Copyright © 2012. Published by Elsevier Inc.

Using a multilevel mediation model to examine the effects of National Board Certified Teachers on high school science students' cognitive engagement

NASA Astrophysics Data System (ADS)

Zaleski, Diana Janet

2011-12-01

The National Board for Professional Teaching Standards claims to identify effective educators through their certification process. However, research concerning National Board Certified Teachers (NBCT) is inconclusive. The purpose of this study was to examine the direct and indirect effects of NBCT on the cognitive engagement of high school science students. Multilevel mediation modeling was used to examine the direct and indirect effects of teacher certification on students' cognitive engagement in science and whether students' expectancies for success and perceptions of task value mediate these effects. Students of NBCT were found to be more cognitively engaged in science than students of non-NBCT; however, students' expectancies for success and perceptions of task value did not mediate this relationship. In addition, students with more positive expectancies for success and perceptions of task value were more cognitively engaged in science. These findings support the proposition that the National Board certification process at least identifies effective educators.

The Health Belief Model as an Explanatory Framework in Communication Research: Exploring Parallel, Serial, and Moderated Mediation

PubMed Central

Jones, Christina L.; Jensen, Jakob D.; Scherr, Courtney L.; Brown, Natasha R.; Christy, Katheryn; Weaver, Jeremy

2015-01-01

The Health Belief Model (HBM) posits that messages will achieve optimal behavior change if they successfully target perceived barriers, benefits, self-efficacy, and threat. While the model seems to be an ideal explanatory framework for communication research, theoretical limitations have limited its use in the field. Notably, variable ordering is currently undefined in the HBM. Thus, it is unclear whether constructs mediate relationships comparably (parallel mediation), in sequence (serial mediation), or in tandem with a moderator (moderated mediation). To investigate variable ordering, adults (N = 1,377) completed a survey in the aftermath of an 8-month flu vaccine campaign grounded in the HBM. Exposure to the campaign was positively related to vaccination behavior. Statistical evaluation supported a model where the indirect effect of exposure on behavior through perceived barriers and threat was moderated by self-efficacy (moderated mediation). Perceived barriers and benefits also formed a serial mediation chain. The results indicate that variable ordering in the Health Belief Model may be complex, may help to explain conflicting results of the past, and may be a good focus for future research. PMID:25010519

Social connectedness, discrimination, and social status as mediators of acculturation/enculturation and well-being.

PubMed

Yoon, Eunju; Hacker, Jason; Hewitt, Amber; Abrams, Matthew; Cleary, Sarah

2012-01-01

The present study proposed and tested a conceptual model of acculturation/enculturation and subjective well-being (SWB) by including social connectedness in mainstream society, social connectedness in the ethnic community, perceived discrimination, and expected social status as mediators. Survey data from 273 Asian American college students in the midwest were analyzed by using structural equation modeling. Results indicated that the effect of acculturation on SWB was mediated by social connectedness in mainstream and ethnic communities and expected social status, whereas the effect of enculturation on SWB was mediated by social connectedness in the ethnic community and expected social status. Contrary to the authors' hypothesis, perceived discrimination did not mediate the relation of acculturation and SWB, but indirectly influenced SWB via a lowered sense of connectedness to mainstream society. Approximately 46% of the variance in SWB was accounted for by the variables included in this model. Implications for theory, research, and practice are discussed. (c) 2012 APA, all rights reserved.

Examining the effects of emotional and cognitive desensitization to community violence exposure in male adolescents of color.

PubMed

Gaylord-Harden, Noni K; So, Suzanna; Bai, Grace J; Tolan, Patrick H

2017-01-01

The current study examined pathways in a model of desensitization, the Pathologic Adaptation Model, in adolescent males of color. Specifically, the current study examined depressive symptoms and deviant beliefs as mediators of the association between community violence exposure and subsequent violent behavior. The current study included 250 African-American (67%) and Latino (33%) male adolescents (T1 mean age = 15.32) from the Chicago Youth Development Study. Consistent with the Pathologic Adaptation Model, results demonstrated that depressive symptoms mediated the association between the quadratic violence exposure term in middle adolescence and violent behaviors in late adolescence, but the direction of the mediation effect was dependent upon the levels of violence exposure in middle adolescence. However, deviant beliefs were not found to be a significant mediator. Emotional desensitization effects may increase the likelihood of violence perpetration in adolescent males exposed to community violence, and the implications for future research and intervention efforts are discussed. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

Examining the Effects of Emotional and Cognitive Desensitization to Community Violence Exposure in Male Adolescents of Color

PubMed Central

Gaylord-Harden, Noni K.; So, Suzanna; Bai, Grace J.; Tolan, Patrick H.

2016-01-01

Objective The current study examined pathways in a model of desensitization, the Pathologic Adaptation Model, in adolescent males of color. Specifically, the current study examined depressive symptoms and deviant beliefs as mediators of the association between community violence exposure and subsequent violent behavior. Method The current study included 250 African American (67%) and Latino (33%) male adolescents (T1 mean age = 15.32) from the Chicago Youth Development Study. Results Consistent with the Pathologic Adaptation Model, results demonstrated that depressive symptoms mediated the association between the quadratic violence exposure term in middle adolescence and violent behaviors in late adolescence, but the direction of the mediation effect was dependent upon the levels of violence exposure in middle adolescence. However, deviant beliefs were not found to be a significant mediator. Conclusion Emotional desensitization effects may increase the likelihood of violence perpetration in adolescent males exposed to community violence, and the implications for future research and intervention efforts are discussed. PMID:27977283

You can hide but you have to run: direct detection with vector mediators

NASA Astrophysics Data System (ADS)

D'Eramo, Francesco; Kavanagh, Bradley J.; Panci, Paolo

2016-08-01

We study direct detection in simplified models of Dark Matter (DM) in which interactions with Standard Model (SM) fermions are mediated by a heavy vector boson. We consider fully general, gauge-invariant couplings between the SM, the mediator and both scalar and fermion DM. We account for the evolution of the couplings between the energy scale of the mediator mass and the nuclear energy scale. This running arises from virtual effects of SM particles and its inclusion is not optional. We compare bounds on the mediator mass from direct detection experiments with and without accounting for the running. In some cases the inclusion of these effects changes the bounds by several orders of magnitude, as a consequence of operator mixing which generates new interactions at low energy. We also highlight the importance of these effects when translating LHC limits on the mediator mass into bounds on the direct detection cross section. For an axial-vector mediator, the running can alter the derived bounds on the spin-dependent DM-nucleon cross section by a factor of two or more. Finally, we provide tools to facilitate the inclusion of these effects in future studies: general approximate expressions for the low energy couplings and a public code runDM to evolve the couplings between arbitrary energy scales.

The Mediating Effect of Gaming Motivation Between Psychiatric Symptoms and Problematic Online Gaming: An Online Survey

PubMed Central

Király, Orsolya; Urbán, Róbert; Griffiths, Mark D; Ágoston, Csilla; Nagygyörgy, Katalin; Kökönyei, Gyöngyi

2015-01-01

Background The rapid expansion of online video gaming as a leisure time activity has led to the appearance of problematic online gaming (POG). According to the literature, POG is associated with different psychiatric symptoms (eg, depression, anxiety) and with specific gaming motives (ie, escape, achievement). Based on studies of alcohol use that suggest a mediator role of drinking motives between distal influences (eg, trauma symptoms) and drinking problems, this study examined the assumption that there is an indirect link between psychiatric distress and POG via the mediation of gaming motives. Furthermore, it was also assumed that there was a moderator effect of gender and game type preference based on the important role gender plays in POG and the structural differences between different game types. Objective This study had two aims. The first aim was to test the mediating role of online gaming motives between psychiatric symptoms and problematic use of online games. The second aim was to test the moderator effect of gender and game type preference in this mediation model. Methods An online survey was conducted on a sample of online gamers (N=3186; age: mean 21.1, SD 5.9 years; male: 2859/3186, 89.74%). The Brief Symptom Inventory (BSI), the Motives for Online Gaming Questionnaire (MOGQ), and the Problematic Online Gaming Questionnaire (POGQ) were administered to assess general psychiatric distress, online gaming motives, and problematic online game use, respectively. Structural regression analyses within structural equation modeling were used to test the proposed mediation models and multigroup analyses were used to test gender and game type differences to determine possible moderating effects. Results The mediation models fitted the data adequately. The Global Severity Index (GSI) of the BSI indicated that the level of psychiatric distress had a significant positive direct effect (standardized effect=.35, P<.001) and a significant indirect (mediating) effect on POG (standardized effect=.194, P<.001) via 2 gaming motives: escape (standardized effect=.139, P<.001) and competition (standardized effect=.046, P<.001). The comparison of the 2 main gamer types showed no significant differences in the model. However, when comparing male and female players it was found that women had (1) slightly higher escape scores (on a 5-point Likert scale: mean 2.28, SD 1.14) than men (mean 1.87, SD 0.97) and (2) a stronger association between the escape motive and problematic online gaming (standardized effect size=.64, P<.001) than men (standardized effect size=.20, P=.001). Conclusions The results suggest that psychiatric distress is both directly and indirectly (via escape and competition motives) negatively associated with POG. Therefore, the exploration of psychiatric symptoms and gaming motives of POG can be helpful in the preparation of prevention and treatment programs. PMID:25855558

The mediating effect of gaming motivation between psychiatric symptoms and problematic online gaming: an online survey.

PubMed

Király, Orsolya; Urbán, Róbert; Griffiths, Mark D; Ágoston, Csilla; Nagygyörgy, Katalin; Kökönyei, Gyöngyi; Demetrovics, Zsolt

2015-04-07

The rapid expansion of online video gaming as a leisure time activity has led to the appearance of problematic online gaming (POG). According to the literature, POG is associated with different psychiatric symptoms (eg, depression, anxiety) and with specific gaming motives (ie, escape, achievement). Based on studies of alcohol use that suggest a mediator role of drinking motives between distal influences (eg, trauma symptoms) and drinking problems, this study examined the assumption that there is an indirect link between psychiatric distress and POG via the mediation of gaming motives. Furthermore, it was also assumed that there was a moderator effect of gender and game type preference based on the important role gender plays in POG and the structural differences between different game types. This study had two aims. The first aim was to test the mediating role of online gaming motives between psychiatric symptoms and problematic use of online games. The second aim was to test the moderator effect of gender and game type preference in this mediation model. An online survey was conducted on a sample of online gamers (N=3186; age: mean 21.1, SD 5.9 years; male: 2859/3186, 89.74%). The Brief Symptom Inventory (BSI), the Motives for Online Gaming Questionnaire (MOGQ), and the Problematic Online Gaming Questionnaire (POGQ) were administered to assess general psychiatric distress, online gaming motives, and problematic online game use, respectively. Structural regression analyses within structural equation modeling were used to test the proposed mediation models and multigroup analyses were used to test gender and game type differences to determine possible moderating effects. The mediation models fitted the data adequately. The Global Severity Index (GSI) of the BSI indicated that the level of psychiatric distress had a significant positive direct effect (standardized effect=.35, P<.001) and a significant indirect (mediating) effect on POG (standardized effect=.194, P<.001) via 2 gaming motives: escape (standardized effect=.139, P<.001) and competition (standardized effect=.046, P<.001). The comparison of the 2 main gamer types showed no significant differences in the model. However, when comparing male and female players it was found that women had (1) slightly higher escape scores (on a 5-point Likert scale: mean 2.28, SD 1.14) than men (mean 1.87, SD 0.97) and (2) a stronger association between the escape motive and problematic online gaming (standardized effect size=.64, P<.001) than men (standardized effect size=.20, P=.001). The results suggest that psychiatric distress is both directly and indirectly (via escape and competition motives) negatively associated with POG. Therefore, the exploration of psychiatric symptoms and gaming motives of POG can be helpful in the preparation of prevention and treatment programs.

Computational nanomedicine: modeling of nanoparticle-mediated hyperthermal cancer therapy

PubMed Central

Kaddi, Chanchala D; Phan, John H; Wang, May D

2016-01-01

Nanoparticle-mediated hyperthermia for cancer therapy is a growing area of cancer nanomedicine because of the potential for localized and targeted destruction of cancer cells. Localized hyperthermal effects are dependent on many factors, including nanoparticle size and shape, excitation wavelength and power, and tissue properties. Computational modeling is an important tool for investigating and optimizing these parameters. In this review, we focus on computational modeling of magnetic and gold nanoparticle-mediated hyperthermia, followed by a discussion of new opportunities and challenges. PMID:23914967

Can we get some cooperation around here? The mediating role of group norms on the relationship between team personality and individual helping behaviors.

PubMed

Gonzalez-Mulé, Erik; DeGeest, David S; McCormick, Brian W; Seong, Jee Young; Brown, Kenneth G

2014-09-01

Drawing on the group-norms theory of organizational citizenship behaviors and person-environment fit theory, we introduce and test a multilevel model of the effects of additive and dispersion composition models of team members' personality characteristics on group norms and individual helping behaviors. Our model was tested using regression and random coefficients modeling on 102 research and development teams. Results indicated that high mean levels of extraversion are positively related to individual helping behaviors through the mediating effect of cooperative group norms. Further, low variance on agreeableness (supplementary fit) and high variance on extraversion (complementary fit) promote the enactment of individual helping behaviors, but only the effects of extraversion were mediated by cooperative group norms. Implications of these findings for theories of helping behaviors in teams are discussed. PsycINFO Database Record (c) 2014 APA, all rights reserved.

Workplace ostracism And workplace behaviors: A moderated mediation model of perceived stress and psychological empowerment.

PubMed

Chung, Yang Woon

2018-05-01

Workplace ostracism research has examined numerous underlying mechanisms to understand the link between workplace ostracism and behavioral outcomes. Ostracism has been suggested to be an interpersonal stressor; however, research has not investigated workplace ostracism from a stress perspective. Therefore, the study investigated the mediating effect of perceived stress for the relationships between workplace ostracism and helping behavior, voicing behavior, and task performance. The study also investigated the moderating effect of psychological empowerment for the relationships between perceived stress and behavioral outcomes. The study design was a three-wave self-reported questionnaire. The study sampled 225 full-time employees in South Korea and regression analyses with bootstrapping were conducted to test the moderated mediation models. The bootstrapped 95% CI around the indirect effects did not contain zero; therefore, perceived stress mediated the relationship between workplace ostracism and helping behavior (-.06), voicing behavior (-.07), and task performance (-.07). Further, the moderated mediation analyses found perceived stress mediated the relationships between workplace ostracism and behavioral outcomes only when individuals perceived low levels of psychological empowerment. The findings suggest that workplace ostracism is a stressor and psychological empowerment can mitigate the negative effects of ostracism on behavioral outcomes.

Mechanisms of change underlying the efficacy of cognitive behaviour therapy for chronic fatigue syndrome in a specialist clinic: a mediation analysis.

PubMed

Stahl, D; Rimes, K A; Chalder, T

2014-04-01

Several randomized controlled trials (RCTs) have shown that cognitive behavioural psychotherapy (CBT) is an efficacious treatment for chronic fatigue syndrome (CFS). However, little is known about the mechanisms by which the treatment has its effect. The aim of this study was to investigate potential mechanisms of change underlying the efficacy of CBT for CFS. We applied path analysis and introduce novel model comparison approaches to assess a theoretical CBT model that suggests that fearful cognitions will mediate the relationship between avoidance behaviour and illness outcomes (fatigue and social adjustment). Data from 389 patients with CFS who received CBT in a specialist service in the UK were collected at baseline, at discharge from treatment, and at 3-, 6- and 12-month follow-ups. Path analyses were used to assess possible mediating effects. Model selection using information criteria was used to compare support for competing mediational models. Path analyses were consistent with the hypothesized model in which fear avoidance beliefs at the 3-month follow-up partially mediate the relationship between avoidance behaviour at discharge and fatigue and social adjustment respectively at 6 months. The results strengthen the validity of a theoretical model of CBT by confirming the role of cognitive and behavioural factors in CFS.

Religiosity and decreased risk of substance use disorders: is the effect mediated by social support or mental health status?

PubMed Central

Harris, Katherine M.; Koenig, Harold G.; Han, Xiaotong; Sullivan, Greer; Mattox, Rhonda; Tang, Lingqi

2009-01-01

Objective The negative association between religiosity (religious beliefs and church attendance) and the likelihood of substance use disorders is well established, but the mechanism(s) remain poorly understood. We investigated whether this association was mediated by social support or mental health status. Method We utilized cross-sectional data from the 2002 National Survey on Drug Use and Health (n = 36,370). We first used logistic regression to regress any alcohol use in the past year on sociodemographic and religiosity variables. Then, among individuals who drank in the past year, we regressed past year alcohol abuse/dependence on sociodemographic and religiosity variables. To investigate whether social support mediated the association between religiosity and alcohol use and alcohol abuse/dependence we repeated the above models, adding the social support variables. To the extent that these added predictors modified the magnitude of the effect of the religiosity variables, we interpreted social support as a possible mediator. We also formally tested for mediation using path analysis. We investigated the possible mediating role of mental health status analogously. Parallel sets of analyses were conducted for any drug use, and drug abuse/dependence among those using any drugs as the dependent variables. Results The addition of social support and mental health status variables to logistic regression models had little effect on the magnitude of the religiosity coefficients in any of the models. While some of the tests of mediation were significant in the path analyses, the results were not always in the expected direction, and the magnitude of the effects was small. Conclusions The association between religiosity and decreased likelihood of a substance use disorder does not appear to be substantively mediated by either social support or mental health status. PMID:19714282

Compulsory citizenship behavior and organizational citizenship behavior: the role of organizational identification and perceived interactional justice.

PubMed

Zhao, Hongdan; Peng, Zhenglong; Chen, Hsiu-Kuei

2014-01-01

This article examines the psychological mechanism underlying the relationship between compulsory citizenship behavior (CCB) and organizational citizenship behavior (OCB) by developing a moderated mediation model. The model focuses on the mediating role of organizational identification and the moderating role of interactional justice in influencing the mediation. Using a time-lagged research design, the authors collected two waves of data from 388 supervisor-subordinate dyads in 67 teams to test the moderated mediation model. Results revealed that CCB negatively influenced OCB via impairing organizational identification. Moreover, interactional justice moderated the strength of the indirect effect of CCB on OCB (through organizational identification), such that the mediated relationship was stronger under low interactional justice than under high interactional justice.

Neuroticism, conscientiousness and fruit consumption: exploring mediator and moderator effects in the theory of planned behaviour.

PubMed

de Bruijn, Gert-Jan; Brug, Johannes; Van Lenthe, Frank J

2009-11-01

Integrating the theory of planned behaviour (TPB) with the five-factor model (FFM) of personality may provide insight into the cognitive and motivational mechanisms linking personality with health behaviour, but this issue has received very little attention regarding fruit consumption. Mediator effects of TPB concepts in the personality-fruit consumption link, as well as moderator effects of personality in the intention-fruit consumption link, were therefore investigated in the present study. Data on fruit consumption, TPB concepts and FFM dimensions were gathered among 405 respondents in face-to-face interviews using questionnaires. Structural equation modelling was used to investigate the mediator and moderator effects. The direct effect of conscientiousness on fruit consumption was mediated by attitude and perceived behavioural control, while no direct effect of neuroticism on fruit consumption was found. Neuroticism moderated the intention-fruit consumption relationship with the weakest relationship for those scoring high on neuroticism. Conscientiousness did not moderate the intention-fruit consumption relationship. TPB variables are mediators in the conscientiousness-fruit consumption link. Whether fruit consumption is intentional may be dependent upon the personality dimension neuroticism. Personality dimensions may be a useful addition to the TPB and should be considered in health behaviour change interventions.

Trends in Mediation Analysis in Nursing Research: Improving Current Practice.

PubMed

Hertzog, Melody

2018-06-01

The purpose of this study was to describe common approaches used by nursing researchers to test mediation models and evaluate them within the context of current methodological advances. MEDLINE was used to locate studies testing a mediation model and published from 2004 to 2015 in nursing journals. Design (experimental/correlation, cross-sectional/longitudinal, model complexity) and analysis (method, inclusion of test of mediated effect, violations/discussion of assumptions, sample size/power) characteristics were coded for 456 studies. General trends were identified using descriptive statistics. Consistent with findings of reviews in other disciplines, evidence was found that nursing researchers may not be aware of the strong assumptions and serious limitations of their analyses. Suggestions for strengthening the rigor of such studies and an overview of current methods for testing more complex models, including longitudinal mediation processes, are presented.

SPSS and SAS procedures for estimating indirect effects in simple mediation models.

PubMed

Preacher, Kristopher J; Hayes, Andrew F

2004-11-01

Researchers often conduct mediation analysis in order to indirectly assess the effect of a proposed cause on some outcome through a proposed mediator. The utility of mediation analysis stems from its ability to go beyond the merely descriptive to a more functional understanding of the relationships among variables. A necessary component of mediation is a statistically and practically significant indirect effect. Although mediation hypotheses are frequently explored in psychological research, formal significance tests of indirect effects are rarely conducted. After a brief overview of mediation, we argue the importance of directly testing the significance of indirect effects and provide SPSS and SAS macros that facilitate estimation of the indirect effect with a normal theory approach and a bootstrap approach to obtaining confidence intervals, as well as the traditional approach advocated by Baron and Kenny (1986). We hope that this discussion and the macros will enhance the frequency of formal mediation tests in the psychology literature. Electronic copies of these macros may be downloaded from the Psychonomic Society's Web archive at www.psychonomic.org/archive/.

Mediation and moderation of treatment effects in randomised controlled trials of complex interventions.

PubMed

Emsley, Richard; Dunn, Graham; White, Ian R

2010-06-01

Complex intervention trials should be able to answer both pragmatic and explanatory questions in order to test the theories motivating the intervention and help understand the underlying nature of the clinical problem being tested. Key to this is the estimation of direct effects of treatment and indirect effects acting through intermediate variables which are measured post-randomisation. Using psychological treatment trials as an example of complex interventions, we review statistical methods which crucially evaluate both direct and indirect effects in the presence of hidden confounding between mediator and outcome. We review the historical literature on mediation and moderation of treatment effects. We introduce two methods from within the existing causal inference literature, principal stratification and structural mean models, and demonstrate how these can be applied in a mediation context before discussing approaches and assumptions necessary for attaining identifiability of key parameters of the basic causal model. Assuming that there is modification by baseline covariates of the effect of treatment (i.e. randomisation) on the mediator (i.e. covariate by treatment interactions), but no direct effect on the outcome of these treatment by covariate interactions leads to the use of instrumental variable methods. We describe how moderation can occur through post-randomisation variables, and extend the principal stratification approach to multiple group methods with explanatory models nested within the principal strata. We illustrate the new methodology with motivating examples of randomised trials from the mental health literature.

An exponential decay model for mediation.

PubMed

Fritz, Matthew S

2014-10-01

Mediation analysis is often used to investigate mechanisms of change in prevention research. Results finding mediation are strengthened when longitudinal data are used because of the need for temporal precedence. Current longitudinal mediation models have focused mainly on linear change, but many variables in prevention change nonlinearly across time. The most common solution to nonlinearity is to add a quadratic term to the linear model, but this can lead to the use of the quadratic function to explain all nonlinearity, regardless of theory and the characteristics of the variables in the model. The current study describes the problems that arise when quadratic functions are used to describe all nonlinearity and how the use of nonlinear functions, such as exponential decay, address many of these problems. In addition, nonlinear models provide several advantages over polynomial models including usefulness of parameters, parsimony, and generalizability. The effects of using nonlinear functions for mediation analysis are then discussed and a nonlinear growth curve model for mediation is presented. An empirical example using data from a randomized intervention study is then provided to illustrate the estimation and interpretation of the model. Implications, limitations, and future directions are also discussed.

An Exponential Decay Model for Mediation

PubMed Central

Fritz, Matthew S.

2013-01-01

Mediation analysis is often used to investigate mechanisms of change in prevention research. Results finding mediation are strengthened when longitudinal data are used because of the need for temporal precedence. Current longitudinal mediation models have focused mainly on linear change, but many variables in prevention change nonlinearly across time. The most common solution to nonlinearity is to add a quadratic term to the linear model, but this can lead to the use of the quadratic function to explain all nonlinearity, regardless of theory and the characteristics of the variables in the model. The current study describes the problems that arise when quadratic functions are used to describe all nonlinearity and how the use of nonlinear functions, such as exponential decay, addresses many of these problems. In addition, nonlinear models provide several advantages over polynomial models including usefulness of parameters, parsimony, and generalizability. The effects of using nonlinear functions for mediation analysis are then discussed and a nonlinear growth curve model for mediation is presented. An empirical example using data from a randomized intervention study is then provided to illustrate the estimation and interpretation of the model. Implications, limitations, and future directions are also discussed. PMID:23625557

A Survey of the Effect of Leader's Social Intelligence on Employee's Perception of Interpersonal Justice: The Mediating Role of Shared Leadership

ERIC Educational Resources Information Center

Nazarpoori, Amirhooshang

2017-01-01

The purpose of this study was to investigate the effect of a leader's social intelligence (SI) on an employee's perception of interpersonal justice by considering the mediating role of shared leadership. Conceptual model and research hypotheses have been developed by the Marlowe's SI model (1986), and the theory of shared leadership and…

Internalized stigma and quality of life domains among people with mental illness: the mediating role of self-esteem.

PubMed

Oliveira, Sandra E H; Carvalho, Helena; Esteves, Francisco

2016-01-01

People with mental illness who internalize stigma often experience reduced self-esteem and impaired quality of life (QOL). To propose a theoretical model in which self-esteem mediates the effects of internalized stigma on the multidimensional domains comprising QOL. In 403 inpatients and outpatients (DSM-IV, American Psychiatric Association, 1994), from hospital-based and community mental health facilities, self-report measures of internalized stigma (ISMI), self-esteem (RSES) and QOL (WHOQOL-Bref) were administrated. Structural equation modeling results supported the proposed model. Self-esteem fully mediated the relation between internalized stigma and the physical and the social relationships domains, and partially mediated the relationship between internalized stigma and psychological, environment and level of independence QOL domains. Such results provided empirical support and shed light upon previous research. Specifically the results emphasize the mediating role that self-esteem plays in the degree to which internalized stigma exerts a negative effect on specific QOL domains. Self-esteem appears to be a core element in reducing the negative effects of internalized stigma on aspects of QOL among people with mental illness. These findings suggest there is a crucial impact regarding clinical mental health interventions along with important theoretical implications.

Poor Health and Loneliness in Later Life: The Role of Depressive Symptoms, Social Resources, and Rural Environments

PubMed Central

2014-01-01

Objectives. We draw on cognitive discrepancy theory to hypothesize and test a pathway from poor health to loneliness in later life. We hypothesize that poor health will have a negative influence on social participation and social resources, and these factors will mediate between health and loneliness. We hypothesize that rural environments will amplify any difficulties associated with social participation or accessing social resources and that depression will moderate how intensely people react to levels of social contact and support. Methods. We conceptualize a mediation model and a moderated-mediation model. Nationally representative data on older people living in the Republic of Ireland are used to validate the hypothesized pathways. Results. In the mediation model, health has a significant indirect effect on loneliness through the mediating variables social resources and social participation. In the moderated-mediation model, rurality moderates the pathway between health and social resources but not social participation. Depressive symptoms moderate the effect of social resources on loneliness but not social participation. Discussion. The results provide further credence to cognitive discrepancy theory, suggesting that depressive symptoms influence cognitive processes, interfering with judgments about the adequacy of social interaction. The theory is extended by demonstrating the impact of the environment on loneliness. PMID:24326076

Negative evaluations of self and others, and peer victimization as mediators of the relationship between childhood adversity and psychotic experiences in adolescence: the moderating role of loneliness.

PubMed

Murphy, Siobhan; Murphy, Jamie; Shevlin, Mark

2015-09-01

Previous research has identified an association between traumatic experiences and psychotic symptoms. Few studies, however, have explored the underlying mechanisms and contingent nature of these associations in an integrated model. This study aimed to test a moderated mediation model of negative childhood experiences, associated cognitive processes, and psychotic experiences within a context of adolescent loneliness. Cross-sectional survey. A total of 785 Northern Irish secondary school adolescents completed the survey. A moderated mediation model was specified and tested. Childhood experiences of threat and subordination were directly associated with psychotic experiences. Analyses indicated that peer victimization was a mediator of this effect and that loneliness moderated this mediated effect. A new model is proposed to provide an alternative framework for assessing the association between trauma and psychotic experience in adolescence that recognizes loneliness as a significant contextual moderator that can potentially strengthen the trauma-psychosis relationship. Moderated mediation analyses poses an alternative framework to the understanding of trauma-psychosis associations Adolescent loneliness is a vulnerability factor within this association Data are based on a Northern Irish sample with relatively low levels of loneliness Cross-sectional data cannot explore the developmental course of these experiences in adolescence. © 2015 The British Psychological Society.

From Family Violence Exposure to Violent Offending: Examining Effects of Race and Mental Health in a Moderated Mediation Model Among Confined Male Juveniles.

PubMed

Fix, Rebecca L; Alexander, Apryl A; Burkhart, Barry R

2017-09-01

Depression, substance use, and impulsivity have been linked to family violence exposure and to the development of violent offending during adolescence. Additionally, the indirect effects associated with these factors may not generalize across different racial/ethnic adolescent populations. The present study tested whether race/ethnicity moderated the mediated relationship between family violence exposure and violent offending, with depression, substance use, and impulsivity as mediators. A sample of 1,359 male adolescents was obtained from a juvenile correctional program. Between-racial/ethnic group comparisons were generally consistent with previous findings. The overall moderated mediation model was significant in predicting violence for both racial/ethnic groups. Different factors influenced violent offending among African Americans and European Americans in the tested model. Furthermore, race/ethnicity moderated the relationship between family violence exposure and impulsivity and substance use. Implications and future directions resolving issues are discussed concerning whether race/ethnicity should be included as a moderator in models of violence.

Maturity associated variance in physical activity and health-related quality of life in adolescent females: a mediated effects model.

PubMed

Smart, Joan E Hunter; Cumming, Sean P; Sherar, Lauren B; Standage, Martyn; Neville, Helen; Malina, Robert M

2012-01-01

This study tested a mediated effects model of psychological and behavioral adaptation to puberty within the context of physical activity (PA). Biological maturity status, physical self-concept, PA, and health-related quality of life (HRQoL) were assessed in 222 female British year 7 to 9 pupils (mean age = 12.7 years, SD = .8). Structural equation modeling using maximum likelihood estimation and bootstrapping procedures supported the hypothesized model. Maturation status was inversely related to perceptions of sport competence, body attractiveness, and physical condition; and indirectly and inversely related to physical self-worth, PA, and HRQoL. Examination of the bootstrap-generated bias-corrected confidence intervals representing the direct and indirect paths between suggested that physical self-concept partially mediated the relations between maturity status and PA, and maturity status and HRQoL. Evidence supports the contention that perceptions of the physical self partially mediate relations maturity, PA, and HRQoL in adolescent females.

Relationships Between Self-Efficacy, Self-Esteem and Procrastination in Undergraduate Psychology Students

PubMed Central

Hajloo, Nader

2014-01-01

Objective: The present study aimed to review the relationships between procrastination and two self-factors self-efficacy and self-esteem. Methods: Participants were 140 undergraduates Psychology students enrolled in Mohagheg Ardabili University, Ardabil, Iran. Instruments used for collecting the required data were the student-version of the General Procrastination Scale (GP-S), General Self-Efficacy Scale (GSE) and Rosenberg’s Self-Esteem Scale (SES). Results: Using causal modeling, two models were compared; a model with self-esteem as a mediator versus a model with procrastination as a mediator. The self-esteem mediator model accounted for 21% of the variance in procrastination. The significance of the mediation effect was found by bootstrapping method. Conclusion: The relationship of procrastination with self-esteem and self-efficacy was revealed among undergraduate psychology students. PMID:25780374

Relationships between self-efficacy, self-esteem and procrastination in undergraduate psychology students.

PubMed

Hajloo, Nader

2014-01-01

The present study aimed to review the relationships between procrastination and two self-factors self-efficacy and self-esteem. Participants were 140 undergraduates Psychology students enrolled in Mohagheg Ardabili University, Ardabil, Iran. Instruments used for collecting the required data were the student-version of the General Procrastination Scale (GP-S), General Self-Efficacy Scale (GSE) and Rosenberg's Self-Esteem Scale (SES). Using causal modeling, two models were compared; a model with self-esteem as a mediator versus a model with procrastination as a mediator. The self-esteem mediator model accounted for 21% of the variance in procrastination. The significance of the mediation effect was found by bootstrapping method. The relationship of procrastination with self-esteem and self-efficacy was revealed among undergraduate psychology students.

Patient Expectancy as a Mediator of Placebo Effects in Antidepressant Clinical Trials.

PubMed

Rutherford, Bret R; Wall, Melanie M; Brown, Patrick J; Choo, Tse-Hwei; Wager, Tor D; Peterson, Bradley S; Chung, Sarah; Kirsch, Irving; Roose, Steven P

2017-02-01

Causes of placebo effects in antidepressant trials have been inferred from observational studies and meta-analyses, but their mechanisms have not been directly established. The goal of this study was to examine in a prospective, randomized controlled trial whether patient expectancy mediates placebo effects in antidepressant studies. Adult outpatients with major depressive disorder were randomly assigned to open or placebo-controlled citalopram treatment. Following measurement of pre- and postrandomization expectancy, participants were treated with citalopram or placebo for 8 weeks. Independent samples t tests determined whether patient expectancy differed between the open and placebo-controlled groups, and mixed-effects models assessed group effects on Hamilton Depression Rating Scale (HAM-D) scores over time while controlling for treatment assignment. Finally, mediation analyses tested whether between-group differences in patient expectancy mediated the group effect on HAM-D scores. Postrandomization expectancy scores were significantly higher in the open group (mean=12.1 [SD=2.1]) compared with the placebo-controlled group (mean=11.0 [SD=2.0]). Mixed-effects modeling revealed a significant week-by-group interaction, indicating that HAM-D scores for citalopram-treated participants declined at a faster rate in the open group compared with the placebo-controlled group. Patient expectations postrandomization partially mediated group effects on week 8 HAM-D. Patient expectancy is a significant mediator of placebo effects in antidepressant trials. Expectancy-related interventions should be investigated as a means of controlling placebo responses in antidepressant clinical trials and improving patient outcome in clinical treatment.

Posttraumatic Stress Disorder as a Mediator Between Trauma Exposure and Comorbid Mental Health Conditions in North Korean Refugee Youth Resettled in South Korea.

PubMed

Kim, Yeunhee J

2016-02-01

A structural equation model was used to investigate the relationship between trauma exposure and comorbid mental health problems and the mediation effect of posttraumatic stress disorder (PTSD) between trauma and mental health variables. The research model is based on the stress-vulnerability conceptual framework in which PTSD as a comorbid disorder mediates the relationship between trauma exposure and mental health problems. A self-administered survey was administered to 144 North Korean refugee youth residing in South Korea. Trauma exposure, both interpersonal and noninterpersonal, had no direct relationship with comorbid mental health problems. However, interpersonal trauma contributed to comorbid mental health problems through PTSD, demonstrating the mediation effect of PTSD and supporting the stress-vulnerability hypothesis of the current research model. Clinical implications of the study and future direction for research are discussed. © The Author(s) 2014.

Beyond total treatment effects in randomised controlled trials: Baseline measurement of intermediate outcomes needed to reduce confounding in mediation investigations.

PubMed

Landau, Sabine; Emsley, Richard; Dunn, Graham

2018-06-01

Random allocation avoids confounding bias when estimating the average treatment effect. For continuous outcomes measured at post-treatment as well as prior to randomisation (baseline), analyses based on (A) post-treatment outcome alone, (B) change scores over the treatment phase or (C) conditioning on baseline values (analysis of covariance) provide unbiased estimators of the average treatment effect. The decision to include baseline values of the clinical outcome in the analysis is based on precision arguments, with analysis of covariance known to be most precise. Investigators increasingly carry out explanatory analyses to decompose total treatment effects into components that are mediated by an intermediate continuous outcome and a non-mediated part. Traditional mediation analysis might be performed based on (A) post-treatment values of the intermediate and clinical outcomes alone, (B) respective change scores or (C) conditioning on baseline measures of both intermediate and clinical outcomes. Using causal diagrams and Monte Carlo simulation, we investigated the performance of the three competing mediation approaches. We considered a data generating model that included three possible confounding processes involving baseline variables: The first two processes modelled baseline measures of the clinical variable or the intermediate variable as common causes of post-treatment measures of these two variables. The third process allowed the two baseline variables themselves to be correlated due to past common causes. We compared the analysis models implied by the competing mediation approaches with this data generating model to hypothesise likely biases in estimators, and tested these in a simulation study. We applied the methods to a randomised trial of pragmatic rehabilitation in patients with chronic fatigue syndrome, which examined the role of limiting activities as a mediator. Estimates of causal mediation effects derived by approach (A) will be biased if one of the three processes involving baseline measures of intermediate or clinical outcomes is operating. Necessary assumptions for the change score approach (B) to provide unbiased estimates under either process include the independence of baseline measures and change scores of the intermediate variable. Finally, estimates provided by the analysis of covariance approach (C) were found to be unbiased under all the three processes considered here. When applied to the example, there was evidence of mediation under all methods but the estimate of the indirect effect depended on the approach used with the proportion mediated varying from 57% to 86%. Trialists planning mediation analyses should measure baseline values of putative mediators as well as of continuous clinical outcomes. An analysis of covariance approach is recommended to avoid potential biases due to confounding processes involving baseline measures of intermediate or clinical outcomes, and not simply for increased precision.

The Relationship between Authoritarian Leadership and Employees’ Deviant Workplace Behaviors: The Mediating Effects of Psychological Contract Violation and Organizational Cynicism

PubMed Central

Jiang, Hongyan; Chen, Yang; Sun, Peizhen; Yang, Jun

2017-01-01

This study investigated the relationship between authoritarian leadership and employees’ deviant workplace behaviors (DWB), as well as the mediating effects of psychological contract violation and organizational cynicism. A cross-sectional survey was conducted among 391 manufacturing workers in a northern city of China. Structural equation modeling was performed to test the theory-driven models. The results showed that the relationship between authoritarian leadership and employees’ DWB was mediated by organizational cynicism. Moreover, this relationship was also sequentially mediated by psychological contract violation and organizational cynicism. This research unveiled psychological contract violation and organizational cynicism as underlying mechanism that explained the link between authoritarian leadership and employees’ DWB. PMID:28536550

Processes of change in a school-based mindfulness programme: cognitive reactivity and self-coldness as mediators.

PubMed

Van der Gucht, Katleen; Takano, Keisuke; Raes, Filip; Kuppens, Peter

2018-05-01

The underlying mechanisms of the effectiveness of mindfulness-based interventions for emotional well-being remain poorly understood. Here, we examined the potential mediating effects of cognitive reactivity and self-compassion on symptoms of depression, anxiety and stress using data from an earlier randomised controlled school trial. A moderated time-lagged mediation model based on multilevel modelling was used to analyse the data. The findings showed that post-treatment changes in cognitive reactivity and self-coldness, an aspect of self-compassion, mediated subsequent changes in symptoms of depression, anxiety and stress. These results suggest that cognitive reactivity and self-coldness may be considered as transdiagnostic mechanisms of change of a mindfulness-based intervention programme for youth.

How Coaches' Motivations Mediate Between Basic Psychological Needs and Well-Being/Ill-Being.

PubMed

Alcaraz, Saul; Torregrosa, Miquel; Viladrich, Carme

2015-01-01

The purpose of the present research was to test how behavioral regulations are mediated between basic psychological needs and psychological well-being and ill-being in a sample of team-sport coaches. Based on self-determination theory, we hypothesized a model where satisfaction and thwarting of the basic psychological needs predicted coaches' behavioral regulations, which in turn led them to experience well-being (i.e., subjective vitality, positive affect) or ill-being (i.e., perceived stress, negative affect). Three-hundred and two coaches participated in the study (Mage = 25.97 years; 82% male). For each instrument employed, the measurement model with the best psychometric properties was selected from a sequence of nested models sustained by previous research, including exploratory structural equation models and confirmatory factor analysis. These measurement models were included in 3 structural equation models to test for mediation: partial mediation, complete mediation, and absence of mediation. The results provided support for the partial mediation model. Coaches' motivation mediated the relationships from both relatedness need satisfaction and basic psychological needs thwarting for coaches' well-being. In contrast, relationships between basic psychological needs satisfaction and thwarting and ill-being were only predicted by direct effects. Our results highlight that 3 conditions seem necessary for coaches to experience psychological well-being in their teams: basic psychological needs satisfaction, especially relatedness; lack of basic psychological needs thwarting; and self-determined motivation.

Demonstration and evaluation of a method for assessing mediated moderation.

PubMed

Morgan-Lopez, Antonio A; MacKinnon, David P

2006-02-01

Mediated moderation occurs when the interaction between two variables affects a mediator, which then affects a dependent variable. In this article, we describe the mediated moderation model and evaluate it with a statistical simulation using an adaptation of product-of-coefficients methods to assess mediation. We also demonstrate the use of this method with a substantive example from the adolescent tobacco literature. In the simulation, relative bias (RB) in point estimates and standard errors did not exceed problematic levels of +/- 10% although systematic variability in RB was accounted for by parameter size, sample size, and nonzero direct effects. Power to detect mediated moderation effects appears to be severely compromised under one particular combination of conditions: when the component variables that make up the interaction terms are correlated and partial mediated moderation exists. Implications for the estimation of mediated moderation effects in experimental and nonexperimental research are discussed.

Direct and Indirect Effects of Tofacitinib on Treatment Satisfaction in Patients with Ulcerative Colitis.

PubMed

Panés, Julian; Su, Chinyu; Bushmakin, Andrew G; Cappelleri, Joseph C; Healey, Paul

2016-11-01

This mediation modelling analysis evaluated direct and indirect effects of tofacitinib, an oral, small molecule Janus kinase inhibitor under investigation for ulcerative colitis, on patient treatment satisfaction. Data from an 8-week randomized Phase 2 trial [NCT00787202] in adults with moderate-to-severe, active ulcerative colitis receiving twice-daily tofacitinib 0.5-15mg [n=146] or placebo [n=48] were analysed in patient-reported [n=149] and clinician-reported [n=170] outcomes-based mediation models. Binary predictor variable: Treatment [pooled active treatment vs placebo]. Eventual dependent variable: Week 8 patient treatment satisfaction [measured on a five-point Likert scale]. Mediators of treatment effect on satisfaction: Week 8 Inflammatory Bowel Disease Questionnaire domains [Bowel Symptoms, Emotional Health, Social Function and Systemic Symptoms] and Mayo scale domains [Stool Frequency, Rectal Bleeding, Physician's Global Assessment and Endoscopic Disease Activity] for patient-reported and clinician-reported models, respectively. Overall tofacitinib indirect effect on satisfaction via Inflammatory Bowel Disease Questionnaire domains was 40.5% [p<0.05] and via Mayo scale domains was 84.0% [p<0.01] for patient-reported and clinician-reported models, respectively. Bowel function had the most important indirect effect: of the total tofacitinib effect on satisfaction, 32.4% [p=0.05] was indirectly mediated via Bowel Symptoms; and 30.0% [p=0.04] via Stool Frequency. In total, 59.5% [p<0.01] and only 16.0% [p=0.56] of tofacitinib's effect on satisfaction was unrelated to Inflammatory Bowel Disease Questionnaire and Mayo scale domains in the patient-reported and clinician-reported models, respectively. Bowel function is an important factor for patient treatment satisfaction with tofacitinib. Treatment effect on patient satisfaction was almost completely mediated via improvement in Mayo scale domains. Copyright © 2016 European Crohn’s and Colitis Organisation (ECCO). Published by Oxford University Press. All rights reserved. For permissions, please email: journals.permissions@oup.com.

Marital Aggression and Child Peer Competence: A Comparison of Three Conceptual Models

PubMed Central

Finger, Brent; Eiden, Rina D.; Edwards, Ellen P.; Leonard, Kenneth E.; Kachadourian, Lorig

2013-01-01

This study examined longitudinal data linking marital aggression with child peer competence in kindergarten. The study compared three conceptual models for understanding the relation between marital aggression and child peer competence. Model 1 examines the direct effects of marital aggression, parental alcoholism, and parenting on child peer competence, model 2 posits that this relation is mediated by child social problem solving abilities (social information processing theory), while model 3 proposes that the relation is mediated by parental warmth/sensitivity (spillover theory). Structural Equation Modeling was most supportive of models 1 and 3 indicating that parenting behavior, but not social problem solving, partially mediates the relation between marital conflict and child peer competence. PMID:24009468

Public reaction to Chikungunya outbreaks in Italy-Insights from an extensive novel data streams-based structural equation modeling analysis.

PubMed

Mahroum, Naim; Adawi, Mohammad; Sharif, Kassem; Waknin, Roy; Mahagna, Hussein; Bisharat, Bishara; Mahamid, Mahmud; Abu-Much, Arsalan; Amital, Howard; Luigi Bragazzi, Nicola; Watad, Abdulla

2018-01-01

The recent outbreak of Chikungunya virus in Italy represents a serious public health concern, which is attracting media coverage and generating public interest in terms of Internet searches and social media interactions. Here, we sought to assess the Chikungunya-related digital behavior and the interplay between epidemiological figures and novel data streams traffic. Reaction to the recent outbreak was analyzed in terms of Google Trends, Google News and Twitter traffic, Wikipedia visits and edits, and PubMed articles, exploiting structural modelling equations. A total of 233,678 page-views and 150 edits on the Italian Wikipedia page, 3,702 tweets, 149 scholarly articles, and 3,073 news articles were retrieved. The relationship between overall Chikungunya cases, as well as autochthonous cases, and tweets production was found to be fully mediated by Chikungunya-related web searches. However, in the allochthonous/imported cases model, tweet production was not found to be significantly mediated by epidemiological figures, with web searches still significantly mediating tweet production. Inconsistent relationships were detected in mediation models involving Wikipedia usage as a mediator variable. Similarly, the effect between news consumption and tweets production was suppressed by the Wikipedia usage. A further inconsistent mediation was found in the case of the effect between Wikipedia usage and tweets production, with web searches as a mediator variable. When adjusting for the Internet penetration index, similar findings could be obtained, with the important exception that in the adjusted model the relationship between GN and Twitter was found to be partially mediated by Wikipedia usage. Furthermore, the link between Wikipedia usage and PubMed/MEDLINE was fully mediated by GN, differently from what was found in the unadjusted model. In conclusion-a significant public reaction to the current Chikungunya outbreak was documented. Health authorities should be aware of this, recognizing the role of new technologies for collecting public concerns and replying to them, disseminating awareness and avoid misleading information.

Public reaction to Chikungunya outbreaks in Italy—Insights from an extensive novel data streams-based structural equation modeling analysis

PubMed Central

Sharif, Kassem; Waknin, Roy; Mahagna, Hussein; Bisharat, Bishara; Mahamid, Mahmud; Abu-Much, Arsalan; Amital, Howard; Luigi Bragazzi, Nicola

2018-01-01

The recent outbreak of Chikungunya virus in Italy represents a serious public health concern, which is attracting media coverage and generating public interest in terms of Internet searches and social media interactions. Here, we sought to assess the Chikungunya-related digital behavior and the interplay between epidemiological figures and novel data streams traffic. Reaction to the recent outbreak was analyzed in terms of Google Trends, Google News and Twitter traffic, Wikipedia visits and edits, and PubMed articles, exploiting structural modelling equations. A total of 233,678 page-views and 150 edits on the Italian Wikipedia page, 3,702 tweets, 149 scholarly articles, and 3,073 news articles were retrieved. The relationship between overall Chikungunya cases, as well as autochthonous cases, and tweets production was found to be fully mediated by Chikungunya-related web searches. However, in the allochthonous/imported cases model, tweet production was not found to be significantly mediated by epidemiological figures, with web searches still significantly mediating tweet production. Inconsistent relationships were detected in mediation models involving Wikipedia usage as a mediator variable. Similarly, the effect between news consumption and tweets production was suppressed by the Wikipedia usage. A further inconsistent mediation was found in the case of the effect between Wikipedia usage and tweets production, with web searches as a mediator variable. When adjusting for the Internet penetration index, similar findings could be obtained, with the important exception that in the adjusted model the relationship between GN and Twitter was found to be partially mediated by Wikipedia usage. Furthermore, the link between Wikipedia usage and PubMed/MEDLINE was fully mediated by GN, differently from what was found in the unadjusted model. In conclusion—a significant public reaction to the current Chikungunya outbreak was documented. Health authorities should be aware of this, recognizing the role of new technologies for collecting public concerns and replying to them, disseminating awareness and avoid misleading information. PMID:29795578

Investigating the effect of child maltreatment on early adolescent peer-on-peer sexual aggression: testing a multiple mediator model in a non-incarcerated sample of Danish adolescents.

PubMed

Bramsen, Rikke Holm; Lasgaard, Mathias; Koss, Mary P; Elklit, Ask; Banner, Jytte

2014-01-01

The aim of the present study was to investigate the relationship between child maltreatment and severe early adolescent peer-on-peer sexual aggression, using a multiple mediator model. The study comprised 330 male Grade 9 students with a mean age of 14.9 years (SD=0.5). Estimates from the mediation model indicated significant indirect effects of child physical abuse on sexual aggression via peer influence and insecure-hostile masculinity. No significant total effect of child sexual abuse and child neglect on sexual aggression was found. Findings of the present study identify risk factors that are potentially changeable and therefore of value in informing the design of prevention programs aiming at early adolescent peer-on-peer sexual aggression in at-risk youth.

Working memory and intraindividual variability as neurocognitive indicators in ADHD: examining competing model predictions.

PubMed

Kofler, Michael J; Alderson, R Matt; Raiker, Joseph S; Bolden, Jennifer; Sarver, Dustin E; Rapport, Mark D

2014-05-01

The current study examined competing predictions of the default mode, cognitive neuroenergetic, and functional working memory models of attention-deficit/hyperactivity disorder (ADHD) regarding the relation between neurocognitive impairments in working memory and intraindividual variability. Twenty-two children with ADHD and 15 typically developing children were assessed on multiple tasks measuring intraindividual reaction time (RT) variability (ex-Gaussian: tau, sigma) and central executive (CE) working memory. Latent factor scores based on multiple, counterbalanced tasks were created for each construct of interest (CE, tau, sigma) to reflect reliable variance associated with each construct and remove task-specific, test-retest, and random error. Bias-corrected, bootstrapped mediation analyses revealed that CE working memory accounted for 88% to 100% of ADHD-related RT variability across models, and between-group differences in RT variability were no longer detectable after accounting for the mediating role of CE working memory. In contrast, RT variability accounted for 10% to 29% of between-group differences in CE working memory, and large magnitude CE working memory deficits remained after accounting for this partial mediation. Statistical comparison of effect size estimates across models suggests directionality of effects, such that the mediation effects of CE working memory on RT variability were significantly greater than the mediation effects of RT variability on CE working memory. The current findings question the role of RT variability as a primary neurocognitive indicator in ADHD and suggest that ADHD-related RT variability may be secondary to underlying deficits in CE working memory.

Psychological distress longitudinally mediates the effect of vertigo symptoms on vertigo-related handicap.

PubMed

Probst, Thomas; Dinkel, Andreas; Schmid-Mühlbauer, Gabriele; Radziej, Katharina; Limburg, Karina; Pieh, Christoph; Lahmann, Claas

2017-02-01

Vertigo symptoms can lead to more or less vertigo-related handicap. This longitudinal study investigated whether depression, anxiety, and/or somatization mediate the relationship between vertigo symptoms and vertigo-related handicap. N=111 patients with vertigo/dizziness provided complete data on the following measures: Vertigo symptoms at baseline, depression at 6-month follow-up, anxiety at 6-month follow-up, somatization at 6-month follow-up, and vertigo handicap at 12-month follow-up. Mediation analyses with bootstrapping were performed to investigate the mediating role of anxiety, depression, and somatization in the relationship between vertigo symptoms and vertigo-related handicap. When the mediating role of anxiety, depression, and somatization was evaluated separately from each other in single mediation models, the effect vertigo symptoms at baseline exerted on vertigo-related handicap at 12-month follow-up was significantly mediated by depression at 6-month follow-up (p<0.05), by anxiety at 6-month follow-up (p<0.05), as well as by somatization at 6-month follow-up (p<0.05). When statistically controlling for the other mediators in a multiple mediator model, only depression at 6-month follow-up mediated the effect of vertigo symptoms at baseline on vertigo-related handicap at 12-month follow-up (p<0.05). Psychological distress is an important mechanism in the process how vertigo symptoms lead to vertigo-related handicap. Copyright © 2016 Elsevier Inc. All rights reserved.

Neighborhood Social Cohesion as a Mediator of Neighborhood Conditions on Mothers' Engagement in Physical Activity: Results From the Geographic Research on Wellbeing Study.

PubMed

Yuma-Guerrero, Paula J; Cubbin, Catherine; von Sternberg, Kirk

2017-12-01

The purpose of this study was to determine if social cohesion mediates the effects of neighborhood and household-level socioeconomic status (SES), perceptions of neighborhood safety, and access to parks on mothers' engagement in physical activity (PA). Secondary analyses were conducted on cross-sectional data from The Geographic Research on Wellbeing (GROW) study. GROW includes survey data from a diverse sample of 2,750 California mothers. Structural equation modeling was used to test a conceptual multilevel mediation model, proposing social cohesion as a mediator of known predictors of PA. Social cohesion fully mediated the pathway from perceived neighborhood safety to mothers' PA. Social cohesion also mediated the significant relationship between neighborhood SES and PA; however, this mediation finding was not practically significant when considered in the context of the full model. Household SES was significantly positively related to both social cohesion and PA. Park access contributed significantly to social cohesion but not directly to PA Social cohesion did not significantly mediate relationships between park access or household SES and PA. There is a need for public health interventions to improve engagement in PA among individuals and neighborhoods with lower levels of socioeconomic resources. Interventions that create social cohesion within neighborhoods may have positive effects on mothers' PA, particularly in neighborhoods perceived as unsafe.

Does Anger Regulation Mediate the Discrimination-Mental Health Link among Mexican-Origin Adolescents? A Longitudinal Mediation Analysis Using Multilevel Modeling

PubMed Central

Park, Irene J. K.; Wang, Lijuan; Williams, David R.; Alegría, Margarita

2016-01-01

Although prior research has consistently documented the association between racial/ethnic discrimination and poor mental health outcomes, the mechanisms that underlie this link are still unclear. The present three-wave longitudinal study tested the mediating role of anger regulation in the discrimination—mental health link among 269 Mexican-origin adolescents (Mage = 14.1 years, SD = 1.6; 57% girls), 12 – 17 years old. Three competing anger regulation variables were tested as potential mediators: outward anger expression, anger suppression, and anger control. Longitudinal mediation analyses were conducted using multilevel modeling that disaggregated within-person effects from between-person effects. Results indicated that outward anger expression was a significant mediator; anger suppression and anger control were not significant mediators. Within a given individual, greater racial/ethnic discrimination was associated with more frequent outward anger expression. In turn, more frequent outward anger expression was associated with higher levels of anxiety and depression at a given time point. Gender, age, and nativity status were not significant moderators of the hypothesized mediation models. By identifying outward anger expression as an explanatory mechanism in the discrimination-distress link among Latino youths, this study points to a malleable target for prevention and intervention efforts aimed at mitigating the detrimental impact of racism on Latino youths’ mental health during the developmentally critical period of adolescence. PMID:27893238

Investigating Transporter‐Mediated Drug‐Drug Interactions Using a Physiologically Based Pharmacokinetic Model of Rosuvastatin

PubMed Central

Wang, Q; Leil, T

2017-01-01

Rosuvastatin is a frequently used probe in transporter‐mediated drug‐drug interaction (DDI) studies. This report describes the development of a physiologically based pharmacokinetic (PBPK) model of rosuvastatin for prediction of pharmacokinetic (PK) DDIs. The rosuvastatin model predicted the observed single (i.v. and oral) and multiple dose PK profiles, as well as the impact of coadministration with transporter inhibitors. The predicted effects of rifampin and cyclosporine (6.58‐fold and 5.07‐fold increase in rosuvastatin area under the curve (AUC), respectively) were mediated primarily via inhibition of hepatic organic anion‐transporting polypeptide (OATP)1B1 (Inhibition constant (Ki) ∼1.1 and 0.014 µM, respectively) and OATP1B3 (Ki ∼0.3 and 0.007 µM, respectively), with cyclosporine also inhibiting intestinal breast cancer resistance protein (BCRP; Ki ∼0.07 µM). The predicted effects of gemfibrozil and its metabolite were moderate (1.88‐fold increase in rosuvastatin AUC) and mediated primarily via inhibition of hepatic OATP1B1 and renal organic cation transporter 3. This model of rosuvastatin will be useful in prospectively predicting transporter‐mediated DDIs with novel pharmaceutical agents in development. PMID:28296193

Does positivity mediate the relation of extraversion and neuroticism with subjective happiness?

PubMed

Lauriola, Marco; Iani, Luca

2015-01-01

Recent theories suggest an important role of neuroticism, extraversion, attitudes, and global positive orientations as predictors of subjective happiness. We examined whether positivity mediates the hypothesized relations in a community sample of 504 adults between the ages of 20 and 60 years old (females = 50%). A model with significant paths from neuroticism to subjective happiness, from extraversion and neuroticism to positivity, and from positivity to subjective happiness fitted the data (Satorra-Bentler scaled chi-square (38) = 105.91; Comparative Fit Index = .96; Non-Normed Fit Index = .95; Root Mean Square Error of Approximation = .060; 90% confidence interval = .046, .073). The percentage of subjective happiness variance accounted for by personality traits was only about 48%, whereas adding positivity as a mediating factor increased the explained amount of subjective happiness to 78%. The mediation model was invariant by age and gender. The results show that the effect of extraversion on happiness was fully mediated by positivity, whereas the effect of neuroticism was only partially mediated. Implications for happiness studies are also discussed.

Mediating role of critical thinking disposition in the relationship between perceived barriers to research use and evidence-based practice.

PubMed

Kim, Sun-Ae; Song, Youngshin; Sim, Hee-Sook; Ahn, Eun-Kyong; Kim, Jung-Hee

2015-01-01

Despite the importance of critical thinking in clinical and educational settings, little is known about its role in evidence-based practice (EBP). This study examined whether critical thinking disposition (CTD) mediates the relationship between perceived barriers to research use and EBP in clinical nurses (N=409). A path diagram using structural equation modeling was used to estimate the direct and indirect effects of perceived barriers to research use on EBP, controlling for CTD as a mediator. CTD partially mediated the relationship between perceived barriers to research use and EBP. Furthermore, the hypothesized mediation model demonstrated an appropriate fit to the data. Individual and organizational efforts are needed to help nurses further improve their critical thinking skills. CTD is important as research barriers to engage effectively in EBP. Without the skills to evaluate evidence carefully, research utilization may be compromised.

Impact of Study Skills and Parent Education on First-Year GPA Among College Students With and Without ADHD: A Moderated Mediation Model.

PubMed

Gormley, Matthew J; Pinho, Trevor; Pollack, Brittany; Puzino, Kristina; Franklin, Melanie K; Busch, Chelsea; DuPaul, George J; Weyandt, Lisa L; Anastopoulos, Arthur D

2018-02-01

To test if the relationship between ADHD and academic achievement is mediated by service utilization and/or study skills, and if these mediation effects are moderated by parental education level. A bootstrapping method within structural equation modeling was used with data from 355 first year college students meeting strict criteria for ADHD or clearly without ADHD to test the mediation and moderation effects. Study skills, but not service utilization, significantly mediated the relationship between ADHD status and GPA; however, this relationship was not significant among students with at least one parent holding a master's degree or higher. Among first year college students study skills may be a more salient predictor of educational outcomes relative to ADHD status. Additional research into support services for college students with ADHD is needed, however, results suggest interventions targeting study skills may hold particular promise for these students.

Self-reported impulsivity, but not behavioral choice or response impulsivity, partially mediates the effect of stress on drinking behavior

PubMed Central

HAMILTON, KRISTEN R.; ANSELL, EMILY B.; REYNOLDS, BRADY; POTENZA, MARC N.; SINHA, RAJITA

2013-01-01

Stress and impulsivity contribute to alcohol use, and stress may also act via impulsivity to increase drinking behavior. Impulsivity represents a multi-faceted construct and self-report and behavioral assessments may effectively capture distinct clinically relevant factors. The present research investigated whether aspects of impulsivity mediate the effect of stress on alcohol use. A community-based sample of 192 men and women was assessed on measures of cumulative stress, alcohol use, self-reported impulsivity, and behavioral choice and response impulsivity. Data were analyzed using regression and bootstrapping techniques to estimate indirect effects of stress on drinking via impulsivity. Cumulative adversity exhibited both direct effects and indirect effects (via self-reported impulsivity) on drinking behavior. Additional models examining specific types of stress indicated direct and indirect effects of trauma and recent life events, and indirect effects of major life events and chronic stressors on drinking behavior. Overall, cumulative stress was associated with increased drinking behavior, and this effect was partially mediated by self-reported impulsivity. Self-reported impulsivity also mediated the effects of different types of stress on drinking behavior. These findings highlight the value of mediation models to examine the pathways through which different types of stress increase drinking behavior. Treatment and prevention strategies should focus on enhancing stress management and self-control. PMID:22376044

Self-reported impulsivity, but not behavioral choice or response impulsivity, partially mediates the effect of stress on drinking behavior.

PubMed

Hamilton, Kristen R; Ansell, Emily B; Reynolds, Brady; Potenza, Marc N; Sinha, Rajita

2013-01-01

Stress and impulsivity contribute to alcohol use, and stress may also act via impulsivity to increase drinking behavior. Impulsivity represents a multi-faceted construct and self-report and behavioral assessments may effectively capture distinct clinically relevant factors. The present research investigated whether aspects of impulsivity mediate the effect of stress on alcohol use. A community-based sample of 192 men and women was assessed on measures of cumulative stress, alcohol use, self-reported impulsivity, and behavioral choice and response impulsivity. Data were analyzed using regression and bootstrapping techniques to estimate indirect effects of stress on drinking via impulsivity. Cumulative adversity exhibited both direct effects and indirect effects (via self-reported impulsivity) on drinking behavior. Additional models examining specific types of stress indicated direct and indirect effects of trauma and recent life events, and indirect effects of major life events and chronic stressors on drinking behavior. Overall, cumulative stress was associated with increased drinking behavior, and this effect was partially mediated by self-reported impulsivity. Self-reported impulsivity also mediated the effects of different types of stress on drinking behavior. These findings highlight the value of mediation models to examine the pathways through which different types of stress increase drinking behavior. Treatment and prevention strategies should focus on enhancing stress management and self-control.

The relationship between childhood trauma and the severity of adulthood depression and anxiety symptoms in a clinical sample: The mediating role of cognitive emotion regulation strategies.

PubMed

Huh, Hyu Jung; Kim, Kyung Hee; Lee, Hee-Kyung; Chae, Jeong-Ho

2017-04-15

Childhood trauma is an important factor in adverse mental health outcomes, including depression and anxiety. The purpose of the present study was to evaluate a hypothesized model describing a pathway of childhood trauma and its influence on psychiatric symptoms in patients with depressive disorder. In this model, childhood trauma was positively associated with current depression and anxiety symptoms, which were mediated by a cognitive emotional regulation strategy. Patients with depressive disorder (n=585, 266 men, 316 women) completed the Beck Depression Inventory (BDI), State-Trait Anxiety Inventory (STAI), Childhood Trauma Questionnaire (CTQ), and Cognitive Emotion Regulation Questionnaire (CERQ). We divided the cognitive emotion regulation strategies into adaptive and maladaptive strategies using a CERQ subscore. We employed structural equation modeling (SEM) and simple/multiple mediation analyses. The indirect effect of maladaptive strategies was significant in the relationship between overall childhood trauma and depression/anxiety severity, whereas the mediation effect of adaptive strategies was limited to depressive symptoms. With respect to specific types of trauma, maladaptive strategies mediated the association between emotional abuse and current depression/anxiety, while the mediation effect of adaptive strategies was limited to emotional neglect. This study's cross-sectional design does not allow establishment of causal relationships. Childhood trauma recall bias may be possible. These findings support the hypothesized model in which childhood trauma is associated with adulthood depression/anxiety symptoms in clinical samples, and mediated by emotion regulation strategies. These results suggest that cognitive emotion dysregulation is an important factor affecting depression/anxiety symptoms in patients with childhood trauma. Copyright © 2017 Elsevier B.V. All rights reserved.

Information processing versus social cognitive mediators of weight loss in a podcast-delivered health intervention.

PubMed

Ko, Linda K; Turner-McGrievy, Gabrielle M; Campbell, Marci K

2014-04-01

Podcasting is an emerging technology, and previous interventions have shown promising results using theory-based podcast for weight loss among overweight and obese individuals. This study investigated whether constructs of social cognitive theory and information processing theories (IPTs) mediate the effect of a podcast intervention on weight loss among overweight individuals. Data are from Pounds off Digitally, a study testing the efficacy of two weight loss podcast interventions (control podcast and theory-based podcast). Path models were constructed (n = 66). The IPTs, elaboration likelihood model, information control theory, and cognitive load theory mediated the effect of a theory-based podcast on weight loss. The intervention was significantly associated with all IPTs. Information control theory and cognitive load theory were related to elaboration, and elaboration was associated with weight loss. Social cognitive theory constructs did not mediate weight loss. Future podcast interventions grounded in theory may be effective in promoting weight loss.

Help seeking in aggressive and nonaggressive boys as a function of social or mechanical mediation of assistance.

PubMed

Shea, B J; Routh, D K; Cottrell, N B; Brecht, J M

1973-04-01

The behavior of preadolescent and adolescent boys, rated as aggressive and nonaggressive, was examined to test predictions from Bandura and Walters' social-learning theory and from Weiss and Miller's punishment model of audience-observation effects. The subjects were given a bogus motor task, actually insoluble, with help available on each trial. For half the subjects, help was given through the mediation of a social agent; for the rest, help was on a nonsocial, mechanically mediated basis. The groups for whom help was socially mediated made fewer help-seeking responses and decreased the number of such responses over successive trial blocks. The predictions from Bandura and Walters' theory were not supported, since neither age nor degree of aggressiveness had an effect on help-seeking responses. The results were, however, consistent with the punishment model of audience effects.

Divergent pathways to influence: Cognition and behavior differentially mediate the effects of optimism on physical and mental quality of life in Chinese university students.

PubMed

Ramsay, Jonathan E; Yang, Fang; Pang, Joyce S; Lai, Ching-Man; Ho, Roger Cm; Mak, Kwok-Kei

2015-07-01

Previous research has indicated that both cognitive and behavioral variables mediate the positive effect of optimism on quality of life; yet few attempts have been made to accommodate these constructs into a single explanatory framework. Adopting Fredrickson's broaden-and-build perspective, we examined the relationships between optimism, self-rated health, resilience, exercise, and quality of life in 365 Chinese university students using path analysis. For physical quality of life, a two-stage model, in which the effects of optimism were sequentially mediated by cognitive and behavioral variables, provided the best fit. A one-stage model, with full mediation by cognitive variables, provided the best fit for mental quality of life. This suggests that optimism influences physical and mental quality of life via different pathways. © The Author(s) 2013.

Religion, Purpose in Life, Social Support, and Psychological Distress in Chinese University Students.

PubMed

Wang, Zhizhong; Koenig, Harold G; Ma, Hui; Shohaib, Saad Al

2016-06-01

We examined the relationship between religious involvement and psychological distress and explored the mediating effects of social support and purpose in life in university students in western, mid-western, and eastern China. Cross-sectional survey of a representative sample of 1812 university students was conducted. The Purpose in Life scale, Duke Social Support Index, and Religious Commitment Inventory-10 were administered, along with Kessler's Psychological Distress Scale. Structural equation modeling was used to test two models of the mediation hypothesis, examining direct, indirect, and total effects. Model 1 (with direction of effect hypothesized from religiosity to psychological distress) indicated that religious involvement had a direct effect on increasing psychological distress (β = 0.23, p < .01) with minor mediated effects. However, Model 2 (with direction of effect hypothesized from psychological distress to religiosity) indicated strong indirect protective effects of religiosity on psychological distress through purpose in life and social support (β = -.40, p < .01). The findings are consistent with the hypothesis that psychological distress increases religious involvement, which then increases purpose in life and social support that then lead to lower psychological distress.

What factors mediate the relationship between global self-worth and weight and shape concerns?

PubMed

Murphy, Edel; Dooley, Barbara; Menton, Aoife; Dolphin, Louise

2016-04-01

The primary aim of this study was to investigate whether the relationship between global self-worth and weight concerns and global self-worth and shape concerns was mediated by pertinent body image factors, while controlling for gender and estimated BMI. Participants were 775 adolescents (56% male) aged 12-18years (M=14.6; SD=1.50). Mediation analysis revealed a direct and a mediated effect between global self-worth and two body image models: 1) weight concerns and 2) shape concerns. The strongest mediators in both models were physical appearance, restrained eating, and depression. Partial mediation was observed for both models, indicating that body image factors which span cognitive, affective, and behavioral constructs, explain the association between global self-worth and weight and shape concerns. Implications for future research, weight and shape concern prevention and global self-worth enhancement programs are discussed. Copyright © 2016 Elsevier Ltd. All rights reserved.

Fitness, Sleep-Disordered Breathing, Symptoms of Depression, and Cognition in Inactive Overweight Children: Mediation Models.

PubMed

Stojek, Monika M K; Montoya, Amanda K; Drescher, Christopher F; Newberry, Andrew; Sultan, Zain; Williams, Celestine F; Pollock, Norman K; Davis, Catherine L

We used mediation models to examine the mechanisms underlying the relationships among physical fitness, sleep-disordered breathing (SDB), symptoms of depression, and cognitive functioning. We conducted a cross-sectional secondary analysis of the cohorts involved in the 2003-2006 project PLAY (a trial of the effects of aerobic exercise on health and cognition) and the 2008-2011 SMART study (a trial of the effects of exercise on cognition). A total of 397 inactive overweight children aged 7-11 received a fitness test, standardized cognitive test (Cognitive Assessment System, yielding Planning, Attention, Simultaneous, Successive, and Full Scale scores), and depression questionnaire. Parents completed a Pediatric Sleep Questionnaire. We used bootstrapped mediation analyses to test whether SDB mediated the relationship between fitness and depression and whether SDB and depression mediated the relationship between fitness and cognition. Fitness was negatively associated with depression ( B = -0.041; 95% CI, -0.06 to -0.02) and SDB ( B = -0.005; 95% CI, -0.01 to -0.001). SDB was positively associated with depression ( B = 0.99; 95% CI, 0.32 to 1.67) after controlling for fitness. The relationship between fitness and depression was mediated by SDB (indirect effect = -0.005; 95% CI, -0.01 to -0.0004). The relationship between fitness and the attention component of cognition was independently mediated by SDB (indirect effect = 0.058; 95% CI, 0.004 to 0.13) and depression (indirect effect = -0.071; 95% CI, -0.01 to -0.17). SDB mediates the relationship between fitness and depression, and SDB and depression separately mediate the relationship between fitness and the attention component of cognition.

Modeling the Interplay Between Psychological Processes and Adverse, Stressful Contexts and Experiences in Pathways to Psychosis: An Experience Sampling Study

PubMed Central

Klippel, Annelie; Myin-Germeys, Inez; Chavez-Baldini, UnYoung; Preacher, Kristopher J.; Kempton, Matthew; Valmaggia, Lucia; Calem, Maria; So, Suzanne; Beards, Stephanie; Hubbard, Kathryn; Gayer-Anderson, Charlotte; Onyejiaka, Adanna; Wichers, Marieke; McGuire, Philip; Murray, Robin; Garety, Philippa; van Os, Jim; Wykes, Til; Morgan, Craig

2017-01-01

Abstract Several integrated models of psychosis have implicated adverse, stressful contexts and experiences, and affective and cognitive processes in the onset of psychosis. In these models, the effects of stress are posited to contribute to the development of psychotic experiences via pathways through affective disturbance, cognitive biases, and anomalous experiences. However, attempts to systematically test comprehensive models of these pathways remain sparse. Using the Experience Sampling Method in 51 individuals with first-episode psychosis (FEP), 46 individuals with an at-risk mental state (ARMS) for psychosis, and 53 controls, we investigated how stress, enhanced threat anticipation, and experiences of aberrant salience combine to increase the intensity of psychotic experiences. We fitted multilevel moderated mediation models to investigate indirect effects across these groups. We found that the effects of stress on psychotic experiences were mediated via pathways through affective disturbance in all 3 groups. The effect of stress on psychotic experiences was mediated by threat anticipation in FEP individuals and controls but not in ARMS individuals. There was only weak evidence of mediation via aberrant salience. However, aberrant salience retained a substantial direct effect on psychotic experiences, independently of stress, in all 3 groups. Our findings provide novel insights on the role of affective disturbance and threat anticipation in pathways through which stress impacts on the formation of psychotic experiences across different stages of early psychosis in daily life. PMID:28204708

You can hide but you have to run: Direct detection with vector mediators

DOE PAGES

D’Eramo, Francesco; Kavanagh, Bradley J.; Panci, Paolo

2016-08-18

We study direct detection in simplified models of Dark Matter (DM) in which interactions with Standard Model (SM) fermions are mediated by a heavy vector boson. We consider fully general, gauge-invariant couplings between the SM, the mediator and both scalar and fermion DM. We account for the evolution of the couplings between the energy scale of the mediator mass and the nuclear energy scale. This running arises from virtual effects of SM particles and its inclusion is not optional. We compare bounds on the mediator mass from direct detection experiments with and without accounting for the running. In some casesmore » the inclusion of these effects changes the bounds by several orders of magnitude, as a consequence of operator mixing which generates new interactions at low energy. We also highlight the importance of these effects when translating LHC limits on the mediator mass into bounds on the direct detection cross section. For an axial-vector mediator, the running can alter the derived bounds on the spin-dependent DM-nucleon cross section by a factor of two or more. Lastly, we provide tools to facilitate the inclusion of these effects in future studies: general approximate expressions for the low energy couplings and a public code runDM to evolve the couplings between arbitrary energy scales.« less

You can hide but you have to run: Direct detection with vector mediators

DOE Office of Scientific and Technical Information (OSTI.GOV)

D’Eramo, Francesco; Kavanagh, Bradley J.; Panci, Paolo

We study direct detection in simplified models of Dark Matter (DM) in which interactions with Standard Model (SM) fermions are mediated by a heavy vector boson. We consider fully general, gauge-invariant couplings between the SM, the mediator and both scalar and fermion DM. We account for the evolution of the couplings between the energy scale of the mediator mass and the nuclear energy scale. This running arises from virtual effects of SM particles and its inclusion is not optional. We compare bounds on the mediator mass from direct detection experiments with and without accounting for the running. In some casesmore » the inclusion of these effects changes the bounds by several orders of magnitude, as a consequence of operator mixing which generates new interactions at low energy. We also highlight the importance of these effects when translating LHC limits on the mediator mass into bounds on the direct detection cross section. For an axial-vector mediator, the running can alter the derived bounds on the spin-dependent DM-nucleon cross section by a factor of two or more. Lastly, we provide tools to facilitate the inclusion of these effects in future studies: general approximate expressions for the low energy couplings and a public code runDM to evolve the couplings between arbitrary energy scales.« less

Coping mediates the relationship between sense of coherence and mental quality of life in patients with chronic illness: a cross-sectional study.

PubMed

Kristofferzon, Marja-Leena; Engström, Maria; Nilsson, Annika

2018-07-01

The aim of the present study was to investigate relationships between sense of coherence, emotion-focused coping, problem-focused coping, coping efficiency, and mental quality of life (QoL) in patients with chronic illness. A model based on Lazarus' and Folkman's stress and coping theory tested the specific hypothesis: Sense of coherence has a direct and indirect effect on mental QoL mediated by emotion-focused coping, problem-focused coping, and coping efficiency in serial adjusted for age, gender, educational level, comorbidity, and economic status. The study used a cross-sectional and correlational design. Patients (n = 292) with chronic diseases (chronic heart failure, end-stage renal disease, multiple sclerosis, stroke, and Parkinson) completed three questionnaires and provided background data. Data were collected in 2012, and a serial multiple mediator model was tested using PROCESS macro for SPSS. The test of the conceptual model confirmed the hypothesis. There was a significant direct and indirect effect of sense of coherence on mental QoL through the three mediators. The model explained 39% of the variance in mental QoL. Self-perceived effective coping strategies are the most important mediating factors between sense of coherence and QoL in patients with chronic illness, which supports Lazarus' and Folkman's stress and coping theory.

Impact of emotional competence on supportive care needs, anxiety and depression symptoms of cancer patients: a multiple mediation model.

PubMed

Baudry, A-S; Lelorain, S; Mahieuxe, M; Christophe, V

2018-01-01

The aim of this study was to test the effect of intrapersonal and interpersonal emotional competence on cancer patients' supportive care needs, as mediated by anxiety and depression symptoms. Cross-sectional design: 137 cancer patients (42% breast or ovarian cancer, 58% gastrointestinal cancer) in 4 French hospitals completed the Profile of Emotional Competence (PEC), the Hospital Anxiety and Depression Scale (HADS), and the Supportive Care Needs Survey Short Form (SCNS-SF). Bootstrap methods with PROCESS Macro were used to test multiple mediation models. Emotional competence presented a direct or indirect beneficial effect on the satisfaction of supportive care needs, anxiety and depression symptoms. As expected, anxiety and depression symptoms had also strong positive correlations with unmet needs. All multiple mediation models were significant, except for physical needs: intrapersonal and interpersonal emotional competence impacted anxiety and depression symptoms, which in turn impacted psychological, sexual, care/support, and information needs. These innovative results show the important effect of patients' emotional competence on their supportive care need satisfaction, as mediated by anxiety and depression. Consequently, patients with high emotional competence may require less psychosocial input from medical clinicians. Thus, emotional competence may be integrated into health models and psychosocial interventions to improve patient adjustment. Further investigation is, however, needed to know which are the most beneficial specific emotional competences and at what point of the cancer pathway.

Social modeling of eating mediated by mirror neuron activity: A causal model moderated by frontal asymmetry and BMI.

PubMed

McGeown, Laura; Davis, Ron

2018-02-15

The social modeling of eating effect refers to the consistently demonstrated phenomenon that individuals tend to match their quantity of food intake to their eating companion. The current study sought to explore whether activity within the mirror neuron system (MNS) mediates the social modeling of eating effect as a function of EEG frontal asymmetry and body mass index (BMI). Under the guise of rating empathy, 93 female undergraduates viewed a female video confederate "incidentally" consume either a low or high intake of chips while electroencephalogram (EEG) activity was recorded. Subsequent ad libitum chip consumption was quantified. A first- and second-stage dual moderation model revealed that frontal asymmetry and BMI moderated an indirect effect of model consumption on participants' food consumption as mediated by MNS activity at electrode site C3, a 3 b 3 =-0.718, SE=0.365, 95% CI [-1.632, -0.161]. Left frontal asymmetry was associated with greater mu activity and a positive association between model and participant chip consumption, while right frontal asymmetry was associated with less mu activity and a negative association between model and participant consumption. Across all levels of frontal asymmetry, the effect was only significant among those with a BMI at the 50th percentile or lower. Thus, among leaner individuals, the MNS was demonstrated to mediate social modeling of eating, as moderated by frontal asymmetry. These findings are integrated within the normative account of social modeling of eating. It is proposed that the normative framework may benefit from consideration of both conscious and unconscious operation of intake norms. Copyright © 2017 Elsevier B.V. All rights reserved.

Causal mediation analysis with a binary outcome and multiple continuous or ordinal mediators: Simulations and application to an alcohol intervention.

PubMed

Nguyen, Trang Quynh; Webb-Vargas, Yenny; Koning, Ina M; Stuart, Elizabeth A

We investigate a method to estimate the combined effect of multiple continuous/ordinal mediators on a binary outcome: 1) fit a structural equation model with probit link for the outcome and identity/probit link for continuous/ordinal mediators, 2) predict potential outcome probabilities, and 3) compute natural direct and indirect effects. Step 2 involves rescaling the latent continuous variable underlying the outcome to address residual mediator variance/covariance. We evaluate the estimation of risk-difference- and risk-ratio-based effects (RDs, RRs) using the ML, WLSMV and Bayes estimators in Mplus. Across most variations in path-coefficient and mediator-residual-correlation signs and strengths, and confounding situations investigated, the method performs well with all estimators, but favors ML/WLSMV for RDs with continuous mediators, and Bayes for RRs with ordinal mediators. Bayes outperforms WLSMV/ML regardless of mediator type when estimating RRs with small potential outcome probabilities and in two other special cases. An adolescent alcohol prevention study is used for illustration.

The Grandparent-Grandchild Relationship: Implications for Models of Intergenerational Communication

ERIC Educational Resources Information Center

Anderson, Karen; Harwood, Jake; Hummert, Mary Lee

2005-01-01

We report two studies which examine the age stereotypes in interactions model of intergenerational communication. We investigate whether stereotyping processes mediate the effects of various predictors on communication outcomes. Support emerges for the mediating role of stereotyping. The studies also examine relational factors finding support for…

Peer substance use as a mediator between early pubertal timing and adolescent substance use: longitudinal associations and moderating effect of maltreatment.

PubMed

Negriff, Sonya; Trickett, Penelope K

2012-11-01

Early pubertal timing has received considerable empirical support as a risk for adolescent substance use. However, few studies have examined the mediators linking these variables. Therefore, the aims of this study were (1) to examine peer substance use as a mediator between pubertal timing and adolescent substance use longitudinally and (2) to test gender and maltreatment experience as moderators of the mediational model. Data were obtained from time 1, 2, and 3 of a longitudinal study of maltreatment and development. At time 1 the sample was comprised of 303 maltreated and 151 comparison children aged 9-13 years (213 females and 241 males). Longitudinal mediation was tested using structural equation modeling and moderating effects were tested using multiple group analysis. Peer substance use mediated the relationship between early pubertal timing and later adolescent substance use for the total sample. Moderation analyses indicated this significant indirect effect did not differ for males and females. However, it did differ for maltreated versus comparison adolescents with the mediational effect only remaining significant for the comparison group. This is one of the first studies to examine peer substance use as a mediator of pubertal timing and adolescent substance use using a longitudinal design. Early maturing males are at equal risk to early maturing females for interacting with peers that may draw them into substance use. Additionally, the findings indicate that while peers are mediators for comparison adolescents a different mechanism may link early puberty to substance use for maltreated adolescents. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

Comments: Causal Interpretations of Mediation Effects

ERIC Educational Resources Information Center

Jo, Booil; Stuart, Elizabeth A.

2012-01-01

The authors thank Dr. Lindsay Page for providing a nice illustration of the use of the principal stratification framework to define causal effects, and a Bayesian model for effect estimation. They hope that her well-written article will help expose education researchers to these concepts and methods, and move the field of mediation analysis in…

Steps in the design, development and formative evaluation of obesity prevention-related behavior change trials.

PubMed

Baranowski, Tom; Cerin, Ester; Baranowski, Janice

2009-01-21

Obesity prevention interventions through dietary and physical activity change have generally not been effective. Limitations on possible program effectiveness are herein identified at every step in the mediating variable model, a generic conceptual framework for understanding how interventions may promote behavior change. To minimize these problems, and thereby enhance likely intervention effectiveness, four sequential types of formative studies are proposed: targeted behavior validation, targeted mediator validation, intervention procedure validation, and pilot feasibility intervention. Implementing these studies would establish the relationships at each step in the mediating variable model, thereby maximizing the likelihood that an intervention would work and its effects would be detected. Building consensus among researchers, funding agencies, and journal editors on distinct intervention development studies should avoid identified limitations and move the field forward.

Steps in the design, development and formative evaluation of obesity prevention-related behavior change trials

PubMed Central

Baranowski, Tom; Cerin, Ester; Baranowski, Janice

2009-01-01

Obesity prevention interventions through dietary and physical activity change have generally not been effective. Limitations on possible program effectiveness are herein identified at every step in the mediating variable model, a generic conceptual framework for understanding how interventions may promote behavior change. To minimize these problems, and thereby enhance likely intervention effectiveness, four sequential types of formative studies are proposed: targeted behavior validation, targeted mediator validation, intervention procedure validation, and pilot feasibility intervention. Implementing these studies would establish the relationships at each step in the mediating variable model, thereby maximizing the likelihood that an intervention would work and its effects would be detected. Building consensus among researchers, funding agencies, and journal editors on distinct intervention development studies should avoid identified limitations and move the field forward. PMID:19159476

Childhood maltreatment, personality disorders and 3-year persistence of adult alcohol and nicotine dependence in a national sample.

PubMed

Elliott, Jennifer C; Stohl, Malka; Wall, Melanie M; Keyes, Katherine M; Skodol, Andrew E; Eaton, Nicholas R; Shmulewitz, Dvora; Goodwin, Renee D; Grant, Bridget F; Hasin, Deborah S

2016-05-01

Persistent cases of alcohol and nicotine dependence are associated with considerable morbidity and mortality, and are predicted by childhood maltreatment and personality disorders. Our aim was to test whether personality disorders (individually or conjointly) mediate the relationship between childhood maltreatment and the persistence of dependence. Personality disorders, modeled dimensionally, were tested as mediators of the relationship between childhood maltreatment and the 3-year persistence of alcohol and nicotine dependence in participants in the National Epidemiologic Survey on Alcohol and Related Conditions (NESARC) who had current alcohol and nicotine dependence in their baseline interview. Individual personality disorders were assessed in separate models. Then, those that were significant were examined jointly in multiple mediator models to determine their total and unique effects. A large, nationally representative US survey. Participants ≥ 18 years who completed baseline and 3-year follow-up NESARC interviews who had baseline alcohol dependence (n = 1172; 68% male) or nicotine dependence (n = 4017; 52.9% male). Alcohol Use Disorder and Associated Disabilities Interview Schedule (AUDADIS-IV) measures of childhood maltreatment, personality disorders and alcohol/nicotine dependence. Individual models indicated that many personality disorders mediated the relationship between childhood maltreatment and the 3-year persistence of alcohol and nicotine dependence (each explaining 6-46% of the total effect, Ps < 0.05). In multiple mediator models, borderline and antisocial symptoms remained significant mediators, each explaining 20-37% of the total effect (Ps < 0.01). Personality disorder symptoms (especially borderline and antisocial) help explain the association between childhood maltreatment and persistent alcohol and nicotine dependence. © 2016 Society for the Study of Addiction.

Childhood maltreatment, personality disorders, and 3-year persistence of adult alcohol and nicotine dependence in a national sample

PubMed Central

Elliott, Jennifer C.; Stohl, Malka; Wall, Melanie M.; Keyes, Katherine M.; Skodol, Andrew E.; Eaton, Nicholas R.; Shmulewitz, Dvora; Goodwin, Renee D.; Grant, Bridget F.; Hasin, Deborah S.

2015-01-01

Background and Aims Persistent cases of alcohol and nicotine dependence are associated with considerable morbidity and mortality, and are predicted by childhood maltreatment and personality disorders. Our aim was to test whether personality disorders (individually or conjointly) mediate the relationship between childhood maltreatment and the persistence of dependence. Design Personality disorders, modeled dimensionally, were tested as mediators of the relationship between childhood maltreatment and the 3-year persistence of alcohol and nicotine dependence in participants in the National Epidemiologic Survey on Alcohol and Related Conditions (NESARC) who had current alcohol and nicotine dependence in their baseline interview. Individual personality disorders were assessed in separate models. Then, those that were significant were examined jointly in multiple mediator models to determine their total and unique effects. Setting A large, nationally representative United States survey. Participants Participants ≥18 years who completed baseline and 3-year follow-up NESARC interviews who had baseline alcohol dependence (n=1,172; 68% male) or nicotine dependence (n=4,017; 52.9% male). Measurements Alcohol Use Disorder and Associated Disabilities Interview Schedule (AUDADIS-IV) measures of childhood maltreatment, personality disorders, and alcohol/nicotine dependence. Findings Individual models indicated that many personality disorders mediated the relationship between childhood maltreatment and the 3-year persistence of alcohol and nicotine dependence (each explaining 6%–46% of the total effect, ps<0.05). In multiple mediator models, borderline and antisocial symptoms remained significant mediators, each explaining 20%–37% of the total effect (ps<0.01). Conclusions Personality disorder symptoms (especially borderline and antisocial) help explain the association between childhood maltreatment and persistent alcohol and nicotine dependence. PMID:26714255

Parentally Bereaved Children’s Grief: Self-system Beliefs as Mediators of the Relations between Grief and Stressors and Caregiver-child Relationship Quality

PubMed Central

Wolchik, Sharlene A.; Ma, Yue; Tein, Jenn-Yun; Sandler, Irwin N.; Ayers, Tim S.

2009-01-01

We investigated whether three self-system beliefs -- fear of abandonment, coping efficacy, and self-esteem -- mediated the relations between stressors and caregiver-child relationship quality and parentally bereaved youths’ general grief and intrusive grief thoughts. Cross-sectional (n=340 youth) and longitudinal (n=100 youth) models were tested. In the cross-sectional model, fear of abandonment mediated the effects of stressors and relationship quality on both measures of grief and coping efficacy mediated the path from relationship quality to general grief. Fear of abandonment showed a marginal prospective mediational relation between stressors and intrusive grief thoughts. After excluding the mediators, relationship quality showed a direct prospective relation to intrusive grief thoughts. PMID:18924290

Does functional disability mediate the pain-depression relationship in older adults with osteoarthritis? A longitudinal study in China.

PubMed

Wang, Qian; Jayasuriya, Rohan; Man, Wing Young Nicola; Fu, Hua

2015-03-01

Older adults with osteoarthritis have been found to be impaired in physical functioning and report higher levels of depression. This study examined the relationships between pain, functional disability, and depression to test the activity restriction model in a cohort of 176 older adults in China. This model states that disability is a mediator for the relationship between pain and depression. Other investigators have found that pain and disability were two independent correlates of depression. In both cross-sectional and longitudinal analyses, the authors found that disability is a mediator, using commonly accepted methods (indirect effect 44%, Sobel Z = 4.07, P < .001; 41%, Sobel Z = 3.45, P < .001, respectively). However, this mediation effect was not seen when the outcome was residualized with the baseline value. When the baseline level of depression is residualized, the effect size of the relationship is reduced, requiring larger sample size to test its effect. © 2012 APJPH.

TV, Social Media, and College Students' Binge Drinking Intentions: Moderated Mediation Models.

PubMed

Yang, Bo; Zhao, Xinyan

2018-01-01

Many studies to date have examined how media influence health-related behavior through social norms. However, most studies focused on traditional media. In the era of traditional and social media integration, our study advances health and mass communication scholarship by examining the influence of both traditional and social media mediated through social norms. Also, we examined a boundary condition for the norms-mediated media influence process. Namely, in the context of college binge drinking, we predict that exposure to TV and social media prodrinking messages can influence college students' binge drinking intentions through perceived peer descriptive and injunctive norms. We also predict that group identification will moderate this indirect effect. Our moderated mediation models were tested via structural equation modeling (N = 609). We found that college students' exposure to social media prodrinking messages indirectly influenced their binge drinking intentions via perceived injunctive norms, and students' identification with their peers moderated this indirect effect. However, neither descriptive nor injunctive norms mediated the influence of students' exposure to TV prodrinking messages on their binge drinking intentions. Theoretical and practical implications of the findings are discussed.

The role of neuroticism, perfectionism and depression in chronic fatigue syndrome. A structural equation modeling approach.

PubMed

Valero, Sergi; Sáez-Francàs, Naia; Calvo, Natalia; Alegre, José; Casas, Miquel

2013-10-01

Previous studies have reported consistent associations between Neuroticism, maladaptive perfectionism and depression with severity of fatigue in Chronic Fatigue Syndrome (CFS). Depression has been considered a mediator factor between maladaptive perfectionism and fatigue severity, but no studies have explored the role of neuroticism in a comparable theoretical framework. This study aims to examine for the first time, the role of neuroticism, maladaptive perfectionism and depression on the severity of CFS, analyzing several explanation models. A sample of 229 CFS patients were studied comparing four structural equation models, testing the role of mediation effect of depression severity in the association of Neuroticism and/or Maladaptive perfectionism on fatigue severity. The model considering depression severity as mediator factor between Neuroticism and fatigue severity is the only one of the explored models where all the structural modeling indexes have fitted satisfactorily (Chi square=27.01, p=0.079; RMSE=0.047, CFI=0.994; SRMR=0.033). Neuroticism is associated with CFS by the mediation effect of depression severity. This personality variable constitutes a more consistent factor than maladaptive perfectionism in the conceptualization of CFS severity. Copyright © 2013 Elsevier Inc. All rights reserved.

Burden and Cognitive Appraisal of Stroke Survivors' Informal Caregivers: An Assessment of Depression Model With Mediating and Moderating Effects.

PubMed

Tsai, Yi-Chen; Pai, Hsiang-Chu

2016-04-01

This study proposes and evaluates a model of depression that concerns the role of burden and cognitive appraisal as mediators or moderators of outcomes among stroke survivor caregivers. A total of 105 informal caregivers of stroke survivor completed the self-report measures of Caregiver Burden Inventory, Center for Epidemiologic Studies Depression Scale, and Cognitive Impact of Appraisal Scale. The Glasgow Coma Scale and Barthel Index were used by the researcher to examine the physical functional status of the survivor. Partial least squares (PLS) path modeling was used to estimate the parameters of a depression model that included mediating or moderating effects. The model shows that burden and impact of cognitive appraisal have a significant direct and indirect impact on depression, while survivor physical functional status does not have a direct impact. The model also demonstrates that burden and impact of cognitive appraisal separately play a mediating role between survivor physical functional status and caregiver depression. In addition, cognitive appraisal has a moderating influence on the relationship between burden and depression. Overall, survivor physical functional status, burden, and cognitive appraisal were the predictors of caregiver depression, explaining 47.1% of the variance. This study has shown that burden and cognitive appraisal are mediators that more fully explain the relationship between patient severity and caregiver depression. Copyright © 2015 Elsevier Inc. All rights reserved.

Distinguishing Between Risk Factors for Bulimia Nervosa, Binge Eating Disorder, and Purging Disorder.

PubMed

Allen, Karina L; Byrne, Susan M; Crosby, Ross D

2015-08-01

Binge eating disorder and purging disorder have gained recognition as distinct eating disorder diagnoses, but risk factors for these conditions have not yet been established. This study aimed to evaluate a prospective, mediational model of risk for the full range of binge eating and purging eating disorders, with attention to possible diagnostic differences. Specific aims were to determine, first, whether eating, weight and shape concerns at age 14 would mediate the relationship between parent-perceived childhood overweight at age 10 and a binge eating or purging eating disorder between age 15 and 20, and, second, whether this mediational model would differ across bulimia nervosa, binge eating disorder, and purging disorder. Participants (N = 1,160; 51 % female) were drawn from the Western Australian Pregnancy Cohort (Raine) Study, which has followed children from pre-birth to age 20. Eating disorders were assessed via self-report questionnaires when participants were aged 14, 17 and 20. There were 146 participants (82 % female) with a binge eating or purging eating disorder with onset between age 15 and 20 [bulimia nervosa = 81 (86 % female), binge eating disorder = 43 (74 % female), purging disorder = 22 (77 % female)]. Simple mediation analysis with bootstrapping was used to test the hypothesized model of risk, with early adolescent eating, weight and shape concerns positioned as a mediator between parent-perceived childhood overweight and later onset of a binge eating or purging eating disorder. Subsequently, a conditional process model (a moderated mediation model) was specified to determine if model pathways differed significantly by eating disorder diagnosis. In the simple mediation model, there was a significant indirect effect of parent-perceived childhood overweight on risk for a binge eating or purging eating disorder in late adolescence, mediated by eating, weight and shape concerns in early adolescence. In the conditional process model, this significant indirect effect was not moderated by eating disorder group. The results support a prospective model of risk that applies to bulimia nervosa, binge eating disorder and purging disorder. Common prevention approaches may be possible for bulimia nervosa, binge eating disorder and purging disorder.

A complete graphical criterion for the adjustment formula in mediation analysis.

PubMed

Shpitser, Ilya; VanderWeele, Tyler J

2011-03-04

Various assumptions have been used in the literature to identify natural direct and indirect effects in mediation analysis. These effects are of interest because they allow for effect decomposition of a total effect into a direct and indirect effect even in the presence of interactions or non-linear models. In this paper, we consider the relation and interpretation of various identification assumptions in terms of causal diagrams interpreted as a set of non-parametric structural equations. We show that for such causal diagrams, two sets of assumptions for identification that have been described in the literature are in fact equivalent in the sense that if either set of assumptions holds for all models inducing a particular causal diagram, then the other set of assumptions will also hold for all models inducing that diagram. We moreover build on prior work concerning a complete graphical identification criterion for covariate adjustment for total effects to provide a complete graphical criterion for using covariate adjustment to identify natural direct and indirect effects. Finally, we show that this criterion is equivalent to the two sets of independence assumptions used previously for mediation analysis.

Direct detection of exothermic dark matter with light mediator

DOE Office of Scientific and Technical Information (OSTI.GOV)

Geng, Chao-Qiang; Department of Physics, National Tsing Hua University,Hsinchu, Taiwan; Physics Division, National Center for Theoretical Sciences,Hsinchu, Taiwan

2016-08-05

We study the dark matter (DM) direct detection for the models with the effects of the isospin-violating couplings, exothermic scatterings, and/or the lightness of the mediator, proposed to relax the tension between the CDMS-Si signals and null experiments. In the light of the new updates of the LUX and CDMSlite data, we find that many of the previous proposals are now ruled out, including the Ge-phobic exothermic DM model and the Xe-phobic DM one with a light mediator. We also examine the exothermic DM models with a light mediator but without the isospin violation, and we are unable to identifymore » any available parameter space that could simultaneously satisfy all the experiments. The only models that can partially relax the inconsistencies are the Xe-phobic exothermic DM models with or without a light mediator. But even in this case, a large portion of the CDMS-Si regions of interest has been constrained by the LUX and SuperCDMS data.« less

Anxiety symptoms mediate the relationship between exposure to stressful negative life events and depressive symptoms: A conditional process modelling of the protective effects of resilience.

PubMed

Anyan, Frederick; Worsley, Lyn; Hjemdal, Odin

2017-10-01

Resilience has provided a useful framework that elucidates the effects of protective factors to overcome psychological adversities but studies that address the potential contingencies of resilience to protect against direct and indirect negative effects are lacking. These obvious gaps have also resulted in oversimplification of complex processes that can be clarified by moderated mediation associations. This study examines a conditional process modelling of the protective effects of resilience against indirect effects. Two separate samples were recruited in a cross-sectional survey from Australia and Norway to complete the Patient Health Questionnaire -9, Generalized Anxiety Disorder, Stressful Negative Life Events Questionnaire and the Resilience Scale for Adults. The final sample sizes were 206 (females=114; males=91; other=1) and 210 (females=155; males=55) for Australia and Norway respectively. Moderated mediation analyses were conducted across the samples. Anxiety symptoms mediated the relationship between exposure to stressful negative life events and depressive symptoms in both samples. Conditional indirect effects of exposure to stressful negative life events on depressive symptoms mediated by anxiety symptoms showed that high subgroup of resilience was associated with less effect of exposure to stressful negative life events through anxiety symptoms on depressive symptoms than the low subgroup of resilience. As a cross-sectional survey, the present study does not answer questions about causal processes despite the use of a conditional process modelling. These findings support that, resilience protective resources can protect against both direct and indirect - through other channels - psychological adversities. Copyright © 2017 Elsevier B.V. All rights reserved.

Executive Function, Behavioral Self-Regulation, and School Related Well-Being Did Not Mediate the Effect of School-Based Physical Activity on Academic Performance in Numeracy in 10-Year-Old Children. The Active Smarter Kids (ASK) Study.

PubMed

Aadland, Katrine N; Aadland, Eivind; Andersen, John R; Lervåg, Arne; Moe, Vegard F; Resaland, Geir K; Ommundsen, Yngvar

2018-01-01

Inconsistent findings exist for the effect of school-based physical activity interventions on academic performance. The Active Smarter Kids (ASK) study revealed a favorable intervention effect of school-based physical activity on academic performance in numeracy in a subsample of 10-year-old elementary schoolchildren performing poorer at baseline in numeracy. Aiming to explain this finding, we investigated the mediating effects of executive function, behavioral self-regulation, and school related well-being in the relation between the physical activity intervention and child's performance in numeracy. An ANCOVA model with latent variable structural equation modeling was estimated using data from 360 children (the lower third in academic performance in numeracy at baseline). The model consisted of the three latent factors as mediators; executive function, behavioral self-regulation, and school related well-being. We found no mediating effects of executive function, behavioral self-regulation or school related well-being in the relationship between the ASK intervention and academic performance in numeracy ( p ≥ 0.256). Our results suggest that the effect of the intervention on performance in numeracy in the present sample is not explained by change in executive function, behavioral self-regulation, or school related well-being. We suggest this finding mainly could be explained by the lack of effect of the intervention on the mediators, which might be due to an insufficient dose of physical activity. Trial registration: Clinicaltrials.gov registry, trial registration number: NCT02132494.

Executive Function, Behavioral Self-Regulation, and School Related Well-Being Did Not Mediate the Effect of School-Based Physical Activity on Academic Performance in Numeracy in 10-Year-Old Children. The Active Smarter Kids (ASK) Study

PubMed Central

Aadland, Katrine N.; Aadland, Eivind; Andersen, John R.; Lervåg, Arne; Moe, Vegard F.; Resaland, Geir K.; Ommundsen, Yngvar

2018-01-01

Inconsistent findings exist for the effect of school-based physical activity interventions on academic performance. The Active Smarter Kids (ASK) study revealed a favorable intervention effect of school-based physical activity on academic performance in numeracy in a subsample of 10-year-old elementary schoolchildren performing poorer at baseline in numeracy. Aiming to explain this finding, we investigated the mediating effects of executive function, behavioral self-regulation, and school related well-being in the relation between the physical activity intervention and child’s performance in numeracy. An ANCOVA model with latent variable structural equation modeling was estimated using data from 360 children (the lower third in academic performance in numeracy at baseline). The model consisted of the three latent factors as mediators; executive function, behavioral self-regulation, and school related well-being. We found no mediating effects of executive function, behavioral self-regulation or school related well-being in the relationship between the ASK intervention and academic performance in numeracy (p ≥ 0.256). Our results suggest that the effect of the intervention on performance in numeracy in the present sample is not explained by change in executive function, behavioral self-regulation, or school related well-being. We suggest this finding mainly could be explained by the lack of effect of the intervention on the mediators, which might be due to an insufficient dose of physical activity. Trial registration: Clinicaltrials.gov registry, trial registration number: NCT02132494. PMID:29541050

Quantitative pharmacokinetic-pharmacodynamic modelling of baclofen-mediated cardiovascular effects using BP and heart rate in rats.

PubMed

Kamendi, Harriet; Barthlow, Herbert; Lengel, David; Beaudoin, Marie-Eve; Snow, Debra; Mettetal, Jerome T; Bialecki, Russell A

2016-10-01

While the molecular pathways of baclofen toxicity are understood, the relationships between baclofen-mediated perturbation of individual target organs and systems involved in cardiovascular regulation are not clear. Our aim was to use an integrative approach to measure multiple cardiovascular-relevant parameters [CV: mean arterial pressure (MAP), systolic BP, diastolic BP, pulse pressure, heart rate (HR); CNS: EEG; renal: chemistries and biomarkers of injury] in tandem with the pharmacokinetic properties of baclofen to better elucidate the site(s) of baclofen activity. Han-Wistar rats were administered vehicle or ascending doses of baclofen (3, 10 and 30 mg·kg(-1) , p.o.) at 4 h intervals and baclofen-mediated changes in parameters recorded. A pharmacokinetic-pharmacodynamic model was then built by implementing an existing mathematical model of BP in rats. Final model fits resulted in reasonable parameter estimates and showed that the drug acts on multiple homeostatic processes. In addition, the models testing a single effect on HR, total peripheral resistance or stroke volume alone did not describe the data. A final population model was constructed describing the magnitude and direction of the changes in MAP and HR. The systems pharmacology model developed fits baclofen-mediated changes in MAP and HR well. The findings correlate with known mechanisms of baclofen pharmacology and suggest that similar models using limited parameter sets may be useful to predict the cardiovascular effects of other pharmacologically active substances. © 2016 The British Pharmacological Society.

Quantitative pharmacokinetic–pharmacodynamic modelling of baclofen‐mediated cardiovascular effects using BP and heart rate in rats

PubMed Central

Kamendi, Harriet; Barthlow, Herbert; Lengel, David; Beaudoin, Marie‐Eve; Snow, Debra

2016-01-01

Background and Purpose While the molecular pathways of baclofen toxicity are understood, the relationships between baclofen‐mediated perturbation of individual target organs and systems involved in cardiovascular regulation are not clear. Our aim was to use an integrative approach to measure multiple cardiovascular‐relevant parameters [CV: mean arterial pressure (MAP), systolic BP, diastolic BP, pulse pressure, heart rate (HR); CNS: EEG; renal: chemistries and biomarkers of injury] in tandem with the pharmacokinetic properties of baclofen to better elucidate the site(s) of baclofen activity. Experimental Approach Han‐Wistar rats were administered vehicle or ascending doses of baclofen (3, 10 and 30 mg·kg−1, p.o.) at 4 h intervals and baclofen‐mediated changes in parameters recorded. A pharmacokinetic–pharmacodynamic model was then built by implementing an existing mathematical model of BP in rats. Key Results Final model fits resulted in reasonable parameter estimates and showed that the drug acts on multiple homeostatic processes. In addition, the models testing a single effect on HR, total peripheral resistance or stroke volume alone did not describe the data. A final population model was constructed describing the magnitude and direction of the changes in MAP and HR. Conclusions and Implications The systems pharmacology model developed fits baclofen‐mediated changes in MAP and HR well. The findings correlate with known mechanisms of baclofen pharmacology and suggest that similar models using limited parameter sets may be useful to predict the cardiovascular effects of other pharmacologically active substances. PMID:27448216

Covariate Measurement Error Correction Methods in Mediation Analysis with Failure Time Data

PubMed Central

Zhao, Shanshan

2014-01-01

Summary Mediation analysis is important for understanding the mechanisms whereby one variable causes changes in another. Measurement error could obscure the ability of the potential mediator to explain such changes. This paper focuses on developing correction methods for measurement error in the mediator with failure time outcomes. We consider a broad definition of measurement error, including technical error and error associated with temporal variation. The underlying model with the ‘true’ mediator is assumed to be of the Cox proportional hazards model form. The induced hazard ratio for the observed mediator no longer has a simple form independent of the baseline hazard function, due to the conditioning event. We propose a mean-variance regression calibration approach and a follow-up time regression calibration approach, to approximate the partial likelihood for the induced hazard function. Both methods demonstrate value in assessing mediation effects in simulation studies. These methods are generalized to multiple biomarkers and to both case-cohort and nested case-control sampling design. We apply these correction methods to the Women's Health Initiative hormone therapy trials to understand the mediation effect of several serum sex hormone measures on the relationship between postmenopausal hormone therapy and breast cancer risk. PMID:25139469

Covariate measurement error correction methods in mediation analysis with failure time data.

PubMed

Zhao, Shanshan; Prentice, Ross L

2014-12-01

Mediation analysis is important for understanding the mechanisms whereby one variable causes changes in another. Measurement error could obscure the ability of the potential mediator to explain such changes. This article focuses on developing correction methods for measurement error in the mediator with failure time outcomes. We consider a broad definition of measurement error, including technical error, and error associated with temporal variation. The underlying model with the "true" mediator is assumed to be of the Cox proportional hazards model form. The induced hazard ratio for the observed mediator no longer has a simple form independent of the baseline hazard function, due to the conditioning event. We propose a mean-variance regression calibration approach and a follow-up time regression calibration approach, to approximate the partial likelihood for the induced hazard function. Both methods demonstrate value in assessing mediation effects in simulation studies. These methods are generalized to multiple biomarkers and to both case-cohort and nested case-control sampling designs. We apply these correction methods to the Women's Health Initiative hormone therapy trials to understand the mediation effect of several serum sex hormone measures on the relationship between postmenopausal hormone therapy and breast cancer risk. © 2014, The International Biometric Society.

Are effects of emotion expression on trait impressions mediated by babyfaceness? Evidence from connectionist modeling.

PubMed

Zebrowitz, Leslie A; Kikuchi, Masako; Fellous, Jean-Marc

2007-05-01

Two studies provided evidence that bolsters the Marsh, Adams, and Kleck hypothesis that the morphology of certain emotion expressions reflects an evolved adaptation to mimic babies or mature adults. Study 1 found differences in emotion expressions' resemblance to babies using objective indices of babyfaceness provided by connectionist models that are impervious to overlapping cultural stereotypes about babies and the emotions. Study 2 not only replicated parallels between impressions of certain emotions and babies versus adults but also showed that objective indices of babyfaceness partially mediated impressions of the emotion expressions. babyface effects were independent of strong effects of attractiveness, and babyfaceness did not mediate impressions of happy expressions, to which the evolutionary hypothesis would not apply.

Personality and job performance: test of the mediating effects of motivation among sales representatives.

PubMed

Barrick, Murray R; Stewart, Greg L; Piotrowski, Mike

2002-02-01

Research shows consistent relations between personality and job performance. In this study the authors develop and test a model of job performance that examines the mediating effects of cognitive-motivational work orientations on the relationships between personality traits and performance in a sales job (N = 164). Covariance structural analyses revealed proximal motivational variables to be influential mechanisms through which distal personality traits affect job performance. Specifically, striving for status and accomplishment mediate the effects of Extraversion and Conscientiousness on ratings of sales performance. Although Agreeableness was related to striving for communion, neither Agreeableness nor communion striving was related to success in this sales job. The importance of the proposed motivational orientations model is discussed.

Social support as a mediator between job control and psychological strain.

PubMed

Blanch, Angel

2016-05-01

Social support is a key influencing factor on health, and one of the main dimensions of the Demand - Control - Support (DCS) model within the occupational health field. The buffer hypothesis of the DCS determines that job control and social support relieve the effects of a high job demand on health. This hypothesis has been evaluated in several studies to predict worker's health, even though it has yielded ambiguous and inconclusive results. This study evaluated whether social support mediated the effect of job demand or job control on job strain. This mediation mechanism might represent a plausible and coherent alternative to the buffer hypothesis deserving to be analyzed within this field. Two models considering support as the mediator variable in the explanation of job strain were assessed with a group of administrative and technical workers (N = 281). While there was no evidence for support behaving as a mediator variable between demand and job strain, social support was a consistent mediator in the association of job control with job strain. The effect of job control on job strain was fully mediated by social support from supervisors and coworkers. The role of social support as a mediator implicates that the prevention of psychosocial stressors in the job place should place a stronger emphasis on improving social relationships at work. Copyright © 2016 Elsevier Ltd. All rights reserved.

Shared Authentic Leadership in Research Teams: Testing a Multiple Mediation Model.

PubMed

Guenter, Hannes; Gardner, William L; Davis McCauley, Kelly; Randolph-Seng, Brandon; Prabhu, Veena P

2017-12-01

Research teams face complex leadership and coordination challenges. We propose shared authentic leadership (SAL) as a timely approach to addressing these challenges. Drawing from authentic and functional leadership theories, we posit a multiple mediation model that suggests three mechanisms whereby SAL influences team effectiveness: shared mental models (SMM), team trust, and team coordination. To test our hypotheses, we collected survey data on leadership and teamwork within 142 research teams that recently published an article in a peer-reviewed management journal. The results indicate team coordination represents the primary mediating mechanism accounting for the relationship between SAL and research team effectiveness. While teams with high trust and SMM felt more successful and were more satisfied, they were less successful in publishing in high-impact journals. We also found the four SAL dimensions (i.e., self-awareness, relational transparency, balanced processing, and internalized moral perspective) to associate differently with team effectiveness.

Shared Authentic Leadership in Research Teams: Testing a Multiple Mediation Model

PubMed Central

Guenter, Hannes; Gardner, William L.; Davis McCauley, Kelly; Randolph-Seng, Brandon; Prabhu, Veena P.

2017-01-01

Research teams face complex leadership and coordination challenges. We propose shared authentic leadership (SAL) as a timely approach to addressing these challenges. Drawing from authentic and functional leadership theories, we posit a multiple mediation model that suggests three mechanisms whereby SAL influences team effectiveness: shared mental models (SMM), team trust, and team coordination. To test our hypotheses, we collected survey data on leadership and teamwork within 142 research teams that recently published an article in a peer-reviewed management journal. The results indicate team coordination represents the primary mediating mechanism accounting for the relationship between SAL and research team effectiveness. While teams with high trust and SMM felt more successful and were more satisfied, they were less successful in publishing in high-impact journals. We also found the four SAL dimensions (i.e., self-awareness, relational transparency, balanced processing, and internalized moral perspective) to associate differently with team effectiveness. PMID:29187779

Relationships among symptom severity, coping styles, and quality of life in community-dwelling women with urinary incontinence: a multiple mediator model.

PubMed

Xu, Dongjuan; Liu, Nana; Qu, Haili; Chen, Liqin; Wang, Kefang

2016-01-01

To investigate the relationships among symptom severity, coping styles, and quality of life (QOL) in community-dwelling women with urinary incontinence (UI). A total of 592 women with UI participated in this cross-sectional study. Bivariate Pearson's correlation was used to examine the correlations between symptom severity, coping styles, and QOL. Multivariate regression models and Sobel tests were used to test the mediating effect of coping styles. Additionally, a multiple mediator model was used to examine the mediating role of coping styles collectively. All regression models were adjusted for age, education, marital status, income, duration of UI, and type of UI. Participants tended to use avoidant and palliative coping styles and not use instrumental coping style. Avoidant and palliative coping styles were associated with poor QOL, and partially mediated the association between symptom severity and QOL. Nearly 73% of the adverse effect of symptom severity on QOL was mediated by avoidant and palliative coping styles. The use of avoidant and palliative coping styles was higher with more severe urine leakage, and QOL tended to be poorer. Coping styles should be addressed in UI management. It may be of particular value to look closely at negative coping styles and implement education and training of patients in improving their coping skills related to managing UI, which will in turn improve their QOL.

Body mass index, depression, and suicidality: The role of self-esteem in bariatric surgery candidates.

PubMed

Yusufov, Miryam; Dalrymple, Kristy; Bernstein, Michael H; Walsh, Emily; Rosenstein, Lia; Chelminski, Iwona; Zimmerman, Mark

2017-01-15

Previous research suggests a relationship between weight and depression/suicidality, although few studies have examined the mechanisms underlying this association. This study examined the mediating role of self-esteem in the relationship between BMI and depression/suicidality, as well as the moderating role of gender in the mediated pathways. As part of a screening process in consideration for bariatric surgery, 3,101 adults (81.4% female, 18.6% male) were assessed one time. Five univariate mediation and five univariate moderated-mediation models were hypothesized and analyzed. For the mediation models, we entered five outcome variables separately: 1) severity of depressed mood, 2) diagnosis of Major Depressive Disorder, 3) lifetime history of suicide attempts, 4) suicidal ideation at the time of evaluation, and 5) severity of suicidality, BMI as the independent variable, and self-esteem as the mediator. For the moderated-mediated models, gender was examined as a moderator to examine whether self-esteem was a stronger mediator for one gender, compared to the other. Findings supported the mediating role of self-esteem across all five outcomes. Further, the mediated effect was moderated by gender, such that the mediation effect was stronger for males, compared to females. The majority of the sample consisted of White females, limiting broad applicability of findings. All variables were assessed simultaneously, at baseline, limiting the ability to make causal attributions. Study findings suggest that self-esteem may help explain the relationship between BMI and depression/suicidality, particularly for men. Thus, interventions targeting self-esteem may be useful for improving psychological outcomes among those presenting for bariatric surgery. Copyright © 2016 Elsevier B.V. All rights reserved.

Behavioral Self-Regulation and Weight-Related Behaviors in Inner-City Adolescents: A Model of Direct and Indirect Effects

PubMed Central

Isasi, Carmen R.; Wills, Thomas A.

2012-01-01

Background This study examined the association of two distinct self-regulation constructs, effortful control and dysregulation, with weight-related behaviors in adolescents and tested whether these effects were mediated by self-efficacy variables. Methods A school-based survey was conducted with 1771 adolescents from 11 public schools in the Bronx, New York. Self-regulation was assessed by multiple indicators and defined as two latent constructs. Dependent variables included fruit/vegetable intake, intake of snack/junk food, frequency of physical activity, and time spent in sedentary behaviors. Structural equation modeling examined the relation of effortful control and dysregulation to lifestyle behaviors, with self-efficacy variables as possible mediators. Results Study results showed that effortful control had a positive indirect effect on fruit and vegetable intake, mediated by self-efficacy, as well as a direct effect. Effortful control also had a positive indirect effect on physical activity, mediated by self-efficacy. Dysregulation had direct effects on intake of junk food/snacks and time spent in sedentary behaviors. Conclusions These findings indicate that self-regulation characteristics are related to diet and physical activity and that some of these effects are mediated by self-efficacy. Different effects were noted for the two domains of self-regulation. Prevention researchers should consider including self-regulation processes in programs to improve health behaviors in adolescents. PMID:23243551

Nanorod mediated surface plasmon resonance sensor based on effective medium theory

USDA-ARS?s Scientific Manuscript database

A novel nanorod mediated surface plasmon resonance (SPR) sensor was investigated for enhancing sensitivity of the sensor. The theoretical model containing an anisotropic layer of nanorod was investigated using four-layer Fresnel equations and effective medium theory. The properties of the nanorod me...

Counterfactual Graphical Models for Longitudinal Mediation Analysis with Unobserved Confounding

ERIC Educational Resources Information Center

Shpitser, Ilya

2013-01-01

Questions concerning mediated causal effects are of great interest in psychology, cognitive science, medicine, social science, public health, and many other disciplines. For instance, about 60% of recent papers published in leading journals in social psychology contain at least one mediation test (Rucker, Preacher, Tormala, & Petty, 2011).…

Estimating Causal Effects in Mediation Analysis Using Propensity Scores

ERIC Educational Resources Information Center

Coffman, Donna L.

2011-01-01

Mediation is usually assessed by a regression-based or structural equation modeling (SEM) approach that we refer to as the classical approach. This approach relies on the assumption that there are no confounders that influence both the mediator, "M", and the outcome, "Y". This assumption holds if individuals are randomly…

Violence Exposure and Psychopathology in Urban Youth: The Mediating Role of Posttraumatic Stress

ERIC Educational Resources Information Center

Ruchkin, Vladislav; Henrich, Christopher C.; Jones, Stephanie M.; Vermeiren, Robert; Schwab-Stone, Mary

2007-01-01

Understanding the mechanisms underlying the development of violence exposure sequelae is essential to providing effective treatments for traumatized youth. This longitudinal study examined the mediating role of posttraumatic stress in the relationship between violence exposure and psychopathology, and compared the mediated models by gender. Urban…

Applying Adult Behavior Change Theory to Support Mediator-Based Intervention Implementation

ERIC Educational Resources Information Center

Sanetti, Lisa M. H.; Kratochwill, Thomas R.; Long, Anna C. J.

2013-01-01

A majority of evidence-based interventions in schools are delivered through consultation models and are implemented by a mediator, such as a teacher. Research indicates that mediators do not always adequately implement adopted evidence-based interventions, limiting their effectiveness in transforming student outcomes. We propose that to transform…

Participation in Athletics and Female Sexual Risk Behavior: The Evaluation of Four Causal Structures.

ERIC Educational Resources Information Center

Dodge, Tonya; Jaccard, James

2002-01-01

Compared sexual risk behavior of female athletes and nonathletes. Examined mediation, reverse mediation, spurious effects, and moderated causal models, using as potential mediators physical development, educational aspirations, self-esteem, attitudes toward pregnancy, involvement in a romantic relationship, age, ethnicity, and social class. Found…

Distinguishing Mediational Models and Analyses in Clinical Psychology: Atemporal Associations Do Not Imply Causation.

PubMed

Winer, E Samuel; Cervone, Daniel; Bryant, Jessica; McKinney, Cliff; Liu, Richard T; Nadorff, Michael R

2016-09-01

A popular way to attempt to discern causality in clinical psychology is through mediation analysis. However, mediation analysis is sometimes applied to research questions in clinical psychology when inferring causality is impossible. This practice may soon increase with new, readily available, and easy-to-use statistical advances. Thus, we here provide a heuristic to remind clinical psychological scientists of the assumptions of mediation analyses. We describe recent statistical advances and unpack assumptions of causality in mediation, underscoring the importance of time in understanding mediational hypotheses and analyses in clinical psychology. Example analyses demonstrate that statistical mediation can occur despite theoretical mediation being improbable. We propose a delineation of mediational effects derived from cross-sectional designs into the terms temporal and atemporal associations to emphasize time in conceptualizing process models in clinical psychology. The general implications for mediational hypotheses and the temporal frameworks from within which they may be drawn are discussed. © 2016 Wiley Periodicals, Inc.

Social comparison and perceived breach of psychological contract: their effects on burnout in a multigroup analysis.

PubMed

Cantisano, Gabriela Topa; Domínguez, J Francisco Morales; García, J Luis Caeiro

2007-05-01

This study focuses on the mediator role of social comparison in the relationship between perceived breach of psychological contract and burnout. A previous model showing the hypothesized effects of perceived breach on burnout, both direct and mediated, is proposed. The final model reached an optimal fit to the data and was confirmed through multigroup analysis using a sample of Spanish teachers (N = 401) belonging to preprimary, primary, and secondary schools. Multigroup analyses showed that the model fit all groups adequately.

Parental mediation and cyberbullying - a longitudinal study.

PubMed

Chng, Grace S; Liau, Albert; Khoo, Angeline; Li, Dongdong

2014-01-01

Parents use active and restrictive mediation strategies to guide and regulate children's online participation and the online risks they encounter. However, changes in parental mediation do occur over time and the effectiveness of these strategies on cyberbullying demands for further empirical investigation. The current study addresses these issues with a sample of 1084 students (49% girls) in a longitudinal, three-wave design. Gender differences were tested via multi-group analyses. Longitudinal growth models showed that parental use of both active and restrictive mediation decreased over time. For both types of mediation, the mean rate of change had a significant effect on boys' engagement in cyberbullying, but not for girls. Initial levels of restrictive mediation, but not active mediation, were found to be significantly predictive of cyberbullying in both genders. Girls had higher initial levels of both parental mediation types in comparison to boys. The results reveal that the effectiveness of active and restrictive mediation in relation to students' cyberbullying differs and informs us on gender differences. The implications of these results for parental education in online mediation are discussed.

The mediating role of interpersonal cognition on the relationships between personality and adolescent ego development.

PubMed

Liu, Yih-Lan

2013-01-01

The author investigated whether interpersonal cognition mediated the relationships between defense, social sensitivity, and ego development. Participants (N = 616; M age = 15.66 years, SD = .52 year; 276 boys) from northwestern Taiwan completed a battery of questionnaires. Structural equation modeling and mediation analyses supported the hypothesis that interpersonal cognition would mediate the path between defense and ego development, and the path between social sensitivity and ego development. Defense and social sensitivity were found to have direct effects on ego development. The study provides evidence of the mediating effect of interpersonal cognition on the association between personality and ego development.

[Interparental conflict and mental health in children and adolescents: the mediating effect of self-concept].

PubMed

Gao, Meng; Li, Yu-Chen; Zhang, Wei

2017-04-01

To examine the mediating effect of self-concept between interparental conflict and mental health in children and adolescents. A total of 689 students (10-18 years) were surveyed using the convenient sampling method, and their mental health, self-concept, and interparental conflict were examined by the general status questionnaire, Strengths and Difficulties Questionnaire, Self-Description Questionnaire, and Children's Perception of Interparental Conflict Scale. Structural equation modeling (SEM) and simultaneous analysis of several groups were used to construct the mediator model and analyze the data, respectively. The Bootstrap method was used to assess the significance of the mediating effects. Interparental conflict was positively correlated with mental health of children and adolescents (P<0.05), but was negatively correlated with self-concept (P<0.01). Self-concept was negatively correlated with mental health (P<0.01). Self-concept had a partial (60%) mediating effect between interparental conflict and mental health. Academic stage, but not gender, had a regulatory role on interparental conflict, mental health, and self-concept. Self-concept plays an important role between interparental conflict and mental health. It is necessary to improve self-concept level in children and adolescents exposed to interparental conflict.

Personal and Environmental Resources Mediate the Positivity-Emotional Dysfunction Relationship.

PubMed

Lehrer, H Matthew; Janus, Katherine C; Gloria, Christian T; Steinhardt, Mary A

2017-03-01

We investigated the relationships among positivity, perceived personal and environmental resources, and emotional dysfunction in adolescent girls. We hypothesized that perceived resources would mediate the relationship between positivity and emotional dysfunction. Participants (N = 510) attending an all-girls public school completed a survey assessing emotional dysfunction (depressive symptoms and perceived stress), positivity (positive/negative emotions), and personal/ environmental resources (resilience, hope, percent adaptive coping, community connectedness, social support, and school connectedness). Perceived resources were combined into one latent variable, and structural equation modeling tested the mediating effect of perceived resources on the relationship between positivity and emotional dysfunction. The model accounted for 63% of the variance in emotional dysfunction. Positivity exerted a significant direct effect on emotional dysfunction (β = -.14, p < .01), but its influence was primarily mediated through perceived resources (indirect effect: β = -.43, p < .001). The impact of positivity on emotional dysfunction is primarily but not entirely mediated by perceived personal and environmental resources. Schools should consider strategies to enhance experiences of positive emotions and/or decrease experiences of negative emotions, in conjunction with encouraging student awareness and development of personal and environmental resources.

Characteristics of the home food environment that mediate immediate and sustained increases in child fruit and vegetable consumption: mediation analysis from the Healthy Habits cluster randomised controlled trial.

PubMed

Wyse, Rebecca; Wolfenden, Luke; Bisquera, Alessandra

2015-09-17

The home food environment can influence the development of dietary behaviours in children, and interventions that modify characteristics of the home food environment have been shown to increase children's fruit and vegetable consumption. However to date, interventions to increase children's fruit and vegetable consumption have generally produced only modest effects. Mediation analysis can help in the design of more efficient and effective interventions by identifying the mechanisms through which interventions have an effect. This study aimed to identify characteristics of the home food environment that mediated immediate and sustained increases in children's fruit and vegetable consumption following the 4-week Healthy Habits telephone-based parent intervention. Analysis was conducted using 2-month (immediate) and 12-month (sustained) follow-up data from a cluster randomised control trial of a home food environment intervention to increase the fruit and vegetable consumption of preschool children. Using recursive path analysis, a series of mediation models were created to investigate the direct and indirect effects of immediate and sustained changes to characteristics of the home food environment (fruit and vegetable availability, accessibility, parent intake, parent providing behaviour, role-modelling, mealtime eating practices, child feeding strategies, and pressure to eat), on the change in children's fruit and vegetable consumption. Of the 394 participants in the randomised trial, 357 and 329 completed the 2- and 12-month follow-up respectively. The final mediation model suggests that the effect of the intervention on the children's fruit and vegetable consumption was mediated by parent fruit and vegetable intake and parent provision of these foods at both 2- and 12-month follow-up. Analysis of data from the Healthy Habits trial suggests that two environmental variables (parental intake and parent providing) mediate the immediate and sustained effect of the intervention, and it is recommended these variables be targeted in subsequent home food environment interventions to bring about immediate and sustained changes in child fruit and vegetable intake. ACTRN12609000820202 .

Trait Self-Control, Identified-Introjected Religiosity and Health-Related-Feelings in Healthy Muslims: A Structural Equation Model Analysis

PubMed Central

Briki, Walid; Chaouachi, Anis; Patrick, Thomas; Chamari, Karim

2015-01-01

Aim The present study attempted to test McCullough and Willoughby’s hypothesis that self-control mediates the relationships between religiosity and psychosocial outcomes. Specifically, this study examined whether trait self-control (TSC) mediates the relationship of identified-introjected religiosity with positive and negative health-related-feelings (HRF) in healthy Muslims. Methods Two hundred eleven French-speaking participants (116 females, 95 males; Mage = 28.15, SDage = 6.90) answered questionnaires. One hundred ninety participants were retained for the analyses because they reported to be healthy (105 females, 85 males; Mage = 27.72, SDage = 6.80). To examine the relationships between religiosity, TSC and HRF, two competing mediation models were tested using structural equation model analysis: While a starting model used TSC as mediator of the religiosity-HRF relationship, an alternative model used religiosity as mediator of the TSC-HRF relationship. Results The findings revealed that TSC mediated the relationship between identified religiosity and positive HRF, and that identified religiosity mediated the relationship between TSC and positive and negative HRF, thereby validating both models. Moreover, the comparison of both models showed that the starting model explained 13.211% of the variance (goodness of fit = 1.000), whereas the alternative model explained 6.877% of the variance (goodness of fit = 0.987). Conclusion These results show that the starting model is the most effective model to account for the relationships between religiosity, TSC, and HRF. Therefore, this study provides initial insights into how religiosity influences psychological health through TSC. Important practical implications for the religious education are suggested. PMID:25962179

Trait self-control, identified-introjected religiosity and health-related-feelings in healthy muslims: a structural equation model analysis.

PubMed

Briki, Walid; Aloui, Asma; Bragazzi, Nicola Luigi; Chaouachi, Anis; Patrick, Thomas; Chamari, Karim

2015-01-01

The present study attempted to test McCullough and Willoughby's hypothesis that self-control mediates the relationships between religiosity and psychosocial outcomes. Specifically, this study examined whether trait self-control (TSC) mediates the relationship of identified-introjected religiosity with positive and negative health-related-feelings (HRF) in healthy Muslims. Two hundred eleven French-speaking participants (116 females, 95 males; Mage = 28.15, SDage = 6.90) answered questionnaires. One hundred ninety participants were retained for the analyses because they reported to be healthy (105 females, 85 males; Mage = 27.72, SDage = 6.80). To examine the relationships between religiosity, TSC and HRF, two competing mediation models were tested using structural equation model analysis: While a starting model used TSC as mediator of the religiosity-HRF relationship, an alternative model used religiosity as mediator of the TSC-HRF relationship. The findings revealed that TSC mediated the relationship between identified religiosity and positive HRF, and that identified religiosity mediated the relationship between TSC and positive and negative HRF, thereby validating both models. Moreover, the comparison of both models showed that the starting model explained 13.211% of the variance (goodness of fit = 1.000), whereas the alternative model explained 6.877% of the variance (goodness of fit = 0.987). These results show that the starting model is the most effective model to account for the relationships between religiosity, TSC, and HRF. Therefore, this study provides initial insights into how religiosity influences psychological health through TSC. Important practical implications for the religious education are suggested.

Emergency room nurses' pathway to turnover intention: a moderated serial mediation analysis.

PubMed

Bruyneel, Luk; Thoelen, Tom; Adriaenssens, Jef; Sermeus, Walter

2017-04-01

The aim of this study was to explore the association between the quality of the work environment, job characteristics, demographic characteristics and a pathway of job satisfaction, emotional exhaustion and turnover intention among nurses in emergency departments and perform subgroup analyses. Turnover intention among nurses is high. Multiple causes have been described, mostly in large studies of nurses working on general wards, often without considering complementarity of conceptual models and showing scant interest in the consistency of associations across subgroups of nurses. Cross-sectional multicentre survey. Convenience sample of 294 nurses in 11 Belgian emergency departments during 2014-2015. Indirect effects in the form of mediation and serial mediation were estimated to assess the association between work environment (Magnet model), job characteristics (Job Demand Control Support model) and turnover intention via job satisfaction and emotional exhaustion. Consistency of these indirect effects across subgroups of nurses was examined using moderated mediation analysis (conditional indirect effects). Several Magnet and Job Demand Control Support dimensions were related to turnover intention, either via job dissatisfaction (mediation) or via job satisfaction and emotional exhaustion (serial mediation). In the case of social support from supervisor, these indirect effects were only significant for female nurses, among whom turnover intention was higher. Last, nurses with more years of experience were less likely to indicate turnover intention. To maximize prevention of turnover intention at emergency departments, interventions could target early career nurses, work environment and job characteristics. Female nurses in particular may also benefit from improved social support from their supervisor. © 2016 John Wiley & Sons Ltd.

Be Friendly, Stay Well: The Effects of Job Resources on Well-Being in a Discriminatory Work Environment.

PubMed

Di Marco, Donatella; Arenas, Alicia; Giorgi, Gabriele; Arcangeli, Giulio; Mucci, Nicola

2018-01-01

Many studies have focused on the negative effects of discrimination on workers' well-being. However, discrimination does not affect just victims but also those people who witness discriminatory acts or who perceived they are working in a discriminatory work environment. Although perceiving a discriminatory work environment might be a stressor, the presence of job resources might counteract its negative effects, as suggested by the Job Demand-Resources model. The goal of this study is to test the effect of perceiving a discriminatory work environment on workers' psychological well-being when job autonomy and co-workers and supervisor support act as mediator and moderators respectively. To test the moderated mediation model data were gathered with a sample of Italian 114 truckers. Results demonstrated that job autonomy partially mediates the relationship between perceiving a discriminatory work environment and workers' well-being. Main interactional effects have been observed when co-workers support is introduced in the model as moderator, while no main interactional effects exist when supervisor support is introduced. Theoretical and practical implications are discussed.

Be Friendly, Stay Well: The Effects of Job Resources on Well-Being in a Discriminatory Work Environment

PubMed Central

Di Marco, Donatella; Arenas, Alicia; Giorgi, Gabriele; Arcangeli, Giulio; Mucci, Nicola

2018-01-01

Many studies have focused on the negative effects of discrimination on workers’ well-being. However, discrimination does not affect just victims but also those people who witness discriminatory acts or who perceived they are working in a discriminatory work environment. Although perceiving a discriminatory work environment might be a stressor, the presence of job resources might counteract its negative effects, as suggested by the Job Demand-Resources model. The goal of this study is to test the effect of perceiving a discriminatory work environment on workers’ psychological well-being when job autonomy and co-workers and supervisor support act as mediator and moderators respectively. To test the moderated mediation model data were gathered with a sample of Italian 114 truckers. Results demonstrated that job autonomy partially mediates the relationship between perceiving a discriminatory work environment and workers’ well-being. Main interactional effects have been observed when co-workers support is introduced in the model as moderator, while no main interactional effects exist when supervisor support is introduced. Theoretical and practical implications are discussed. PMID:29666596

Predictive power of food web models based on body size decreases with trophic complexity.

PubMed

Jonsson, Tomas; Kaartinen, Riikka; Jonsson, Mattias; Bommarco, Riccardo

2018-05-01

Food web models parameterised using body size show promise to predict trophic interaction strengths (IS) and abundance dynamics. However, this remains to be rigorously tested in food webs beyond simple trophic modules, where indirect and intraguild interactions could be important and driven by traits other than body size. We systematically varied predator body size, guild composition and richness in microcosm insect webs and compared experimental outcomes with predictions of IS from models with allometrically scaled parameters. Body size was a strong predictor of IS in simple modules (r 2  = 0.92), but with increasing complexity the predictive power decreased, with model IS being consistently overestimated. We quantify the strength of observed trophic interaction modifications, partition this into density-mediated vs. behaviour-mediated indirect effects and show that model shortcomings in predicting IS is related to the size of behaviour-mediated effects. Our findings encourage development of dynamical food web models explicitly including and exploring indirect mechanisms. © 2018 John Wiley & Sons Ltd/CNRS.

Z boson mediated dark matter beyond the effective theory

DOE PAGES

Kearney, John; Orlofsky, Nicholas; Pierce, Aaron

2017-02-17

Here, direct detection bounds are beginning to constrain a very simple model of weakly interacting dark matter—a Majorana fermion with a coupling to the Z boson. In a particularly straightforward gauge-invariant realization, this coupling is introduced via a higher-dimensional operator. While attractive in its simplicity, this model generically induces a large ρ parameter. An ultraviolet completion that avoids an overly large contribution to ρ is the singlet-doublet model. We revisit this model, focusing on the Higgs blind spot region of parameter space where spin-independent interactions are absent. This model successfully reproduces dark matter with direct detection mediated by the Zmore » boson but whose cosmology may depend on additional couplings and states. Future direct detection experiments should effectively probe a significant portion of this parameter space, aside from a small coannihilating region. As such, Z-mediated thermal dark matter as realized in the singlet-doublet model represents an interesting target for future searches.« less

Burnout and Engagement as Mediators in the Relationship between Work Characteristics and Turnover Intentions across Two Ibero-American Nations.

PubMed

Gabel Shemueli, Rachel; Dolan, Simon L; Suárez Ceretti, Adriana; Nuñez Del Prado, Pamela

2016-12-01

This study examines the mediating effects of burnout and engagement on the relationships between work characteristics (work overload and social support) and turnover intentions in the nursing community of two Ibero-American countries within the job demands-resources model. The sample consists of 316 registered nurses employed in Uruguay and 502 employed in Spain. We used multiple structural equation modelling analyses. The proposed model fit the data for both nursing samples. Burnout was found to fully mediate the relationship between work overload and turnover intention, whereas work engagement partially mediates the relationship between social support and turnover intention. The results contribute to our understanding of the potential applicability of two leading empirical models and of the dynamic relationship between work characteristics and turnover intentions through work engagement and burnout. Researchers should continue to focus on gaining a broader understanding of the effects of work characteristics in healthcare facilities and the associated organizational outcomes. Copyright © 2015 John Wiley & Sons, Ltd. Copyright © 2015 John Wiley & Sons, Ltd.

Relationship between peer victimization and school adjustment in sixth-grade students: investigating mediation effects.

PubMed

Wei, Hsi-Sheng; Williams, James Herbert

2004-10-01

Peer victimization is a common occurrence in school settings. This study investigated the relationship between peer victimization and school adjustment in a sample of 1,022 sixth-grade students. Measures used in this study include peer victimization, perceived peer non-support, school attachment, inattention problems, and academic achievement. Multivariate path analyses were conducted to test direct and mediation effects in the over-all model and to explore gender differences. The results provided support for the hypothesized model indicating that the relationship between peer victimization and school attachment is mediated by perceived peer non-support, and that school attachment is related to inattentive school behaviors and poor academic achievement. Paths indicated invariance across models for gender. Prevention and intervention implications of these findings are discussed.

Work-family Conflict and Alcohol Use: Examination of a Moderated Mediation Model

PubMed Central

Wolff, Jennifer M.; Rospenda, Kathleen M.; Richman, Judith A.; Liu, Li; Milner, Lauren A.

2013-01-01

Research consistently documents the negative effects of work-family conflict; however, little focuses on alcohol use. This study embraces a tension-reduction theory of drinking, wherein alcohol use is thought to reduce the negative effects of stress. The purpose of the present study was to test a moderated mediation model of the relationship between work-family conflict and alcohol use in a Chicagoland community sample of 998 caregivers. Structural equation models showed that distress mediated the relationship between work-family conflict and alcohol use. Furthermore, tension reduction expectancies of alcohol exacerbated the relationship between distress and alcohol use. The results advance the study of work-family conflict and alcohol use, helping explain this complicated relationship using sophisticated statistical techniques. Implications for theory and practice are discussed. PMID:23480251

Work-family conflict and alcohol use: examination of a moderated mediation model.

PubMed

Wolff, Jennifer M; Rospenda, Kathleen M; Richman, Judith A; Liu, Li; Milner, Lauren A

2013-01-01

Research consistently documents the negative effects of work-family conflict; however, little research focuses on alcohol use. This study embraces a tension reduction theory of drinking, wherein alcohol use is thought to reduce the negative effects of stress. The purpose of the study was to test a moderated mediation model of the relationship between work-family conflict and alcohol use in a Chicagoland community sample of 998 caregivers. Structural equation models showed that distress mediated the relationship between work-family conflict and alcohol use. Furthermore, tension reduction expectancies of alcohol exacerbated the relationship between distress and alcohol use. The results advance the study of work-family conflict and alcohol use, helping explain this complicated relationship using sophisticated statistical techniques. Implications for theory and practice are discussed.

Socioeconomic Attainment of Extremely Low Birth Weight Survivors: The Role of Early Cognition.

PubMed

Dobson, Kathleen G; Ferro, Mark A; Boyle, Michael H; Schmidt, Louis A; Saigal, Saroj; Van Lieshout, Ryan J

2017-03-01

To determine: (1) if childhood cognitive and academic abilities mediate the association between being born at extremely low birth weight (ELBW) and socioeconomic attainment at age 29 to 36 years; (2) which cognitive abilities (IQ, verbal abilities, fluid intelligence, mathematical abilities, or academic achievement) most strongly mediate this association; and (3) if the mediating role of cognition is different in ELBW survivors with significant neurosensory impairment (NSI). A prospective, longitudinal cohort of 100 Canadian ELBW survivors born between 1977 and 1982 and 89 normal birth weight comparison participants were used to examine the mediating role of childhood cognition by using 5 cognitive mediators assessed at age 8 years (overall IQ, verbal IQ, performance IQ, quantitative ability, and academic achievement) on socioeconomic attainment at adulthood. Socioeconomic attainment was defined as personal annual earnings and full-time employment assessed via self-report at age 29 to 36 years. Mediation models revealed that childhood cognition mediated the association between ELBW status and income attainment, with mathematical abilities and overall IQ each accounting for 26% of the direct effect. Mediated effects were not statistically significant in full-time employment models. For both outcomes, the mediating effect of cognition was stronger for ELBW survivors with NSI. Childhood cognitive abilities partially mediate associations between ELBW status and adult income attainment. Early life cognition is a critical predictor of socioeconomic attainment in ELBW survivors, particularly in those born with NSI. Interventions aimed at enhancing early cognition in ELBW survivors may help optimize their later socioeconomic attainment. Copyright © 2017 by the American Academy of Pediatrics.

Role of TLR4 signaling in the nephrotoxicity of heme and heme proteins.

PubMed

Nath, Karl A; Belcher, John D; Nath, Meryl C; Grande, Joseph P; Croatt, Anthony J; Ackerman, Allan W; Katusic, Zvonimir S; Vercellotti, Gregory M

2018-05-01

Destabilized heme proteins release heme, and free heme is toxic. Heme is now recognized as an agonist for the Toll-like receptor-4 (TLR4) receptor. This study examined whether the TLR4 receptor mediates the nephrotoxicity of heme, specifically, the effects of heme on renal blood flow and inflammatory responses. We blocked TLR4 signaling by the specific antagonist TAK-242. Intravenous administration of heme to mice promptly reduced renal blood flow, an effect attenuated by TAK-242. In vitro, TAK-242 reduced heme-elicited activation of NF-κB and its downstream gene monocyte chemoattractant protein-1(MCP-1); in contrast, TAK-242 failed to reduce heme-induced activation of the anti-inflammatory transcription factor Nrf2 and its downstream gene heme oxygenase-1 (HO-1). TAK-242 did not reduce heme-induced renal MCP-1 upregulation in vivo. TAK-242 did not reduce dysfunction and histological injury in the glycerol model of heme protein-induced acute kidney injury (AKI), findings corroborated by studies in TLR4 +/+ and TLR4 -/- mice. We conclude that 1) acute heme-mediated renal vasoconstriction occurs through TLR4 signaling; 2) proinflammatory effects of heme in renal epithelial cells involve TLR4 signaling, whereas the anti-inflammatory effects of heme do not; 3) TLR4 signaling does not mediate the proinflammatory effects of heme in the kidney; and 4) major mechanisms underlying glycerol-induced, heme protein-mediated AKI do not involve TLR4 signaling. These findings in the glycerol model are in stark contrast with findings in virtually all other AKI models studied to date and emphasize the importance of TLR4-independent pathways of heme protein-mediated injury in this model. Finally, these studies urge caution when using observations derived in vitro to predict what occurs in vivo.

Mediators and moderators of long-term effects of violent video games on aggressive behavior: practice, thinking, and action.

PubMed

Gentile, Douglas A; Li, Dongdong; Khoo, Angeline; Prot, Sara; Anderson, Craig A

2014-05-01

Although several longitudinal studies have demonstrated an effect of violent video game play on later aggressive behavior, little is known about the psychological mediators and moderators of the effect. To determine whether cognitive and/or emotional variables mediate the effect of violent video game play on aggression and whether the effect is moderated by age, sex, prior aggressiveness, or parental monitoring. Three-year longitudinal panel study. A total of 3034 children and adolescents from 6 primary and 6 secondary schools in Singapore (73% male) were surveyed annually. Children were eligible for inclusion if they attended one of the 12 selected schools, 3 of which were boys' schools. At the beginning of the study, participants were in third, fourth, seventh, and eighth grades, with a mean (SD) age of 11.2 (2.1) years (range, 8-17 years). Study participation was 99% in year 1. The final outcome measure was aggressive behavior, with aggressive cognitions (normative beliefs about aggression, hostile attribution bias, aggressive fantasizing) and empathy as potential mediators. Longitudinal latent growth curve modeling demonstrated that the effects of violent video game play are mediated primarily by aggressive cognitions. This effect is not moderated by sex, prior aggressiveness, or parental monitoring and is only slightly moderated by age, as younger children had a larger increase in initial aggressive cognition related to initial violent game play at the beginning of the study than older children. Model fit was excellent for all models. Given that more than 90% of youths play video games, understanding the psychological mechanisms by which they can influence behaviors is important for parents and pediatricians and for designing interventions to enhance or mitigate the effects.

Family income, parental education and internalizing and externalizing psychopathology among 2-3-year-old Chinese children: the mediator effect of parent-child conflict.

PubMed

Zhang, Xiao

2014-02-01

Using a sample of 156 Chinese children aged 2-3 years and their parents, this study examined the effects of socio-economic status, specifically family income and parental education, on the children's internalizing and externalizing psychopathology and whether these effects were mediated by mother-child and father-child conflict. Results indicated that family income, maternal education and paternal education all negatively predicted externalizing symptoms. Income also negatively predicted internalizing symptoms among boys but not girls. Maternal education negatively predicted internalizing symptoms among girls but not boys. The effects of income on psychopathology were fully mediated by mother-child and father-child conflict. In contrast, the effects of education were not mediated or only partially mediated by conflict. Findings are discussed in the framework of the family stress model. © 2013 International Union of Psychological Science.

Teachers' Organizational Commitment: Examining the Mediating Effects of Distributed Leadership

ERIC Educational Resources Information Center

Devos, Geert; Tuytens, Melissa; Hulpia, Hester

2014-01-01

This study examines the relation between principals' leadership and teachers' organizational commitment, mediated by distributed leadership. Data were collected from 1,495 teachers in 46 secondary schools. Structural equation modeling indicated that the effect of principals' leadership on teachers' organizational commitment is…

Personality predictors of the development of elementary school children's intentions to drink alcohol: the mediating effects of attitudes and subjective norms.

PubMed

Hampson, Sarah E; Andrews, Judy A; Barckley, Maureen; Severson, Herbert H

2006-09-01

The authors tested a mediation model in which childhood hostility and sociability were expected to influence the development of intentions to use alcohol in the future through the mediating mechanisms of developing attitudes and norms. Children in 1st through 5th grades (N=1,049) from a western Oregon community participated in a longitudinal study involving 4 annual assessments. Hostility and sociability were assessed by teachers' ratings at the 1st assessment, and attitudes, subjective norms, and intentions were assessed by self-report at all 4 assessments. For both genders, latent growth modeling demonstrated that sociability predicted an increase in intentions to use alcohol over time, whereas hostility predicted initial levels of these intentions. These personality effects were mediated by the development of attitudes and subjective norms, supporting a model wherein childhood personality traits exert their influence on the development of intentions to use alcohol through the development of these more proximal cognitions. ((c) 2006 APA, all rights reserved).

The Relationship between Job Demands and Employees' Counterproductive Work Behaviors: The Mediating Effect of Psychological Detachment and Job Anxiety.

PubMed

Chen, Yang; Li, Shuang; Xia, Qing; He, Chao

2017-01-01

This study aims to explore the relation between job demands and counterproductive work behaviors (CWBs). A cross-sectional sample of 439 coal miners completed a self-report questionnaire that assessed their job demands, psychological detachment, job anxiety, and CWBs in a Chinese context. The conceptual model, based on the stressor-detachment model, was examined using structural equation modeling. The results suggest that psychological detachment mediates not only the relation between job demands and job anxiety but also that between job demands and CWBs. Furthermore, the relation between job demands and CWBs is sequentially mediated by psychological detachment and job anxiety. Our findings validate the effectiveness of the stressor-detachment model. Moreover, we demonstrate that the underlying mechanism of the relation between job demands and CWBs can be explained by psychological detachment and job anxiety.

The Relationship between Job Demands and Employees’ Counterproductive Work Behaviors: The Mediating Effect of Psychological Detachment and Job Anxiety

PubMed Central

Chen, Yang; Li, Shuang; Xia, Qing; He, Chao

2017-01-01

This study aims to explore the relation between job demands and counterproductive work behaviors (CWBs). A cross-sectional sample of 439 coal miners completed a self-report questionnaire that assessed their job demands, psychological detachment, job anxiety, and CWBs in a Chinese context. The conceptual model, based on the stressor-detachment model, was examined using structural equation modeling. The results suggest that psychological detachment mediates not only the relation between job demands and job anxiety but also that between job demands and CWBs. Furthermore, the relation between job demands and CWBs is sequentially mediated by psychological detachment and job anxiety. Our findings validate the effectiveness of the stressor-detachment model. Moreover, we demonstrate that the underlying mechanism of the relation between job demands and CWBs can be explained by psychological detachment and job anxiety. PMID:29163274

Explaining academic-track boys' underachievement in language grades: Not a lack of aptitude but students' motivational beliefs and parents' perceptions?

PubMed

Heyder, Anke; Kessels, Ursula; Steinmayr, Ricarda

2017-06-01

Boys earn lower grades in languages than girls. The expectancy-value model by Eccles et al. (, A series of books in psychology. Achievement and achievement motives. Psychological and sociological approaches, W.H. Freeman, San Francisco, CA, 76) is a comprehensive theoretical model for explaining gender differences in educational outcomes. In the past, most studies have focused on girls' disadvantage in math and science and on the role of the students' motivational beliefs. We aimed to explain boys' lower language grades by applying the expectancy-value model while taking into account students' motivational beliefs as well as their aptitude, prior achievement, and socializers' beliefs. In addition, we aimed at exploring the incremental contribution of each potential mediator. Five hundred and twenty German students (age M = 17 years; 58% female) and 374 parents (age M = 47 years). Student-reported ability self-concept (ASC) and task values, parents' perceptions of students' ability, students' prior achievement as reported by schools, and students' verbal intelligence test scores were all tested as mediators of the effect of gender on grades in German while controlling for parents' socioeconomic status. Single-mediator models and a multiple-mediator model were estimated using structural equation modelling. All variables proved to be relevant for explaining boys' underachievement in language grades. Whereas students' ASC, task values, prior achievement, and parents' perceptions mediated the gender effect, verbal intelligence was identified as a suppressor variable increasing the gender effect. Our results challenge the stereotypic belief that boys' lower grades are due to lower verbal aptitude. Rather, students' motivational beliefs and parents' perceptions seem critical factors. Implications for both future research and practice are discussed. © 2017 The British Psychological Society.

Parenting of divorced mothers as a link between social status and boys' academic outcomes: unpacking the effects of socioeconomic status.

PubMed

DeGarmo, D S; Forgatch, M S; Martinez, C R

1999-01-01

Socialization theories posit parenting practices as mechanisms linking socioeconomic status (SES) and children's academic outcomes. A mediational parenting model was tested examining separate effects of maternal education, occupation, and income for a sample of 238 divorced or recently separated mothers of 6- to 9-year-old sons. For the SEM path models, each indicator of SES was associated with better parenting, and parenting in turn had indirect effects on achievement through home skill-building activities and school behavior. The direct effect of maternal education on achievement was mediated by home skill-building activities, the direct effect of maternal occupation on achievement was not mediated, and income measures had no direct effects on achievement. These findings underscore the importance of unpacking the effects of SES and the relevance of effective parenting practices as a protective factor in the home and school environment for young boys' school success during postdivorce adjustment.

Urban residential greenspace and mental health in youth: Different approaches to testing multiple pathways yield different conclusions.

PubMed

Dzhambov, Angel; Hartig, Terry; Markevych, Iana; Tilov, Boris; Dimitrova, Donka

2018-01-01

Urban greenspace can benefit mental health through multiple mechanisms. They may work together, but previous studies have treated them as independent. We aimed to compare single and parallel mediation models, which estimate the independent contributions of different paths, to several models that posit serial mediation components in the pathway from greenspace to mental health. We collected cross-sectional survey data from 399 participants (15-25 years of age) in the city of Plovdiv, Bulgaria. Objective "exposure" to urban residential greenspace was defined by the Normalized Difference Vegetation Index (NDVI), Soil Adjusted Vegetation Index, tree cover density within the 500-m buffer, and Euclidean distance to the nearest urban greenspace. Self-reported measures of availability, access, quality, and usage of greenspace were also used. Mental health was measured with the General Health Questionnaire. The following potential mediators were considered in single and parallel mediation models: restorative quality of the neighborhood, neighborhood social cohesion, commuting and leisure time physical activity, road traffic noise annoyance, and perceived air pollution. Four models were tested with the following serial mediation components: (1) restorative quality → social cohesion; (2) restorative quality → physical activity; (3) perceived traffic pollution → restorative quality; (4) and noise annoyance → physical activity. There was no direct association between objectively-measured greenspace and mental health. For the 500-m buffer, the tests of the single mediator models suggested that restorative quality mediated the relationship between NDVI and mental health. Tests of parallel mediation models did not find any significant indirect effects. In line with theory, tests of the serial mediation models showed that higher restorative quality was associated with more physical activity and more social cohesion, and in turn with better mental health. As for self-reported greenspace measures, single mediation through restorative quality was significant only for time in greenspace, and there was no mediation though restorative quality in the parallel mediation models; however, serial mediation through restorative quality and social cohesion/physical activity was indicated for all self-reported measures except for greenspace quality. Statistical models should adequately address the theoretically indicated interdependencies between mechanisms underlying association between greenspace and mental health. If such causal relationships hold, testing mediators alone or in parallel may lead to incorrect inferences about the relative contribution of specific paths, and thus to inappropriate intervention strategies. Copyright © 2017 Elsevier Inc. All rights reserved.

Acculturation, Social Self-Control, and Substance Use Among Hispanic Adolescents

PubMed Central

Pokhrel, Pallav; Herzog, Thaddeus A.; Sun, Ping; Rohrbach, Louise A.; Sussman, Steve

2014-01-01

It is unclear how acculturation is related to self-control characteristics and whether part of the effect of acculturation on Hispanic adolescents’ substance use behavior is mediated through lower self-control. We tested social self-control, peer substance use, and baseline substance use as mediators of the effect of Hispanic (predominantly Mexican or Mexican American) adolescents’ level of U.S. acculturation on their substance use behavior 1 year later. In addition, we tested gender as a possible moderator of the pathways involved in the mediation model. Participants included 1,040 self-identified Hispanic/Latino adolescents (M = 14.7; SD = 0.90; 89% Mexican/Mexican American) recruited from nine public high schools. Acculturation was measured in terms of adolescents’ extent of English language use in general, at home, with friends, and their use of the English-language entertainment media. Analyses were conducted using structural equation modeling and controlled for potential confounders such as age and parental education. Results indicated a statistically significant three-path mediation in which poor social self-control and peer substance use mediated the effects of acculturation on prospective substance use. Paths in the mediation model were not found to differ by gender. Our findings suggest that acculturation may influence adolescents’ self-control characteristics related to interpersonal functioning, which may in turn influence their affiliation with substance-using friends and substance use behavior. Implications of the findings are discussed in terms of future research and prevention programming. PMID:23772765

Team performance in the Italian NHS: the role of reflexivity.

PubMed

Urbini, Flavio; Callea, Antonino; Chirumbolo, Antonio; Talamo, Alessandra; Ingusci, Emanuela; Ciavolino, Enrico

2018-04-09

Purpose The purpose of this paper is twofold: first, to investigate the goodness of the input-process-output (IPO) model in order to evaluate work team performance within the Italian National Health Care System (NHS); and second, to test the mediating role of reflexivity as an overarching process factor between input and output. Design/methodology/approach The Italian version of the Aston Team Performance Inventory was administered to 351 employees working in teams in the Italian NHS. Mediation analyses with latent variables were performed via structural equation modeling (SEM); the significance of total, direct, and indirect effect was tested via bootstrapping. Findings Underpinned by the IPO framework, the results of SEM supported mediational hypotheses. First, the application of the IPO model in the Italian NHS showed adequate fit indices, showing that the process mediates the relationship between input and output factors. Second, reflexivity mediated the relationship between input and output, influencing some aspects of team performance. Practical implications The results provide useful information for HRM policies improving process dimensions of the IPO model via the mediating role of reflexivity as a key role in team performance. Originality/value This study is one of a limited number of studies that applied the IPO model in the Italian NHS. Moreover, no study has yet examined the role of reflexivity as a mediator between input and output factors in the IPO model.

Transforming Environmental Knowledge into Behavior: The Mediating Role of Environmental Emotions

ERIC Educational Resources Information Center

Carmi, Nurit; Arnon, Sara; Orion, Nir

2015-01-01

The present study was based on the premise that environmental knowledge can drive environmental behavior only if it arouses environmental emotions. Using a structural equations modeling approach, we tested the direct, as well as the indirect (mediated) effects of knowledge on behavior and assessed the mediating role of environmental emotions. We…

A General Multilevel SEM Framework for Assessing Multilevel Mediation

ERIC Educational Resources Information Center

Preacher, Kristopher J.; Zyphur, Michael J.; Zhang, Zhen

2010-01-01

Several methods for testing mediation hypotheses with 2-level nested data have been proposed by researchers using a multilevel modeling (MLM) paradigm. However, these MLM approaches do not accommodate mediation pathways with Level-2 outcomes and may produce conflated estimates of between- and within-level components of indirect effects. Moreover,…

Finding Positive Meaning after Loss: The Mediating Role of Reflection for Bereaved Individuals

ERIC Educational Resources Information Center

Boyraz, Guler; Horne, Sharon G.; Sayger, Thomas V.

2010-01-01

This study examined the mediating effect of reflection on the relationship between search for meaning, positive affect, negative affect, and positive meaning-finding among 380 bereaved individuals. Using structural equation modeling, reflection was found to mediate the relationship between search for meaning, affect (positive and negative), and…

Identity as a Moderator and Mediator of Communication Effects: Evidence and Implications for Message Design.

PubMed

Comello, Maria Leonora G; Farman, Lisa

2016-10-02

Advertisements, movies, and other forms of media content have potential to change behaviors and antecedent psychological states by appealing to identity. However, the mechanisms that are responsible for persuasive effects of such content have not been adequately specified. A recently proposed model of communication effects (the prism model) advances the study of mechanisms and argues that identity can serve as both a moderator and mediator of communication effects on behavior-relevant outcomes. These intervening roles are made possible by the complex nature of identity (including multiple self-concepts and sensitivity to cues) and messages that cue the importance of and activate particular self-concepts. This article builds on development of the model by presenting empirical support based on re-analysis of an experiment in which participants viewed either a more-stigmatizing or less-stigmatizing portrayal of a recovering drug addict. In line with the model's propositions, exposure to the less-stigmatizing condition led to increases in perspective taking which then led to more acceptance (mediation by identity), while level of perspective taking also changed the effect of condition on acceptance (moderation by identity). These results provide support for the model's proposition of simultaneous intervening roles. The authors discuss implications for strategic communication research and practice.

Does Positivity Mediate the Relation of Extraversion and Neuroticism with Subjective Happiness?

PubMed Central

Lauriola, Marco; Iani, Luca

2015-01-01

Recent theories suggest an important role of neuroticism, extraversion, attitudes, and global positive orientations as predictors of subjective happiness. We examined whether positivity mediates the hypothesized relations in a community sample of 504 adults between the ages of 20 and 60 years old (females = 50%). A model with significant paths from neuroticism to subjective happiness, from extraversion and neuroticism to positivity, and from positivity to subjective happiness fitted the data (Satorra–Bentler scaled chi-square (38) = 105.91; Comparative Fit Index = .96; Non-Normed Fit Index = .95; Root Mean Square Error of Approximation = .060; 90% confidence interval = .046, .073). The percentage of subjective happiness variance accounted for by personality traits was only about 48%, whereas adding positivity as a mediating factor increased the explained amount of subjective happiness to 78%. The mediation model was invariant by age and gender. The results show that the effect of extraversion on happiness was fully mediated by positivity, whereas the effect of neuroticism was only partially mediated. Implications for happiness studies are also discussed. PMID:25781887

Verbal and Visual Memory Impairments in Bipolar I and II Disorder.

PubMed

Ha, Tae Hyon; Kim, Ji Sun; Chang, Jae Seung; Oh, Sung Hee; Her, Ju Young; Cho, Hyun Sang; Park, Tae Sung; Shin, Soon Young; Ha, Kyooseob

2012-12-01

To compare verbal and visual memory performances between patients with bipolar I disorder (BD I) and patients with bipolar II disorder (BD II) and to determine whether memory deficits were mediated by impaired organizational strategies. Performances on the Korean-California Verbal Learning Test (K-CVLT) and the Rey-Osterrieth Complex Figure Test (ROCF) in 37 patients with BD I, 46 patients with BD II and 42 healthy subjects were compared. Mediating effects of impaired organization strategies on poor delayed recall was tested by comparing direct and mediated models using multiple regression analysis. Both patients groups recalled fewer words and figure components and showed lower Semantic Clustering compared to controls. Verbal memory impairment was partly mediated by difficulties in Semantic Clustering in both subtypes, whereas the mediating effect of Organization deficit on the visual memory impairment was present only in BD I. In all mediated models, group differences in delayed recall remained significant. Our findings suggest that memory impairment may be one of the fundamental cognitive deficits in bipolar disorders and that executive dysfunctions can exert an additional influence on memory impairments.

Transdiagnostic mechanisms in depression and anxiety: The role of rumination and attentional control.

PubMed

Hsu, Kean J; Beard, Courtney; Rifkin, Lara; Dillon, Daniel G; Pizzagalli, Diego A; Björgvinsson, Thröstur

2015-12-01

Deficits in attentional control have been hypothesized to cause rumination, suggesting that the relationships between attentional control and clinical symptoms may be mediated in part by rumination. However, to date, no clinical study has examined these constructs transdiagnostically in a path analysis model. Fifty-one adults presenting for treatment completed measures of self-reported attentional control, rumination, and depression and anxiety symptoms. A bias-corrected path analysis-based approach was employed to test whether indirect (i.e., mediating) effects of rumination were significantly associated with the direct effects of attentional control on depression and anxiety symptoms. Separate models for depression and anxiety symptoms were tested along with reverse models using attentional control as a proposed mediator. The relationship between attentional control and clinical symptomatology (i.e., both depression and anxiety symptoms) was mediated by rumination. Poor attentional control was associated with more rumination and consequently more severe symptoms of depression and anxiety. The reverse relationship (i.e., attentional control mediating the relationship between rumination and depression or anxiety symptoms) was not significant. Study design did not allow testing of temporal precedence for the mediation models. All constructs were assessed via self-report. Attentional control appears to impact depression and anxiety symptoms through rumination. The pathway between poor attentional control and emotion dysregulation via rumination suggests that interventions targeting attentional control may decrease maladaptive ruminative processes, leading to improved emotion regulation and reduced clinical symptomatology. Future studies should examine the stability of this mediational relationship over time (and in the face of targeted interventions). Copyright © 2015 Elsevier B.V. All rights reserved.

Motivations for Social Media Use and Impact on Political Participation in China: A Cognitive and Communication Mediation Approach.

PubMed

Chen, Zhuo; Chan, Michael

2017-02-01

Integrating uses and gratifications theory and the cognitive/communication mediation model: this study examines Chinese students' use of social media and subsequent impact on political participation. An integrative framework is proposed where media use, political expression, and political cognitions (efficacy and knowledge) play important mediating roles between audience motivations and participation. Structural equation analyses showed support for the integrated model. Guidance and social utility motivations exhibited different indirect effects on online and offline participation through social media news, discussion, and political efficacy. Entertainment motivations exhibited no direct or indirect effects. Contrary to expectations and previous literature, surveillance motivations exhibited negative direct and indirect effects on offline participation, which may be attributed to the particular Chinese social and political context. Implications of the findings are discussed.

Predictors of self-perceived cultural competence among children's mental health providers.

PubMed

Keyser, Victoria; Gamst, Glenn; Meyers, Lawrence S; Der-Karabetian, Aghop; Morrow, Gloria

2014-07-01

Based on empirical research and predictions from the Multicultural Assessment-Intervention Process model, the racial attitudes, ethnic identity, and acculturation of a national sample of 371 child mental health service providers were assessed as possible predictors of practitioner self-perceived cultural competence. It was hypothesized that ethnic identity and racial attitudes would each directly affect self-perceived cultural competence and that acculturation and racial attitudes would mediate the effect of ethnic identity. The results indicated that ethnic identity exerted a direct effect on self-perceived cultural competence and that this effect was partially mediated by respondents' racial attitudes; however, acculturation had no significant role as a mediator. The results are discussed within the context of the Multicultural Assessment-Intervention Process model and implications for providing culturally competent services to children.

MEDIATION EFFECTS OF OVERCOMMITMENT ON EFFORT, REWARD, INSOMNIA, AND WELL-BEING AS MODERATED BY GENDER, AGE, AND JOB POSITION.

PubMed

Chao, Wang; Shuang, Li; Tao, Li; Shanfa, Yu; Junming, Dai

2017-01-01

This study aimed to detect the mediation effect of over-commitment between occupational stress, insomnia, and well-being; and the moderating role of gender, age and job position are also to be analyzed. One thousand six hundred eighteen valid samples were recruited from electronic manufacturing service industry in Hunan Province, China. All the data were collected by selfrated questionnaires after written consent. This paper introduced Effort-Reward- Insomnia-Well-being model, and it was fitted and validated through the structural equation model analysis. The results of single factor correlation analysis indicated that the coefficients between most of the items and dimensions presented statistical significance. The final fitting model had satisfactory global goodness of fit (CMIN/DF=3.99, AGFI=0.926, NNFI=0.950, IFI=0.956, RMSEA=0.043). Both of the measurement model and structural model had acceptable path loadings. Effort associated with insomnia indirectly and related to well-being directly and indirectly; reward could have either directly associated with insomnia and well-being, or indirectly related to them through over-commitment. Covariates as gender, age and position made differences on the association between occupational stress and health outcomes. Over-commitment had the ability to mediate the relationships between effort, reward, and health outcomes, and mediation effect varied from different working conditions and outcomes under different covariates.

Causal mediation analysis with a binary outcome and multiple continuous or ordinal mediators: Simulations and application to an alcohol intervention

PubMed Central

Nguyen, Trang Quynh; Webb-Vargas, Yenny; Koning, Ina M.; Stuart, Elizabeth A.

2016-01-01

We investigate a method to estimate the combined effect of multiple continuous/ordinal mediators on a binary outcome: 1) fit a structural equation model with probit link for the outcome and identity/probit link for continuous/ordinal mediators, 2) predict potential outcome probabilities, and 3) compute natural direct and indirect effects. Step 2 involves rescaling the latent continuous variable underlying the outcome to address residual mediator variance/covariance. We evaluate the estimation of risk-difference- and risk-ratio-based effects (RDs, RRs) using the ML, WLSMV and Bayes estimators in Mplus. Across most variations in path-coefficient and mediator-residual-correlation signs and strengths, and confounding situations investigated, the method performs well with all estimators, but favors ML/WLSMV for RDs with continuous mediators, and Bayes for RRs with ordinal mediators. Bayes outperforms WLSMV/ML regardless of mediator type when estimating RRs with small potential outcome probabilities and in two other special cases. An adolescent alcohol prevention study is used for illustration. PMID:27158217

Effects of compassion meditation on a psychological model of charitable donation.

PubMed

Ashar, Yoni K; Andrews-Hanna, Jessica R; Yarkoni, Tal; Sills, Jenifer; Halifax, Joan; Dimidjian, Sona; Wager, Tor D

2016-08-01

Compassion is critical for societal wellbeing. Yet, it remains unclear how specific thoughts and feelings motivate compassionate behavior, and we lack a scientific understanding of how to effectively cultivate compassion. Here, we conducted 2 studies designed to a) develop a psychological model predicting compassionate behavior, and b) test this model as a mediator of a Compassion Meditation (CM) intervention and identify the "active ingredients" of CM. In Study 1, we developed a model predicting compassionate behavior, operationalized as real-money charitable donation, from a linear combination of self-reported tenderness, personal distress, perceived blamelessness, and perceived instrumental value of helping with high cross-validated accuracy, r = .67, p < .0001. Perceived similarity to suffering others did not predict charitable donation when controlling for other feelings and attributions. In Study 2, a randomized controlled trial, we tested the Study 1 model as a mediator of CM and investigated active ingredients. We compared a smartphone-based CM program to 2 conditions-placebo oxytocin and a Familiarity intervention-to control for expectancy effects, demand characteristics, and familiarity effects. Relative to control conditions, CM increased charitable donations, and changes in the Study 1 model of feelings and attributions mediated this effect (pab = .002). The Familiarity intervention led to decreases in primary outcomes, while placebo oxytocin had no significant effects on primary outcomes. Overall, this work contributes a quantitative model of compassionate behavior, and informs our understanding of the change processes and intervention components of CM. (PsycINFO Database Record (c) 2016 APA, all rights reserved).

Examining an Elaborated Sociocultural Model of Disordered Eating Among College Women: The Roles of Social Comparison and Body Surveillance

PubMed Central

Fitzsimmons-Craft, Ellen E.; Bardone-Cone, Anna M.; Bulik, Cynthia M.; Wonderlich, Stephen A.; Crosby, Ross D.; Engel, Scott G.

2014-01-01

Social comparison (i.e., body, eating, exercise) and body surveillance were tested as mediators of the thin-ideal internalization-body dissatisfaction relationship in the context of an elaborated sociocultural model of disordered eating. Participants were 219 college women who completed two questionnaire sessions 3 months apart. The cross-sectional elaborated sociocultural model (i.e., including social comparison and body surveillance as mediators of the thin-ideal internalization-body dissatisfaction relation) provided a good fit to the data, and the total indirect effect from thin-ideal internalization to body dissatisfaction through the mediators was significant. Social comparison emerged as a significant specific mediator while body surveillance did not. The mediation model did not hold prospectively; however, social comparison accounted for unique variance in body dissatisfaction and disordered eating 3 months later. Results suggest that thin-ideal internalization may not be “automatically” associated with body dissatisfaction and that it may be especially important to target comparison in prevention and intervention efforts. PMID:25160010

Promoting Teachers' Implementation of Classroom-Based Prevention Programming Through Coaching: The Mediating Role of the Coach-Teacher Relationship.

PubMed

Johnson, Stacy R; Pas, Elise T; Bradshaw, Catherine P; Ialongo, Nicholas S

2018-05-01

There is growing awareness of the importance of implementation fidelity and the supports, such as coaching, to optimize it. This study examined how coaching activities (i.e., check-ins, needs assessment, modeling, and technical assistance) related directly and indirectly to implementation dosage and quality of the PAX Good Behavior Game, via a mediating pathway through working relationship. Mediation analyses of 138 teachers revealed direct effects of modeling and working relationship on implementation dosage, whereas needs assessment was associated with greater dosage indirectly, by higher ratings of the working relationship. Understanding how coaching activities promote implementation fidelity elements has implications for improving program effectiveness.

A novel measure of effect size for mediation analysis.

PubMed

Lachowicz, Mark J; Preacher, Kristopher J; Kelley, Ken

2018-06-01

Mediation analysis has become one of the most popular statistical methods in the social sciences. However, many currently available effect size measures for mediation have limitations that restrict their use to specific mediation models. In this article, we develop a measure of effect size that addresses these limitations. We show how modification of a currently existing effect size measure results in a novel effect size measure with many desirable properties. We also derive an expression for the bias of the sample estimator for the proposed effect size measure and propose an adjusted version of the estimator. We present a Monte Carlo simulation study conducted to examine the finite sampling properties of the adjusted and unadjusted estimators, which shows that the adjusted estimator is effective at recovering the true value it estimates. Finally, we demonstrate the use of the effect size measure with an empirical example. We provide freely available software so that researchers can immediately implement the methods we discuss. Our developments here extend the existing literature on effect sizes and mediation by developing a potentially useful method of communicating the magnitude of mediation. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

[Effect of Adolescents' Abuse Experience on Suicidal Ideation: Focused on Moderated Mediation Effect of Self-esteem on Depression and Anxiety].

PubMed

Kim, Ji Young; Lee, Kyunghee

2015-10-01

The purpose of this study was to examine the moderating mediation effect of self-esteem on the relations among adolescents' abuse experiences, depression and anxiety, and suicidal ideation. The participants were selected using secondary data from a population in the 2012 Korea Welfare Panel Survey (KOWEPS). Data were analyzed using SPSS 15.0 and SPSS Macro, and bootstrapping and hierarchical regression analysis were performed to analyze multilevel models. First, analysis of the mediating effect of the adolescents' abuse showed that there was significant mediating influence between suicidal ideation and depression and anxiety. Second, hierarchical regression analysis showed that self-esteem had significant mediation effect on depression and anxiety in adolescents' suicidal ideation. Third, SPSS Macro showed that self-esteem also significantly moderated the mediating effect of adolescents' abuse experiences on suicidal ideation through depression and anxiety. The study results suggest that in future research on adolescent's abuse experience, the risk of suicide in depression and anxiety scores should be selected through evaluation of each individual's self-esteem scale. Coping strategies with immediate early intervention should be suggested.

Mediators of a brief hypnosis intervention to control side effects in breast surgery patients: Response expectancies and emotional distress

PubMed Central

Montgomery, Guy H.; Hallquist, Michael N.; Schnur, Julie B.; David, Daniel; Silverstein, Jeffrey H.; Bovbjerg, Dana H.

2010-01-01

Hypnosis is widely recognized as an empirically supported intervention to improve postsurgical outcomes. However, to date, no research has examined mediators of hypnotic benefit among surgery patients. The present study was designed to test the hypotheses that response expectancies and emotional distress would mediate the effects of an empirically validated presurgical hypnosis intervention on postsurgical side effects (i.e., pain, nausea, and fatigue). In a sample of 200 women undergoing breast conserving surgery (mean age = 48.50 years), structural equation modeling revealed the following: 1) hypnotic effects on postsurgical pain were partially mediated by pain expectancy (p< .0001), but not by distress (p=.12); 2) hypnotic effects on postsurgical nausea were partially mediated by presurgical distress (p=.02), but not by nausea expectancy (p=.10); 3) hypnotic effects on postsurgical fatigue were partially mediated by both fatigue expectancy (p=.0001) and presurgical distress (p=.02). These results improve understanding of the underlying mechanisms responsible for hypnotic phenomena in the surgical setting, and suggest that future hypnotic interventions target patient expectancies and distress to improve postsurgical recovery. PMID:20099953

Paternal Lifestyle-Related Parenting Practices Mediate Changes in Children's Dietary and Physical Activity Behaviors: Findings From the Healthy Dads, Healthy Kids Community Randomized Controlled Trial.

PubMed

Lloyd, Adam B; Lubans, David R; Plotnikoff, Ronald C; Morgan, Philip J

2015-09-01

This study examined potential parenting-related mediators of children's physical activity and dietary behavior change in the Healthy Dads, Healthy Kids (HDHK) community program. A randomized controlled trial was conducted with 45 overweight/obese (mean [SD] age = 39.8 [5.4] years; BMI = 32.4 [3.8]) fathers and their children (n = 77; 58% boys; mean [SD] age = 7.7 [2.5] years). Families were randomized to either the HDHK program or wait-list control group. The program involved 7 sessions. Fathers and their children were assessed at baseline and at 14 weeks for physical activity (pedometery) and core food intake (Questionnaire). Fathers' lifestyle-related parenting practices included; self-efficacy, beliefs, modeling, logistic support, rules, cophysical activity, shared mealtime frequency and intentions. Significant intervention effects were found for cophysical activity and modeling physical activity. Cophysical activity mediated children's physical activity in the intervention ('mediated effect,' AB = 653, 95% CI = 4-2050) and was responsible for 59.5% of the intervention effect. Fathers' beliefs mediated children's percent energy from core foods (AB = 1.51, 95% CI = 0.05-5.55) and accounted for 72.9% of the intervention effect. Participation in the HDHK program positively impacted on fathers' cophysical activity with their child and beliefs about healthy eating which mediated changes in children's diet and physical activity behaviors.

The Mediating Effect of Organizational Trust on the Link between the Areas of Work Life and Emotional Exhaustion

ERIC Educational Resources Information Center

Bayhan Karapinar, Pinar; Metin Camgoz, Selin; Tayfur Ekmekci, Ozge

2016-01-01

The study tests an integrative model that considers the plausible effects of different areas of work life on emotional exhaustion. It also tests the mediating effect of organizational trust on this relationship. More specifically, while perceived incongruence in six areas of work life (workload, fairness, reward, community, control and value) is…

Mediating effects of emotional exhaustion on the relationship between job demand–control model and mental health.

PubMed

Huang, Yu-Hwa; Du, Pey-Ian; Chen, Chin-Hui; Yang, Chin-Ann; Huang, Ing-Chung

2011-04-01

This study attempted to investigate the role of emotional exhaustion as a mediator on the relationship between job demands-control (JDC) model and mental health. Three-wave data from 297 employees were collected. The results showed that job demands were positively related to emotional exhaustion, and increasing job demands will increase the level of emotional exhaustion. Job control was negatively associated with emotional exhaustion; therefore, increasing job control will decrease the level of emotional exhaustion. Emotional exhaustion was negatively related to mental health. Emotional exhaustion fully mediated the relationship between job demands and mental health, and partially mediated the positive relationship between job control and mental health. In addition, job control was positively associated with mental health directly. The remarkable finding of the present study was that emotional exhaustion served as the key mediator between the JDC model and mental health. Theoretical and managerial implications and limitations were discussed.

Dark matter self-interactions from a general spin-0 mediator

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kahlhoefer, Felix; Schmidt-Hoberg, Kai; Wild, Sebastian, E-mail: felix.kahlhoefer@desy.de, E-mail: kai.schmidt-hoberg@desy.de, E-mail: sebastian.wild@desy.de

2017-08-01

Dark matter particles interacting via the exchange of very light spin-0 mediators can have large self-interaction rates and obtain their relic abundance from thermal freeze-out. At the same time, these models face strong bounds from direct and indirect probes of dark matter as well as a number of constraints on the properties of the mediator. We investigate whether these constraints can be consistent with having observable effects from dark matter self-interactions in astrophysical systems. For the case of a mediator with purely scalar couplings we point out the highly relevant impact of low-threshold direct detection experiments like CRESST-II, which essentiallymore » rule out the simplest realization of this model. These constraints can be significantly relaxed if the mediator has CP-violating couplings, but then the model faces strong constraints from CMB measurements, which can only be avoided in special regions of parameter space.« less

Proactive sustainability strategy and corporate sustainability performance: The mediating effect of sustainability control systems.

PubMed

Wijethilake, Chaminda

2017-07-01

This study examines to what extent corporations use sustainability control systems (SCS) to translate proactive sustainability strategy into corporate sustainability performance. The study investigates the mediating effect of SCS on the relationship between proactive sustainability strategy and corporate sustainability performance. Survey data were collected from top managers in 175 multinational and local corporations operating in Sri Lanka and analyzed using Partial Least Squares Structural Equation Modeling (PLS-SEM). SCS were observed to only partially mediate the relationship between proactive sustainability strategy and corporate sustainability performance. The mediating effect of SCS is further examined under three sustainability strategies; environmental and social strategies reveal a partial mediation, while the economic strategy exhibits no mediation. The study also finds that (i) a proactive sustainability strategy is positively associated with SCS and corporate sustainability performance and (ii) SCS are positively associated with corporate sustainability performance. Copyright © 2017 Elsevier Ltd. All rights reserved.

Working Memory and Cognitive Flexibility Mediates Visuoconstructional Abilities in Older Adults with Heterogeneous Cognitive Ability.

PubMed

Ávila, Rafaela T; de Paula, Jonas J; Bicalho, Maria A; Moraes, Edgar N; Nicolato, Rodrigo; Malloy-Diniz, Leandro F; Diniz, Breno S

2015-05-01

Previous studies suggest that executive functions influence the performance on visuoconstructional tasks. This study aims to investigate whether the relationship between planning ability and the copy of complex figures is mediated by distinct components of executive functions (i.e., working memory, inhibitory control and cognitive flexibility). We included a 129 older adults with Alzheimer's disease (n=36, AD), mild cognitive impairment (MCI, n=67), and with no evidence of cognitive impairment (controls, n=26). We evaluated the mediation effect of planning abilities, working memory, cognitive flexibility and inhibitory control on visuoconstructional tasks using a multiple mediation models. We found a significant direct effect of planning on visuoconstructional abilities and a partial mediation effect of working memory and cognitive flexibility on visuoconstructional abilities. The present results indicate that the performance on visuoconstructional task is mediated by multiple interrelated executive functions components, in particular working memory and cognitive flexibility.

Information Processing Versus Social Cognitive Mediators of Weight Loss in a Podcast-Delivered Health Intervention

PubMed Central

Ko, Linda K.; Turner-McGrievy, Gabrielle; Campbell, Marci K.

2016-01-01

Podcasting is an emerging technology, and previous interventions have shown promising results using theory-based podcast for weight loss among overweight and obese individuals. This study investigated whether constructs of social cognitive theory and information processing theories (IPTs) mediate the effect of a podcast intervention on weight loss among overweight individuals. Data are from Pounds off Digitally, a study testing the efficacy of two weight loss podcast interventions (control podcast and theory-based podcast). Path models were constructed (n = 66). The IPTs—elaboration likelihood model, information control theory, and cognitive load theory—mediated the effect of a theory-based podcast on weight loss. The intervention was significantly associated with all IPTs. Information control theory and cognitive load theory were related to elaboration, and elaboration was associated with weight loss. Social cognitive theory constructs did not mediate weight loss. Future podcast interventions grounded in theory may be effective in promoting weight loss. PMID:24082027

Cumulative Risk and Adolescent's Internalizing and Externalizing Problems: The Mediating Roles of Maternal Responsiveness and Self-Regulation

ERIC Educational Resources Information Center

Doan, Stacey N.; Fuller-Rowell, Thomas E.; Evans, Gary W.

2012-01-01

The purpose of the present study was to examine longitudinal associations among maternal responsiveness, self-regulation, and behavioral adjustment in adolescents. The authors used structural equation modeling to test a model that demonstrates that the effects of early cumulative risk on behavioral problems is mediated by maternal responsiveness…

Parental and Peer Support as Predictors of Depression and Self-Esteem among College Students

ERIC Educational Resources Information Center

Li, Susan Tinsley; Albert, Arielle Berman; Dwelle, Deborah G.

2014-01-01

We investigated the relationship between parent support and peer support as predictors of depression and self-esteem in college students. Several competing models of parental and peer influence were compared including a mediational model in which peer support was hypothesized to mediate the effects of parental support on adjustment. The results…

Mental Health, School Problems, and Social Networks: Modeling Urban Adolescent Substance Use

ERIC Educational Resources Information Center

Mason, Michael J.

2010-01-01

This study tested a mediation model of the relationship with school problems, social network quality, and substance use with a primary care sample of 301 urban adolescents. It was theorized that social network quality (level of risk or protection in network) would mediate the effects of school problems, accounting for internalizing problems and…

The Mediating Role of Intercultural Wonderment: Connecting Programmatic Components to Global Outcomes in Study Abroad

ERIC Educational Resources Information Center

Engberg, Mark E.; Jourian, T. J.; Davidson, Lisa M.

2016-01-01

This study examines the mediating role of intercultural wonderment in relation to students' development of a global perspective. We utilize both confirmatory factor analysis and structural equation modeling to validate the intercultural wonderment construct and test the direct and indirect effects of the structural pathways in the model,…

Resampling and Distribution of the Product Methods for Testing Indirect Effects in Complex Models

ERIC Educational Resources Information Center

Williams, Jason; MacKinnon, David P.

2008-01-01

Recent advances in testing mediation have found that certain resampling methods and tests based on the mathematical distribution of 2 normal random variables substantially outperform the traditional "z" test. However, these studies have primarily focused only on models with a single mediator and 2 component paths. To address this limitation, a…

Alternative Methods for Assessing Mediation in Multilevel Data: The Advantages of Multilevel SEM

ERIC Educational Resources Information Center

Preacher, Kristopher J.; Zhang, Zhen; Zyphur, Michael J.

2011-01-01

Multilevel modeling (MLM) is a popular way of assessing mediation effects with clustered data. Two important limitations of this approach have been identified in prior research and a theoretical rationale has been provided for why multilevel structural equation modeling (MSEM) should be preferred. However, to date, no empirical evidence of MSEM's…

Three-Level Models for Indirect Effects in School- and Class-Randomized Experiments in Education

ERIC Educational Resources Information Center

Pituch, Keenan A.; Murphy, Daniel L.; Tate, Richard L.

2009-01-01

Due to the clustered nature of field data, multi-level modeling has become commonly used to analyze data arising from educational field experiments. While recent methodological literature has focused on multi-level mediation analysis, relatively little attention has been devoted to mediation analysis when three levels (e.g., student, class,…

A Mediation Model to Explain the Role of Mathematics Skills and Probabilistic Reasoning on Statistics Achievement

ERIC Educational Resources Information Center

Primi, Caterina; Donati, Maria Anna; Chiesi, Francesca

2016-01-01

Among the wide range of factors related to the acquisition of statistical knowledge, competence in basic mathematics, including basic probability, has received much attention. In this study, a mediation model was estimated to derive the total, direct, and indirect effects of mathematical competence on statistics achievement taking into account…

An Analysis of Computer-Mediated Communication between Middle School Students and Scientist Role Models: A Pilot Study.

ERIC Educational Resources Information Center

Murfin, Brian

1994-01-01

Reports on a study of the effectiveness of computer-mediated communication (CMC) in providing African American and female middle school students with scientist role models. Quantitative and qualitative data gathered by analyzing messages students and scientists posted on a shared electronic bulletin board showed that CMC could be an effective…

Minority stress and college persistence attitudes among African American, Asian American, and Latino students: perception of university environment as a mediator.

PubMed

Wei, Meifen; Ku, Tsun-Yao; Liao, Kelly Yu-Hsin

2011-04-01

We examined whether perception of university environment mediated the association between minority status stress and college persistence attitudes after controlling for perceived general stress. Participants were 160 Asian American, African American, and Latino students who attended a predominantly White university. Results of a path model analysis showed that university environment was a significant mediator for the association between minority status stress and college persistence attitudes. Additionally, minority status stress was distinct from perceived general stress. Finally, the results from a multiple-group comparison indicated that the magnitude of the mediation effect was invariant across Asian American, African American, and Latino college students, thus supporting the generalizability of the mediation model.

Does Competence Mediate the Associations between Puberty and Internalizing or Externalizing Problems in Adolescent Girls

PubMed Central

Negriff, Sonya; Hillman, Jennifer, B.; Dorn, Lorah D.

2011-01-01

Purpose To examine separate mediational models linking a) menarcheal status or b) pubertal timing to internalizing and externalizing problems through competence. Method Cross-sectional analyses of 262 adolescent girls (11–17 years; M=14.93, SD=2.17) enrolled in a longitudinal study examining the association of psychological functioning and smoking with reproductive and bone health. Measures of menarcheal status (pre/post), pubertal timing (early, on-time, or late), internalizing and externalizing behavior, and perceived competence (parent and adolescent report) were obtained. Structural Equation Modeling was used for analyses. Results Perceived competence was found to fully mediate the association between menarcheal status and parent report of internalizing and externalizing problems. For adolescent report, there was a full mediation effect for internalizing problems but a partial mediation effect for externalizing problems. Being menarcheal was related to lower competence which was related to higher internalizing and externalizing problems. Models including pubertal timing were not significant. Conclusions Perceived competence is important in understanding the associations between menarcheal status and internalizing and externalizing problems. Interventions targeting competence, particularly in post-menarcheal girls, may reduce or prevent problem behaviors. PMID:21939864

Successful Aging and Subjective Well-Being Among Oldest-Old Adults

PubMed Central

Cho, Jinmyoung; Martin, Peter; Poon, Leonard W.

2015-01-01

Purpose of the Study: This research integrates successful aging and developmental adaptation models to empirically define the direct and indirect effects of 2 distal (i.e., education and past life experiences) and 5 proximal influences (i.e., physical functioning, cognitive functioning, physical health impairment, social resources, and perceived economic status) on subjective well-being. The proximal influences involved predictors outlined in most extant models of successful aging (e.g., Rowe & Kahn, 1998 [Rowe, J. W., & Kahn, R. L. (1998). Successful aging. New York: Pantheon Books.]). Our model extends such models by including distal impact as well as interactions between distal and proximal impacts. Design and Methods: Data were obtained from 234 centenarians and 72 octogenarians in the Georgia Centenarian Study. Structural equation modeling was conducted with Mplus 6.1. Results: Results showed significant direct effects of physical health impairment and social resources on positive aspects of subjective well-being among oldest-old adults. We also found significant indirect effects of cognitive functioning and education on positive affect among oldest-old adults. Social resources mediated the relationship between cognitive functioning and positive affect; and cognitive functioning and social resources mediated the relationship between education and positive affect. In addition, physical health impairment mediated the relationship between cognitive functioning and positive affect; and cognitive functioning and physical health impairment mediated the relationship between education and positive affect. Implications: Integrating 2 different models (i.e., successful aging and developmental adaptation) provided a comprehensive view of adaptation from a developmental perspective. PMID:25112594

Does Mindfulness Enhance Critical Thinking? Evidence for the Mediating Effects of Executive Functioning in the Relationship between Mindfulness and Critical Thinking.

PubMed

Noone, Chris; Bunting, Brendan; Hogan, Michael J

2015-01-01

Mindfulness originated in the Buddhist tradition as a way of cultivating clarity of thought. Despite the fact that this behavior is best captured using critical thinking (CT) assessments, no studies have examined the effects of mindfulness on CT or the mechanisms underlying any such possible relationship. Even so, mindfulness has been suggested as being beneficial for CT in higher education. CT is recognized as an important higher-order cognitive process which involves the ability to analyze and evaluate evidence and arguments. Such non-automatic, reflective responses generally require the engagement of executive functioning (EF) which includes updating, inhibition, and shifting of representations in working memory. Based on research showing that mindfulness enhances aspects of EF and certain higher-order cognitive processes, we hypothesized that individuals higher in facets of dispositional mindfulness would demonstrate greater CT performance, and that this relationship would be mediated by EF. Cross-sectional assessment of these constructs in a sample of 178 university students was achieved using the observing and non-reactivity sub-scales of the Five Factor Mindfulness Questionnaire, a battery of EF tasks and the Halpern Critical Thinking Assessment. Our hypotheses were tested by constructing a multiple meditation model which was analyzed using Structural Equation Modeling. Evidence was found for inhibition mediating the relationships between both observing and non-reactivity and CT in different ways. Indirect-only (or full) mediation was demonstrated for the relationship between observing, inhibition, and CT. Competitive mediation was demonstrated for the relationship between non-reactivity, inhibition, and CT. This suggests additional mediators of the relationship between non-reactivity and CT which are not accounted for in this model and have a negative effect on CT in addition to the positive effect mediated by inhibition. These findings are discussed in the context of the Default Interventionist Dual Process Theory of Higher-order Cognition and previous studies on mindfulness, self-regulation, EF, and higher-order cognition. In summary, dispositional mindfulness appears to facilitate CT performance and this effect is mediated by the inhibition component of EF. However, this relationship is not straightforward which suggests many possibilities for future research.

Does Mindfulness Enhance Critical Thinking? Evidence for the Mediating Effects of Executive Functioning in the Relationship between Mindfulness and Critical Thinking

PubMed Central

Noone, Chris; Bunting, Brendan; Hogan, Michael J.

2016-01-01

Mindfulness originated in the Buddhist tradition as a way of cultivating clarity of thought. Despite the fact that this behavior is best captured using critical thinking (CT) assessments, no studies have examined the effects of mindfulness on CT or the mechanisms underlying any such possible relationship. Even so, mindfulness has been suggested as being beneficial for CT in higher education. CT is recognized as an important higher-order cognitive process which involves the ability to analyze and evaluate evidence and arguments. Such non-automatic, reflective responses generally require the engagement of executive functioning (EF) which includes updating, inhibition, and shifting of representations in working memory. Based on research showing that mindfulness enhances aspects of EF and certain higher-order cognitive processes, we hypothesized that individuals higher in facets of dispositional mindfulness would demonstrate greater CT performance, and that this relationship would be mediated by EF. Cross-sectional assessment of these constructs in a sample of 178 university students was achieved using the observing and non-reactivity sub-scales of the Five Factor Mindfulness Questionnaire, a battery of EF tasks and the Halpern Critical Thinking Assessment. Our hypotheses were tested by constructing a multiple meditation model which was analyzed using Structural Equation Modeling. Evidence was found for inhibition mediating the relationships between both observing and non-reactivity and CT in different ways. Indirect-only (or full) mediation was demonstrated for the relationship between observing, inhibition, and CT. Competitive mediation was demonstrated for the relationship between non-reactivity, inhibition, and CT. This suggests additional mediators of the relationship between non-reactivity and CT which are not accounted for in this model and have a negative effect on CT in addition to the positive effect mediated by inhibition. These findings are discussed in the context of the Default Interventionist Dual Process Theory of Higher-order Cognition and previous studies on mindfulness, self-regulation, EF, and higher-order cognition. In summary, dispositional mindfulness appears to facilitate CT performance and this effect is mediated by the inhibition component of EF. However, this relationship is not straightforward which suggests many possibilities for future research. PMID:26834669

The Impact of Affective Constraints on Shaping Environmental Literacy: Model Testing Using Mediator and Moderator Variables

ERIC Educational Resources Information Center

Öztürk, Nilay; Teksöz, Gaye

2016-01-01

The aims of this study were; first to investigate the mediating effects of pre-service teachers' (PTs) attitude toward environment on the relationship between their environmental concern and environmental responsibility, and second, to explore the moderating effect of gender on the relationships between; PTs' environmental concern and…

Effects of Teacher Personalities on Emotional Exhaustion: Mediating Role of Emotional Labor

ERIC Educational Resources Information Center

Basim, H. Nejat; Begenirbas, Memduh; Can Yalcin, Rukiye

2013-01-01

One of the most indispensable and important elements of education is teachers whose personality closely affects training and education. In this context, this study examined the effects of teachers' personality traits on their emotional exhaustion in a mediating model which centers around emotional labor. Data were obtained from 798 teachers…

Effects of Teachers' Organizational Justice Perceptions on Intention to Quit: Mediation Role of Organizational Identification

ERIC Educational Resources Information Center

Basar, Ufuk; Sigri, Ünsal

2015-01-01

This research aims to discover the effects of teachers' organizational justice perceptions on intention to quit as well as the mediation role of teachers' organizational identification in this process. Interactions between research variables were measured using structural equation models. The sample used comprised teachers working at primary and…

Wuling powder prevents the depression-like behavior in learned helplessness mice model through improving the TSPO mediated-mitophagy.

PubMed

Li, Dongmei; Zheng, Ji; Wang, Mingyang; Feng, Lu; Liu, Yanyong; Yang, Nan; Zuo, Pingping

2016-06-20

Wuling powder (trade name: Wuling capsule), a traditional Chinese medicine (TCM), was extracted from mycelia of precious Xylaria Nigripes (Kl.) Sacc by modern fermentation technology, and has been claimed to be fully potent in improving the signs of insomnia and cognitive deficits. Moreover, Wuling capsule was effective in treating post-stroke and orther co-cormbid depression both in clinical and in basic research. In order to clarify the molecular mechanisms of the antidepressant effect of Wuling powder, we established learned helplessness (LH) depression animal model and focused on 18kDa translocator protein (TSPO) mediated-mitophagy pathway. Mice were exposed to the inescapable e-shock (IS) once a day for three consecutive days to establish the LH model. Then mice were orally administered Wuling powder for 2 weeks. For the behavioral assessment, Shuttle box test, novelty suppressed feeding test (NSF) and forced swimming test (FST) were performed. Following the behavioral assessment, we assessed the protein expression level that were related to TSPO-mediated mitophagy signaling pathway by Western blotting analysis. Finally, immunohistochemistry method was used to assess the neuroprotective effects of Wuling powder. Compared with mice that were subjected to inescapable e-shock, Wuling powder exhibited antidepressant effect in the multiple behavioral tests. In addition, Wuling powder altered the expression level of multiple proteins related to TSPO-mediated mitophagy signaling pathway. Our results suggested that Wuling powder exhibited an obvious antidepressant effect, which could be due to the improvement of TSPO-mediated mitophagy signaling pathway. Copyright © 2016. Published by Elsevier Ireland Ltd.

Psychological flexibility mediates change in intuitive eating regulation in acceptance and commitment therapy interventions.

PubMed

Sairanen, Essi; Tolvanen, Asko; Karhunen, Leila; Kolehmainen, Marjukka; Järvelä-Reijonen, Elina; Lindroos, Sanni; Peuhkuri, Katri; Korpela, Riitta; Ermes, Miikka; Mattila, Elina; Lappalainen, Raimo

2017-06-01

Despite the promising results related to intuitive eating, few studies have attempted to explain the processes encouraging this adaptive eating behaviour. The focus of the present study was on exploring mechanisms of change in intuitive eating and weight in acceptance and commitment therapy (ACT) interventions. Mediation provides important information regarding the treatment processes and theoretical models related to specific treatment approaches. The study investigates whether psychological flexibility, mindfulness skills and sense of coherence mediated the interventions' effect on intuitive eating and weight. Secondary analysis of a randomized control trial. Mediation analysis compared two ACT interventions - face-to-face (in a group) and mobile (individually) - with a control group using a latent difference score model. Settings Data were collected in three Finnish towns. The participants were overweight or obese (n 219), reporting symptoms of perceived stress. The effect of the interventions on participants' (i) BMI, (ii) intuitive eating and its subscales, (iii) eating for physical rather than emotional reasons and (iv) reliance on internal hunger and satiety cues was mediated by changes in weight-related psychological flexibility in both ACT groups. These findings suggest that ACT interventions aiming for lifestyle changes mediate the intervention effects through the enhanced ability to continue with valued activities even when confronted with negative emotions and thoughts related to weight.

Precompetitive achievement goals, stress appraisals, emotions, and coping among athletes.

PubMed

Nicholls, Adam R; Perry, John L; Calmeiro, Luis

2014-10-01

Grounded in Lazarus's (1991, 1999, 2000) cognitive-motivational-relational theory of emotions, we tested a model of achievement goals, stress appraisals, emotions, and coping. We predicted that precompetitive achievement goals would be associated with appraisals, appraisals with emotions, and emotions with coping in our model. The mediating effects of emotions among the overall sample of 827 athletes and two stratified random subsamples were also explored. The results of this study support our proposed model in the overall sample and the stratified subsamples. Further, emotion mediated the relationship between appraisal and coping. Mediation analyses revealed that there were indirect effects of pleasant and unpleasant emotions, which indicates the importance of examining multiple emotions to reveal a more accurate representation of the overall stress process. Our findings indicate that both appraisals and emotions are just as important in shaping coping.

Peer Support and Adolescents' Physical Activity: The Mediating Roles of Self-Efficacy and Enjoyment.

PubMed

Chen, Han; Sun, Haichun; Dai, Jun

2017-06-01

The present study aimed to contrast the mediating magnitude of self-efficacy and enjoyment connecting peer support and adolescents' physical activity (PA). Participants were 9th-12th grade students ( N  = 409; 56.5% boys) who were randomly chosen from six public schools located in Fuzhou city in southeast China. The bootstrapping method in structural equation modeling was conducted to examine the direct and indirect effects of peer support on adolescents' PA. Peer support did not directly impact PA. Rather, peer support indirectly influenced PA through either self-efficacy or enjoyment, with self-efficacy demonstrating a stronger mediating effect. Additionally, we found a significant serial mediating effect with enjoyment, and self-efficacy sequentially mediated the relationship between peer support and PA. The findings highlight the role of self-efficacy and enjoyment as mediators connecting peer support and PA. Self-efficacy seems to be more important, as it demonstrated a significantly greater mediating effect. © The Author 2017. Published by Oxford University Press on behalf of the Society of Pediatric Psychology. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com

Emotional states as mediators between tinnitus loudness and tinnitus distress in daily life: Results from the “TrackYourTinnitus” application

PubMed Central

Probst, Thomas; Pryss, Rüdiger; Langguth, Berthold; Schlee, Winfried

2016-01-01

The psychological process how tinnitus loudness leads to tinnitus distress remains unclear. This cross-sectional study investigated the mediating role of the emotional state “stress level” and of the two components of the emotional state “arousal” and “valence” with N = 658 users of the “TrackYourTinnitus” smartphone application. Stress mediated the relationship between tinnitus loudness and tinnitus distress in a simple mediation model and even in a multiple mediation model when arousal and valence were held constant. Arousal mediated the loudness-distress relationship when holding valence constant, but not anymore when controlling for valence as well as for stress. Valence functioned as a mediator when controlling for arousal and even when holding arousal and stress constant. The direct effect of tinnitus loudness on tinnitus distress remained significant in all models. This study demonstrates that emotional states affect the process how tinnitus loudness leads to tinnitus distress. We thereby could show that the mediating influence of emotional valence is at least equally strong as the influence of stress. Implications of the findings for future research, assessment, and clinical management of tinnitus are discussed. PMID:26853815

The role of ingroup threat and conservative ideologies on prejudice against immigrants in two samples of Italian adults.

PubMed

Caricati, Luca; Mancini, Tiziana; Marletta, Giuseppe

2017-01-01

This research investigated the relationship among perception of ingroup threats (realistic and symbolic), conservative ideologies (social dominance orientation [SDO] and right-wing authoritarianism [RWA]), and prejudice against immigrants. Data were collected with a cross-sectional design in two samples: non-student Italian adults (n = 223) and healthcare professionals (n = 679). Results were similar in both samples and indicated that symbolic and realistic threats, as well as SDO and RWA, positively and significantly predicted anti-immigrant prejudice. Moreover, the model considering SDO and RWA as mediators of threats' effects on prejudice showed a better fit than the model in which ingroup threats mediated the effects of SDO and RWA on prejudice against immigrants. Accordingly, SDO and RWA partially mediated the effect of both symbolic and realistic threats, which maintained a significant effect on prejudice against immigrants, however.

The efficacy of teachers' responses to incidents of bullying and victimization: The mediational role of moral disengagement for bullying.

PubMed

Campaert, Kristel; Nocentini, Annalaura; Menesini, Ersilia

2017-09-01

Teachers respond differently to bullying and victimization. Socio-cognitive and moral domain theory suggest that students process teachers' behavior cognitively and that teachers' responses to incidents of bullying and victimization could affect students' level of moral disengagement. We examined the mediating effect of students' moral disengagement between types of teachers' responses to situations of bullying and victimization and individual bullying using multilevel mediation modelling. Participants were 609 students (50% boys, age M = 11.47, SD = 1.14) of central Italy, nested in 34 classes. Students rated the frequency of self-reported bullying and of teachers' responses to incidents of bullying and victimization on a 5-point Likert scale. Teachers' responses to bullying included non-intervention, mediation, group discussion, and sanctions. Teachers' responses to victimization included non-intervention, mediation, group discussion, and victim support. Results indicated that in the teachers' responses to incidents of bullying model, a significant indirect effect of non-intervention (β = .03; 95%CI [.01, .05]) and of sanctions (β = -.02; 95%CI [-.04, -.01]) on bullying through moral disengagement was found at the individual level. Similarly, in the model on teachers' responses toward victims there was a significant indirect effect through moral disengagement of non-intervention (β = .03; 95%CI [.02, .04]) and victim support (β = -.01; 95%CI [-.02, -.001]). At the class level there were no significant indirect effects. In sum, results indicated that moral disengagement is an important mediator at the individual level and suggest including teachers in anti-bullying interventions with a specific focus on their role for moral development. © 2017 Wiley Periodicals, Inc.

Parenting intervention effects on parental depressive symptoms: examining the role of parenting and child behavior.

PubMed

Wong, Jessie J; Gonzales, Nancy A; Montaño, Zorash; Dumka, Larry; Millsap, Roger E

2014-06-01

Parental depression is a major risk factor in child development. Growing research suggests parenting programs can positively impact parental depressive symptoms, although the specific mechanisms that explain these effects are unknown. The current study examined parenting mediated effects of a parenting program on mothers' and fathers' depressive symptoms, as well as the role of child behavior in linking parenting to reductions in depressive symptoms. The study samples included 494 mothers and 288 fathers of Mexican origin adolescents who participated in a randomized trial of the Bridges to High School Program/Proyecto Puentes a la Secundaria, a universal prevention and promotion intervention that included parent training but did not directly target parental depressive symptoms. Parenting mediator models tested program effects on parental depressive symptoms through changes in harsh and supportive parenting. Results showed a significant indirect intervention effect on maternal depressive symptoms through changes in mothers' harsh parenting. Next, child behavior models revealed a partial mediation effect of harsh parenting and a full mediation effect of supportive parenting on maternal depressive symptoms through mothers' reports of child externalizing symptoms. Indirect effects of fathers' harsh and supportive parenting on paternal depressive symptoms were also found through fathers' reports of child behavior. PsycINFO Database Record (c) 2014 APA, all rights reserved.

A multiple mediator analysis approach to quantify the effects of the ADH1B and ALDH2 genes on hepatocellular carcinoma risk.

PubMed

Shih, Stephannie; Huang, Yen-Tsung; Yang, Hwai-I

2018-06-01

Previous work suggested a genetic component affecting the risk of hepatocellular carcinoma (HCC) and mediation analyses have elucidated potential indirect pathways of these genetic effects. Specifically, the effects of alcohol dehydrogenase (ADH1B) and aldehyde dehydrogenase (ALDH2) genes on HCC risk vary based on alcohol consumption habits. However, alcohol consumption may not be the only mediator in the identified pathway: factors related to alcohol consumption may contribute to the same indirect pathway. Thus, we developed a multimediator model to quantify the genetic effects on HCC risk through sequential dichotomous mediators under the counterfactual framework. Our method provided a closed form formula for the mediation effects through different indirect paths, which requires no assumption for the rarity of outcome. In simulation studies of a finite sample, we presented the utility of the method with the variance of the effects estimated using the delta method and bootstrapping. We applied our method to data from participants in Taiwan (580 cases and 3,207 controls) and quantified the mediation effects of single nucleotide polymorphisms (SNPs) in the ADH1B and ALDH2 genes on HCC through alcohol consumption (yes/no) and high alanine transaminase (ALT) levels (greater than or equal to 45 U/L or below 45 U/L). Assuming a dominant risk model, we identified that the SNPs' effects through alcohol consumption is more significant than through ALT levels on HCC risk. This new method provides insight to the magnitude of various casual mechanisms as a closed form solution and can be readily applied in other genomic studies. © 2018 WILEY PERIODICALS, INC.

Adolescent impulsivity and soft drink consumption: The role of parental regulation.

PubMed

Melbye, Elisabeth L; Bergh, Ingunn H; Hausken, Solveig E S; Sleddens, Ester F C; Glavin, Kari; Lien, Nanna; Bjelland, Mona

2016-01-01

The present study aimed to explore the process in which impulsivity might influence soft drink consumption in adolescents, addressing potential mediating effects of perceived parental regulation regarding unhealthy eating. A cross-sectional survey was performed among 440 13-15-year-olds in Eastern Norway. The survey questionnaire included measures of impulsivity, six types of maternal and paternal regulation (as perceived by the adolescents), and consumption of sugar-sweetened beverages (SSB). Parallel multiple-mediator analyses were performed to reveal potential mediating effects of perceived parental regulatory behaviors on the association between adolescent impulsivity and SSB consumption. Separate models were run for maternal and paternal regulation. Results from our model analyses (both maternal and paternal models) indicated that all the six measured parental regulatory behaviors jointly acted as mediators on the association between adolescent impulsivity and SSB consumption. However, only perceived maternal and paternal legitimacy of regulation showed a unique contribution to the mediated effect. This finding suggests that adolescents' perception of parental legitimate authority is of particular importance in explaining the relationship between impulsivity and unhealthy eating behaviors in adolescents. Future nutrition interventions targeting adolescents and their parents should take personal factors such as adolescents' level of impulsivity into account. Ultimately; what may be an appropriate approach to impulsive individuals and their parents may diverge from what may be an appropriate approach to less impulsive individuals and their parents. Copyright © 2015 Elsevier Ltd. All rights reserved.

Contingency management for college student smokers: The role of drinking as a moderator and mediator of smoking abstinence during treatment.

PubMed

Cassidy, Rachel N; Jackson, Kristina M; Rohsenow, Damaris J; Tidey, Jennifer W; Tevyaw, Tracy O' L; Barnett, Nancy P; Monti, Peter M; Miller, Mollie E; Colby, Suzanne M

2018-05-01

Contingency management (CM) is effective for promoting smoking abstinence; however, moderators and mediators of CM treatment efficacy in young adult populations are under-explored. We leveraged fine-grained data from a large randomized controlled trial: 1) to determine whether early attainment of sustained abstinence mediated the effect of treatment on abstinence; 2) to test whether heavy drinking moderated the effect of treatment on abstinence; and 3) to test a serial mediation model of the effects of drinking during early treatment on sustained smoking abstinence. College student smokers (N=110) were randomized to receive either CM treatment or noncontingent reinforcement (NR) over a 21-day treatment period. All participants received $5 for providing twice-daily breath carbon monoxide (CO) samples. In CM, additional money was provided for samples that indicated smoking reduction (Initial Phase; first 7days), and for samples ≤5ppm (Abstinence Phase; following 14days). CM treatment led to greater sustained abstinence relative to NR. Longer sustained abstinence in the Initial Phase partially mediated the effect of treatment on sustained abstinence in the Abstinence Phase. Heavier pretreatment drinkers had shorter periods of sustained abstinence in the Abstinence Phase; this effect was greater in CM. A serial mediation model determined that increased drinking during the Initial Phase led to decreased sustained abstinence, which then led to decreased sustained abstinence in the Abstinence Phase. These data provide a greater understanding of how heavy drinking and early sustained abstinence may affect success during treatment in young adults undergoing contingency management treatment for smoking. Copyright © 2018. Published by Elsevier Ltd.

Positive smoking outcome expectancies mediate the association between negative affect and smoking urge among women during a quit attempt.

PubMed

Cano, Miguel Ángel; Lam, Cho Y; Chen, Minxing; Adams, Claire E; Correa-Fernández, Virmarie; Stewart, Diana W; McClure, Jennifer B; Cinciripini, Paul M; Wetter, David W

2014-08-01

Ecological momentary assessment was used to examine associations between negative affect, positive smoking outcome expectancies, and smoking urge during the first 7 days of a smoking quit attempt. Participants were 302 female smokers who enrolled in an individually tailored smoking cessation treatment study. Multilevel mediation analysis was used to examine the temporal relationship among the following: (a) the effects of negative affect and positive smoking outcome expectancies at 1 assessment point (e.g., time j) on smoking urge at the subsequent time point (e.g., time j + 1) in Model 1; and, (b) the effects of negative affect and smoking urge at time j on positive smoking outcome expectancies at time j + 1 in Model 2. The results from Model 1 showed a statistically significant effect of negative affect at time j on smoking urge at time j + 1, and this effect was mediated by positive smoking outcome expectancies at time j, both within- and between-participants. In Model 2, the within-participant indirect effect of negative affect at time j on positive smoking outcome expectancies at time j + 1 through smoking urge at time j was nonsignificant. However, a statistically significant indirect between-participants effect was found in Model 2. The findings support the hypothesis that urge and positive smoking outcome expectancies increase as a function of negative affect, and suggest a stronger effect of expectancies on urge as opposed to the effect of urge on expectancies.

Positive Smoking Outcome Expectancies Mediate the Association between Negative Affect and Smoking Urge among Women During a Quit Attempt

PubMed Central

Cano, Miguel Ángel; Lam, Cho Y.; Chen, Minxing; Adams, Claire E.; Correa-Fernández, Virmarie; Stewart, Diana W.; McClure, Jennifer B.; Cinciripini, Paul M.; Wetter, David W.

2014-01-01

Ecological momentary assessment was used to examine associations between negative affect, positive smoking outcome expectancies, and smoking urge during the first 7 days of a smoking quit attempt. Participants were 302 female smokers who enrolled in an individually tailored smoking cessation treatment study. Multilevel mediation analysis was used to examine the temporal relationship among: 1) the effects of negative affect and positive smoking outcome expectancies at one assessment point (e.g., time j) on smoking urge at the subsequent time point (e.g., time j + 1) in Model 1; and, 2) the effects of negative affect and smoking urge at time j on positive smoking outcome expectancies at time j + 1 in Model 2. The results from Model 1 showed a statistically significant effect of negative affect at time j on smoking urge at time j + 1, and this effect was mediated by positive smoking outcome expectancies at time j, both within- and between-participant. In Model 2, the within-participant indirect effect of negative affect at time j on positive smoking outcome expectancies at time j + 1 through smoking urge at time j was nonsignificant. However, a statistically significant indirect between-participant effect was found in Model 2. The findings support the hypothesis that urge and positive smoking outcome expectancies increase as a function of negative affect, and suggest a stronger effect of expectancies on urge as opposed to the effect of urge on expectancies. PMID:24796849

Negative affect mediates the relationship between interpersonal problems and binge-eating disorder symptoms and psychopathology in a clinical sample: a test of the interpersonal model.

PubMed

Ivanova, Iryna V; Tasca, Giorgio A; Hammond, Nicole; Balfour, Louise; Ritchie, Kerri; Koszycki, Diana; Bissada, Hany

2015-03-01

This study evaluated the validity of the interpersonal model of binge-eating disorder (BED) psychopathology in a clinical sample of women with BED. Data from a cross-sectional sample of 255 women with BED were examined for the direct effects of interpersonal problems on BED symptoms and psychopathology, and indirect effects mediated by negative affect. Structural equation modelling analyses demonstrated that higher levels of interpersonal problems were associated with greater negative affect, and greater negative affect was associated with higher frequency of BED symptoms and psychopathology. There was a significant indirect effect of interpersonal problems on BED symptoms and psychopathology mediated through negative affect. Interpersonal problems may lead to greater BED symptoms and psychopathology, and this relationship may be partially explained by elevated negative affect. The results of the study are the first to provide support for the interpersonal model of BED symptoms and psychopathology in a clinical sample of women. Copyright © 2015 John Wiley & Sons, Ltd and Eating Disorders Association.

Discrimination, Subjective Wellbeing, and the Role of Gender: A Mediation Model of LGB Minority Stress.

PubMed

Conlin, Sarah E; Douglass, Richard P; Ouch, Staci

2017-10-26

The present study examined the link between discrimination and the three components of subjective wellbeing (positive and negative affect and life satisfaction) among a cisgender sample of lesbian, gay, and bisexual (LGB) adults. Specifically, we investigated internalized homonegativity and expectations of rejection as potential mediators of the links between discrimination and subjective wellbeing among a sample of 215 participants. Results from our structural equation model demonstrated a strong, positive direct link between discrimination and negative affect. Discrimination also had small, negative indirect effects on life satisfaction through our two mediators. Interestingly, neither discrimination nor our two mediators were related with positive affect, demonstrating the need for future research to uncover potential buffers of this link. Finally, our model evidenced configural, metric, and scalar invariance, suggesting that our model applies well for both women and men. Practical implications and future directions for research are discussed.

The Contributing Risk of Tobacco Use for ARDS Development in Burn-Injured Adults With Inhalation Injury.

PubMed

Afshar, Majid; Netzer, Giora; Mosier, Michael J; Cooper, Richard S; Adams, William; Burnham, Ellen L; Kovacs, Elizabeth J; Durazo-Arvizu, Ramon; Kliethermes, Stephanie

2017-11-01

This study aims to determine the relationship between tobacco use, inhalation injury, and ARDS in burn-injured adults. This study was an observational cohort of 2,485 primary burn admissions to a referral burn center between January 1, 2008 and March 15, 2015. Subjects were evaluated by methods used to account for mediation and traditional approaches (multivariable logistic regression and propensity score analysis). Mediation analysis examined both the (1) indirect effect of tobacco use via inhalation injury as the mediator on ARDS development and (2) the direct effect of tobacco use alone on ARDS development. ARDS development occurred in 6.8% ( n = 170) of the cohort. Inhalation injury occurred in 5.0% ( n = 125) of the cohort, and ARDS developed in 48.8% ( n = 83) of the subjects with inhalation injury. Tobacco use was 2-fold more common in subjects with ARDS. In the mediated model, the direct effect of tobacco use on ARDS, including interaction between tobacco use and inhalation injury, was not significant (odds ratio [OR] 1.63, 95% CI 0.91-2.92, P = .10). However, the indirect effect of tobacco use via inhalation injury as the mediator was significant (OR 1.61, 95% CI 1.25-2.07, P < .001), and the proportion of the total effect of tobacco use operating through the mediator was 55.6%. In the non-mediation models (multivariable logistic regression and propensity score analysis), which controlled for inhalation injury and other covariables, the OR for the association between tobacco use and ARDS was 1.84 (95% CI 1.22-2.81, P < .001) and 1.69 (95% CI 1.04-2.75, P = .03), respectively. In mediation analysis, inhalation injury was the overwhelming predictor for ARDS development, whereas tobacco use has its strongest effect indirectly through inhalation injury. Patients with at least moderate inhalation injury are at greatest risk for ARDS development despite baseline risk factors like tobacco use. Copyright © 2017 by Daedalus Enterprises.

Behavioral and Nondirective Guided Self-Help for Parents of Children with Externalizing Behavior: Mediating Mechanisms in a Head-To-Head Comparison.

PubMed

Katzmann, Josepha; Hautmann, Christopher; Greimel, Lisa; Imort, Stephanie; Pinior, Julia; Scholz, Kristin; Döpfner, Manfred

2017-05-01

Parent training (PT) delivered as a guided self-help intervention may be a cost- and time-effective intervention in the treatment of children with externalizing disorders. In face-to-face PT, parenting strategies have repeatedly been identified as mediating mechanisms for the decrease of children's problem behavior. Few studies have examined possible mediating effects in guided self-help interventions for parents. The present study aimed to investigate possible mediating variables of a behaviorally oriented guided self-help program for parents of children with externalizing problems compared to a nondirective intervention in a clinical sample. A sample of 110 parents of children with externalizing disorders (80 % boys) were randomized to either a behaviorally oriented or a nondirective guided self-help program. Four putative mediating variables were examined simultaneously in a multiple mediation model using structural equation modelling. The outcomes were child symptoms of ADHD and ODD as well as child externalizing problems, assessed at posttreatment. Analyses showed a significant indirect effect for dysfunctional parental attributions in favor of the group receiving the behavioral program, and significant effects of the behavioral program on positive and negative parenting and parental self-efficacy, compared to the nondirective intervention. Our results indicate that a decrease of dysfunctional parental attributions leads to a decrease of child externalizing problems when parents take part in a behaviorally oriented guided self-help program. However, none of the putative mediating variables could explain the decrease in child externalizing behavior problems in the nondirective group. A change in dysfunctional parental attributions should be considered as a possible mediator in the context of PT.

Mediating effects of depression and anxiety on the relationship between bullying involvement and pain problems among adolescents in Taiwan.

PubMed

Yen, Cheng-Fang; Lin, I-Mei; Liu, Tai-Ling; Hu, Huei-Fan; Cheng, Chung-Ping

2014-08-01

This study aimed to examine the mediating effects of depression and anxiety on the relationships of bullying victimization and perpetration with pain among adolescents in Taiwan. A total of 4976 students of junior and senior high schools completed the questionnaires. Bullying victimization and perpetration, pain problems, depression, and anxiety were assessed. The mediating effects of depression and anxiety on the relationship between bullying involvement and pain problems and the moderating effects of sex on the medicating roles of depression and anxiety were examined by structural equation model. Both depression and anxiety were significant mediators of the relationship between bullying victimization and pain problems among adolescents. Depression was also a significant mediator of the relationship between bullying perpetration and pain problems among adolescents. Sex had no moderating effect on the mediating role of depression/anxiety on the association between bullying involvement and pain problems. Medical and educational professionals should survey and intervene in depression and anxiety when managing pain problems among adolescents involved in bullying. Copyright © 2014 Elsevier Inc. All rights reserved.

Examining a Sequential Mediation Model of Chinese University Students’ Well-Being: A Career Construction Perspective

PubMed Central

Zhuang, Mingke; She, Zhuolin; Cai, Zijun; Huang, Zheng; Xiang, Qian; Wang, Ping; Zhu, Fei

2018-01-01

Despite career construction theory attends to individual subjective career and provides a useful lens to study well-being, extant research has yielded limited insights into the mechanisms through which career construction variables influence individual well-being. To address this important gap, the present study examined a mediation model that links indicators of career adaptivity (big-five personality and approach/avoidance traits) to psychological well-being (psychological flourishing and life satisfaction) through career adaptability and in sequent meaning of life (presence of life meaning and search for life meaning) among a sample of Chinese university students (N = 165). The results of a two-wave survey study showed that career adaptability and presence of life meaning mediated the effects of openness to experience, consciousness, approach trait, and avoidance trait on individual well-being in sequence. The results also showed that approach trait’s effect on presence of meaning was partially mediated by career adaptability; career adaptability’s effect on psychological flourishing was partially mediated by presence of meaning. These findings advance understanding of antecedents to individual well-being from a career construction perspective, and carry implications for career education and counseling practices. PMID:29743876

Regulatory focus and burnout in nurses: The mediating effect of perception of transformational leadership.

PubMed

Shi, Rui; Zhang, Shilei; Xu, Hang; Liu, Xufeng; Miao, Danmin

2015-12-01

This correlation study investigated the relationship between nurses' regulatory focus and burnout, as mediated by their perceptions of transformational leadership, using a cross-sectional research design with anonymous questionnaires. In July-August 2012, data were collected from 378 nurses from three hospitals in Shaanxi Province, China, using self-report questionnaires for measuring the nurses' regulatory focus, their level of burnout and their perception of whether the leadership of their supervisor was transformational. Structural equation modelling and bootstrapping procedures were used to identify the mediating effect of their perceptions of transformational leadership. The results supported our hypothesized model. The type of regulatory focus emerged as a significant predictor of burnout. Having a perception of transformational leadership partially mediated the relationship between regulatory focus and burnout. Having a promotion focus reduced burnout when the participants perceived transformational leadership, whereas having a prevention focus exhibited the opposite pattern. The mediating effect of the perception of transformational leadership suggests that a promotion focus may help diminish burnout, directly and indirectly. Nurse managers must be aware of the role of a regulatory focus and cultivate promotion focus in their followers. © 2014 Wiley Publishing Asia Pty Ltd.

Examining a Sequential Mediation Model of Chinese University Students' Well-Being: A Career Construction Perspective.

PubMed

Zhuang, Mingke; She, Zhuolin; Cai, Zijun; Huang, Zheng; Xiang, Qian; Wang, Ping; Zhu, Fei

2018-01-01

Despite career construction theory attends to individual subjective career and provides a useful lens to study well-being, extant research has yielded limited insights into the mechanisms through which career construction variables influence individual well-being. To address this important gap, the present study examined a mediation model that links indicators of career adaptivity (big-five personality and approach/avoidance traits) to psychological well-being (psychological flourishing and life satisfaction) through career adaptability and in sequent meaning of life (presence of life meaning and search for life meaning) among a sample of Chinese university students ( N = 165). The results of a two-wave survey study showed that career adaptability and presence of life meaning mediated the effects of openness to experience, consciousness, approach trait, and avoidance trait on individual well-being in sequence. The results also showed that approach trait's effect on presence of meaning was partially mediated by career adaptability; career adaptability's effect on psychological flourishing was partially mediated by presence of meaning. These findings advance understanding of antecedents to individual well-being from a career construction perspective, and carry implications for career education and counseling practices.

Differential Fc-receptor engagement drives an anti-tumor vaccinal effect

PubMed Central

DiLillo, David J.; Ravetch, Jeffrey V.

2015-01-01

Summary Passively-administered anti-tumor mAbs rapidly kill tumor targets via FcγR-mediated cytotoxicity (ADCC), a short-term process. However, anti-tumor mAb treatment can also induce a vaccinal effect, in which mAb-mediated tumor death induces a long-term anti-tumor cellular immune response. To determine how such responses are generated, we utilized a murine model of an anti-tumor vaccinal effect against a model neoantigen. We demonstrate that FcγR expression by CD11c+ antigen-presenting cells is required to generate anti-tumor T cell responses upon ADCC-mediated tumor clearance. Using FcγR-humanized mice, we demonstrate that anti-tumor huIgG1 must engage hFcγRIIIA on macrophages to mediate ADCC, but also engage hFcγRIIA, the sole hFcγR expressed by human DCs, to generate a potent vaccinal effect. Thus, while next-generation anti-tumor antibodies with enhanced binding to only hFcγRIIIA are now in clinical use, ideal anti-tumor antibodies must be optimized for both cytotoxic effects as well as hFcγRIIA engagement on DCs to stimulate long-term anti-tumor cellular immunity. PMID:25976835

Effects of early maternal distress and parenting on the development of children's self-regulation and externalizing behavior.

PubMed

Choe, Daniel Ewon; Olson, Sheryl L; Sameroff, Arnold J

2013-05-01

Emotional distress experienced by mothers increases young children's risk of externalizing problems through suboptimal parenting and child self-regulation. An integrative structural equation model tested hypotheses that mothers' parenting (i.e., low levels of inductive discipline and maternal warmth) would mediate adverse effects of early maternal distress on child effortful control, which in turn would mediate effects of maternal parenting on child externalizing behavior. This longitudinal study spanning ages 3, 6, and 10 included 241 children, mothers, and a subset of teachers. The hypothesized model was partially supported. Elevated maternal distress was associated with less inductive discipline and maternal warmth, which in turn were associated with less effortful control at age 3 but not at age 6. Inductive discipline and maternal warmth mediated adverse effects of maternal distress on children's effortful control. Less effortful control at ages 3 and 6 predicted smaller relative decreases in externalizing behavior at 6 and 10, respectively. Effortful control mediated effects of inductive discipline, but not maternal warmth, on externalizing behavior. Findings suggest elevated maternal distress increases children's risk of externalizing problems by compromising early parenting and child self-regulation.

Contingency learning is reduced for high conflict stimuli.

PubMed

Whitehead, Peter S; Brewer, Gene A; Patwary, Nowed; Blais, Chris

2016-09-16

Recent theories have proposed that contingency learning occurs independent of control processes. These parallel processing accounts propose that behavioral effects originally thought to be products of control processes are in fact products solely of contingency learning. This view runs contrary to conflict-mediated Hebbian-learning models that posit control and contingency learning are parts of an interactive system. In this study we replicate the contingency learning effect and modify it to further test the veracity of the parallel processing accounts in comparison to conflict-mediated Hebbian-learning models. This is accomplished by manipulating conflict to test for an interaction, or lack thereof, between conflict and contingency learning. The results are consistent with conflict-mediated Hebbian-learning in that the addition of conflict reduces the magnitude of the contingency learning effect. Copyright © 2016 Elsevier B.V. All rights reserved.

Evaluation of Target Specificity of Antibacterial Agents Using Staphylococcus aureus ddlA Mutants and d-Cycloserine in a Silkworm Infection Model▿

PubMed Central

Kurokawa, Kenji; Hamamoto, Hiroshi; Matsuo, Miki; Nishida, Satoshi; Yamane, Noriko; Lee, Bok Luel; Murakami, Kazuhisa; Maki, Hideki; Sekimizu, Kazuhisa

2009-01-01

The availability of a silkworm larva infection model to evaluate the therapeutic effectiveness of antibiotics was examined. The 50% effective doses (ED50) of d-cycloserine against the Staphylococcus aureus ddlA mutant-mediated killing of larvae were remarkably lower than those against the parental strain-mediated killing of larvae. Changes in MICs and ED50 of other antibiotics were negligible, suggesting that these alterations are d-cycloserine selective. Therefore, this model is useful for selecting desired compounds based on their therapeutic effectiveness during antibiotic development. PMID:19546371

Relationship between work-family balance and job satisfaction among employees in China: A moderated mediation model.

PubMed

Yu, Yue; Wang, Yuchen; Zhang, Jianxin

2017-09-01

Previous studies have revealed the association between work-family balance and job satisfaction. The present research further explored the underlying mechanism of this association and aimed to provide a moderated mediation model to explain if personality traits moderate the relationship between work-family balance and job satisfaction through work engagement. A cross-sectional study was conducted in which 263 employees from a petrochemical enterprise in China completed self-report questionnaires including the Work-Family Balance Scale, the Utrecht Work Engagement Scale, the Big Five Inventory-10, and the Job Satisfaction Scale. Hierarchical regression analysis and structural equation modeling showed that work engagement partially mediated the relationship between work-family balance and job satisfaction, and the indirect effect was further moderated only by extraversion. Therefore, an integrative moderated mediation model was proposed wherein work-family balance boosts job satisfaction by first enhancing employees' work engagement, while the indirect effect was in turn moderated by extraversion. The results suggest that interventions for improving job satisfaction may be enhanced by targeting work engagement, especially for employees with higher extraversion. © 2017 The Institute of Psychology, Chinese Academy of Sciences and John Wiley & Sons Australia, Ltd.

Effort-reward imbalance and organisational injustice among aged nurses: a moderated mediation model.

PubMed

Topa, Gabriela; Guglielmi, Dina; Depolo, Marco

2016-09-01

To test the effort-reward imbalance model among older nurses, expanding it to include the moderation of overcommitment and age in the stress-health complaints relationship, mediated by organisational injustice. The theoretical framework included the effort-reward imbalance, the uncertainty management and the socio-emotional selectivity models. Employing a two-wave design, the participants were 255 nurses aged 45 years and over, recruited from four large hospitals in Spain (Madrid and Basque Country). The direct effect of imbalance on health complaints was supported: it was significant when overcommitment was low but not when it was high. Organisational injustice mediated the influence of effort-reward imbalance on health complaints. The conditional effect of the mediation of organisational injustice was significant in three of the overcommitment/age conditions but it weakened, becoming non-significant, when the level of overcommitment was low and age was high. The study tested the model in nursing populations and expanded it to the settings of occupational health and safety at work. The results of this study highlight the importance of effort-reward imbalance and organisational justice for creating healthy work environments. © 2016 John Wiley & Sons Ltd.

Mother-child relationship quality and effective discipline as mediators of the 6-year effects of the New Beginnings Program for children from divorced families.

PubMed

Zhou, Qing; Sandler, Irwin N; Millsap, Roger E; Wolchik, Sharlene A; Dawson-McClure, Spring R

2008-08-01

This study examines whether program effects on mother-child relationship quality and effective discipline mediated the 6-year longitudinal effects of the New Beginnings Program (NBP) to improve mental health and competence outcomes in 218 adolescents from divorced families in a randomized experimental trial. The NBP is a theory-based and parenting-focused preventive intervention to help children adjust to divorce, and it has previously shown significant main and/or Program x Baseline Risk interaction effects to reduce adolescents' mental health and social adaptation problems and to promote competence. Mediation analyses were conducted using single- and two-group (high and low baseline risk) structural equation modeling. A multiple-methods and multiple-informants approach was used to assess the putative mediators and adolescents' outcomes. Results indicated that program-induced improvement in maternal effective discipline at posttest mediated the intervention effect on adolescents' GPA at the 6-year follow-up. Moreover, program-induced improvement in mother-child relationship quality mediated the intervention effect on adolescents' mental health problems for those with high baseline risk for maladjustment. The discussion focuses on the implications of the mediation findings for advancing the developmental theories that informed the design of the NBP and the implications for implementation of the NBP in community settings. Copyright 2008 APA, all rights reserved.

The Relationship Among School Safety, School Liking, and Students' Self-Esteem: Based on a Multilevel Mediation Model.

PubMed

Zhang, Xinghui; Xuan, Xin; Chen, Fumei; Zhang, Cai; Luo, Yuhan; Wang, Yun

2016-03-01

Perceptions of school safety have an important effect on students' development. Based on the model of "context-process-outcomes," we examined school safety as a context variable to explore how school safety at the school level affected students' self-esteem. We used hierarchical linear modeling to examine the link between school safety at the school level and students' self-esteem, including school liking as a mediator. The data were from the National Children's Study of China (NCSC), in which 6618 fourth- to fifth-grade students in 79 schools were recruited from 100 counties in 31 provinces in China. Multilevel mediation analyses showed that the positive relationship between school safety at the school level and self-esteem was partially mediated by school liking, controlling for demographics at both student and school levels. Furthermore, a sex difference existed in the multilevel mediation model. For boys, school liking fully mediated the relationship between school safety at the school level and self-esteem. However, school liking partially mediated the relationship between school safety at the school level and self-esteem among girls. School safety should receive increasing attention from policymakers because of its impact on students' self-esteem. © 2016, American School Health Association.

The role of social media use in improving cancer survivors' emotional well-being: a moderated mediation study.

PubMed

Jiang, Shaohai

2017-06-01

In the USA, levels of emotional well-being among cancer survivors remain low. Social media is recognized as important to improve their emotional well-being. However, little is known about social mechanisms that underlie the impact of health-related social media in cancer care. This study proposed a moderated mediation model to signify a pathway linking social media use to emotional well-being. Four-hundred and fifty-nine cancer survivors identified through the 2013 US-based Health Information National Trends Survey were included for data analysis. First, structural equation modeling was conducted to examine the path from social media use to emotional well-being, mediated by patient activation. Second, hierarchical regression was performed to test the moderation effect of emotion management. Last, a normal theory-based approach was used to explore the final moderated mediation model. The effect of health-related social media use on emotional well-being was completely mediated by patient activation. Also, emotion management positively moderated the effect of patient activation on emotional well-being. Last, emotion management positively moderated the mediation pathway from health-related social media use to patient activation, and finally, to emotional well-being. Health-related social media, by itself, is not sufficient to bring about improvement in cancer survivors' emotional well-being. Patient activation and emotion management play a significant role. In future interventions designed to improve cancer survivors' emotional health, health practitioners should not only encourage cancer survivors to use social media for health purposes, but also activate them in the course of care, and improve their emotion self-management skills.

Indirect Effects of Environmental Change in Resource Competition Models.

PubMed

Kleinhesselink, Andrew R; Adler, Peter B

2015-12-01

Anthropogenic environmental change can affect species directly by altering physiological rates or indirectly by changing competitive outcomes. The unknown strength of competition-mediated indirect effects makes it difficult to predict species abundances in the face of ongoing environmental change. Theory developed with phenomenological competition models shows that indirect effects are weak when coexistence is strongly stabilized, but these models lack a mechanistic link between environmental change and species performance. To extend existing theory, we examined the relationship between coexistence and indirect effects in mechanistic resource competition models. We defined environmental change as a change in resource supply points and quantified the resulting competition-mediated indirect effects on species abundances. We found that the magnitude of indirect effects increases in proportion to niche overlap. However, indirect effects also depend on differences in how competitors respond to the change in resource supply, an insight hidden in nonmechanistic models. Our analysis demonstrates the value of using niche overlap to predict the strength of indirect effects and clarifies the types of indirect effects that global change can have on competing species.

Anti-inflammatory effects of traditional mixed extract of medicinal herbs (MEMH) on monosodium urate crystal-induced gouty arthritis.

PubMed

Nam, Ju-Suk; Jagga, Supriya; Sharma, Ashish Ranjan; Lee, Joon-Hee; Park, Jong Bong; Jung, Jun-Sub; Lee, Sang-Soo

2017-08-01

Korean oriental medicine prescription is widely used for the treatment of gouty diseases. In the present study, we investigated anti-inflammatory effects of modified Korean herbal formulation, mixed extract of medicinal herbs (MEMH), and its modulatory effects on inflammatory mediators associated with gouty arthritis. Both in vitro and in vivo studies were carried out to assess the anti-inflammatory efficacy of MEMH on monosodium urate (MSU) crystals-induced gouty inflammation. MSU crystals stimulated human chondrosarcoma cell line, SW1353, and human primary chondrocytes were treated with MEMH in vitro. The expression levels of pro-inflammatory mediators and metalloproteases were analyzed. The effect of MEMH on NFκB signaling pathway in SW1353 cells was examined. Effect of MEMH on the mRNA expression level of pro-inflammatory mediators and chemotactic factor from human monocytic cell line, THP-1, was also analyzed. The probable role of MEMH in the differentiation process of osteoblast like cells, SaOS-2, after MSU treatment was also observed. To investigate the effects of MEMH in vivo, MSU crystals-induced ankle arthritic model was established. Histopathological changes in affected joints and plasma levels of pro-inflammatory mediators (IL-1β and TNFα) were recorded. MEMH inhibited NFκB signaling pathway and COX-2 protein expression in chondrocytes. MSU-induced mRNA expressions of pro-inflammatory mediators and chemotactic cytokines were suppressed by MEMH. In MSU crystals-induced ankle arthritic mouse model, administration of MEMH relieved inflammatory symptoms and decreased the plasma levels of IL-1β and TNFα. The results indicated that MEMH can effectively inhibit the expression of inflammatory mediators in gouty arthritis, demonstrating its potential for treating gouty arthritis. Copyright © 2017 China Pharmaceutical University. Published by Elsevier B.V. All rights reserved.

Does it pay to be smart, attractive, or confident (or all three)? Relationships among general mental ability, physical attractiveness, core self-evaluations, and income.

PubMed

Judge, Timothy A; Hurst, Charlice; Simon, Lauren S

2009-05-01

The authors investigated core self-evaluations and educational attainment as mediating mechanisms for the influence of appearance (physical attractiveness) and intelligence (general mental ability) on income and financial strain. The direct effects of core self-evaluations on financial strain, as well as the indirect effects through income, were also considered. Longitudinal data were obtained as part of a national study, the Harvard Study of Health and Life Quality, and proposed models were evaluated with structural equation modeling. Results supported a partially mediated model, such that general mental ability and physical attractiveness exhibited both direct and indirect effects on income, as mediated by educational attainment and core self-evaluations. Finally, income negatively predicted financial strain, whereas core self-evaluations had both a direct and an indirect (through income) negative effect on financial strain. Overall, the results suggest that looks (physical attractiveness), brains (intelligence), and personality (core self-evaluations) are all important to income and financial strain. (c) 2009 APA, all rights reserved.

The effect of age on fluid intelligence is fully mediated by physical health.

PubMed

Bergman, Ingvar; Almkvist, Ove

2013-01-01

The present study investigated the extent to which the effect of age on cognitive ability is predicted by individual differences in physical health. The sample consisted of 118 volunteer subjects who were healthy and ranging in age from 26 to 91. The examinations included a clinical investigation, magnetic resonance imaging (MRI) brain neuroimaging, and a comprehensive neuropsychological assessment. The effect of age on fluid IQ with and without visual spatial praxis and on crystallized IQ was tested whether being fully-, partially- or non-mediated by physical health. Structural equation analyses showed that the best and most parsimonious fit to the data was provided by models that were fully mediated for fluid IQ without praxis, non-mediated for crystallized IQ and partially mediated for fluid IQ with praxis. The diseases of the circulatory and nervous systems were the major mediators. It was concluded from the pattern of findings that the effect of age on fluid intelligence is fully mediated by physical health, while crystallized intelligence is non-mediated and visual spatial praxis is partially mediated, influenced mainly by direct effects of age. Our findings imply that improving health by acting against the common age-related circulatory- and nervous system diseases and risk factors will oppose the decline in fluid intelligence with age. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

Overweight, body image, and depression in Asian and Hispanic adolescents.

PubMed

Xie, Bin; Unger, Jennifer B; Gallaher, Peggy; Johnson, C Anderson; Wu, Qiaobing; Chou, Chih-Ping

2010-01-01

To prospectively investigate associations between overweight and depressive symptoms in Asian and Hispanic adolescents. Data included 780 Hispanic and 375 Asian students. Structural equation model was used to prospectively explore moderation effects of gender, ethnicity, and acculturation on associations of overweight, body image dissatisfaction, and depressive symptoms. Significant mediation effect was found only in Asian girls (mediation effect = 0.16, P < 0.05) and girls with high acculturation (mediation effect = 0.17, P < 0.05). Overweight significantly predicted higher body image dissatisfaction, which in turn was significantly related to depressive symptoms. Our findings help understanding the association of overweight and experience of depressive symptoms.

Modeling the Longitudinal Direct and Indirect Effects of Attitudes, Self-Efficacy, and Behavioral Intentions on Practice Behavior Outcomes of Suicide Intervention Training.

PubMed

Osteen, Philip; Frey, Jodi M; Woods, MaKenna N; Ko, Jungyai; Shipe, Stacey

2017-08-01

The purpose of this study was to use a longitudinal path analysis to test attitudes toward suicide prevention, self-efficacy, and behavioral intentions as mediators/moderators of clinical skill development over time following suicide intervention training. Results support a direct effect of attitudes on practice behaviors and self-efficacy, but no moderating effect. Self-efficacy performed as a mediator of practice behaviors over time. Behavioral intention had a direct effect on practice behaviors and mediated the relationship between attitudes and practice behaviors. Implications for research and practice are discussed. © 2016 The American Association of Suicidology.

Cancer literacy as a mediator for cancer screening behaviour in Korean adults.

PubMed

Lee, Hee Yun; Rhee, Taeho Greg; Kim, Nam Keol

2016-09-01

This study investigates the cancer literacy level in Korean adults and examines whether cancer literacy plays a mediating role in the relationship between population characteristics and cancer screening behaviours. We collected data from 585 community-dwelling adults in Korea using self-administered surveys and face-to-face interviews from October to December in 2009. Guided by Andersen's behavioural model, we used a structural equation model to estimate the effect of cancer literacy as a mediator and found that cancer literacy mediated cancer screening behaviour. In the individual path analysis models, cancer literacy played a significant mediating role for the use of eastern medicine, fatalism, health status and the number of chronic diseases. When controlling for other relevant covariates, we found that in the optimal path model, cancer literacy played a mediating role in the relationship between the use of eastern medicine and self-rated health status as well as cancer screening behaviour. Thus, developing community-based cancer education programmes and training clinical practitioners in eastern medicine clinics about the importance of informing their patients about regular cancer screening may be an option to boost cancer literacy and screening behaviour in Korea. © 2015 John Wiley & Sons Ltd.

Gang Membership, School Violence, and the Mediating Effects of Risk and Protective Behaviors in California High Schools

ERIC Educational Resources Information Center

Estrada, Joey Nuñez, Jr.; Gilreath, Tamika D.; Astor, Ron Avi; Benbenishty, Rami

2014-01-01

There is insufficient empirical evidence exploring associations between gang membership and school violence behaviors. Using a sample of 272,863 high school students, this study employs a structural equation model to examine how school risk and protective behaviors and attitudes mediate effects of gang members' involvement with school violence…

Under What Assumptions Do Site-by-Treatment Instruments Identify Average Causal Effects?

ERIC Educational Resources Information Center

Reardon, Sean F.; Raudenbush, Stephen W.

2011-01-01

The purpose of this paper is to clarify the assumptions that must be met if this--multiple site, multiple mediator--strategy, hereafter referred to as "MSMM," is to identify the average causal effects (ATE) in the populations of interest. The authors' investigation of the assumptions of the multiple-mediator, multiple-site IV model demonstrates…

Relationship between mediation analysis and the structured life course approach

PubMed Central

Howe, Laura D; Smith, Andrew D; Macdonald-Wallis, Corrie; Anderson, Emma L; Galobardes, Bruna; Lawlor, Debbie A; Ben-Shlomo, Yoav; Hardy, Rebecca; Cooper, Rachel; Tilling, Kate; Fraser, Abigail

2016-01-01

Abstract Many questions in life course epidemiology involve mediation and/or interaction because of the long latency period between exposures and outcomes. In this paper, we explore how mediation analysis (based on counterfactual theory and implemented using conventional regression approaches) links with a structured approach to selecting life course hypotheses. Using theory and simulated data, we show how the alternative life course hypotheses assessed in the structured life course approach correspond to different combinations of mediation and interaction parameters. For example, an early life critical period model corresponds to a direct effect of the early life exposure, but no indirect effect via the mediator and no interaction between the early life exposure and the mediator. We also compare these methods using an illustrative real-data example using data on parental occupational social class (early life exposure), own adult occupational social class (mediator) and physical capability (outcome). PMID:27681097

Mediation Analysis: A Practitioner's Guide.

PubMed

VanderWeele, Tyler J

2016-01-01

This article provides an overview of recent developments in mediation analysis, that is, analyses used to assess the relative magnitude of different pathways and mechanisms by which an exposure may affect an outcome. Traditional approaches to mediation in the biomedical and social sciences are described. Attention is given to the confounding assumptions required for a causal interpretation of direct and indirect effect estimates. Methods from the causal inference literature to conduct mediation in the presence of exposure-mediator interactions, binary outcomes, binary mediators, and case-control study designs are presented. Sensitivity analysis techniques for unmeasured confounding and measurement error are introduced. Discussion is given to extensions to time-to-event outcomes and multiple mediators. Further flexible modeling strategies arising from the precise counterfactual definitions of direct and indirect effects are also described. The focus throughout is on methodology that is easily implementable in practice across a broad range of potential applications.

Understanding catastrophizing from a misdirected problem-solving perspective.

PubMed

Flink, Ida K; Boersma, Katja; MacDonald, Shane; Linton, Steven J

2012-05-01

The aim is to explore pain catastrophizing from a problem-solving perspective. The links between catastrophizing, problem framing, and problem-solving behaviour are examined through two possible models of mediation as inferred by two contemporary and complementary theoretical models, the misdirected problem solving model (Eccleston & Crombez, 2007) and the fear-anxiety-avoidance model (Asmundson, Norton, & Vlaeyen, 2004). In this prospective study, a general population sample (n= 173) with perceived problems with spinal pain filled out questionnaires twice; catastrophizing and problem framing were assessed on the first occasion and health care seeking (as a proxy for medically oriented problem solving) was assessed 7 months later. Two different approaches were used to explore whether the data supported any of the proposed models of mediation. First, multiple regressions were used according to traditional recommendations for mediation analyses. Second, a bootstrapping method (n= 1000 bootstrap resamples) was used to explore the significance of the indirect effects in both possible models of mediation. The results verified the concepts included in the misdirected problem solving model. However, the direction of the relations was more in line with the fear-anxiety-avoidance model. More specifically, the mediation analyses provided support for viewing catastrophizing as a mediator of the relation between biomedical problem framing and medically oriented problem-solving behaviour. These findings provide support for viewing catastrophizing from a problem-solving perspective and imply a need to examine and address problem framing and catastrophizing in back pain patients. ©2011 The British Psychological Society.

Understanding causal pathways within health systems policy evaluation through mediation analysis: an application to payment for performance (P4P) in Tanzania.

PubMed

Anselmi, Laura; Binyaruka, Peter; Borghi, Josephine

2017-02-02

The evaluation of payment for performance (P4P) programmes has focused mainly on understanding contributions to health service coverage, without unpacking causal mechanisms. The overall aim of the paper is to test the causal pathways through which P4P schemes may (or may not) influence maternal care outcomes. We used data from an evaluation of a P4P programme in Tanzania. Data were collected from a sample of 3000 women who delivered in the 12 months prior to interview and 200 health workers at 150 health facilities from seven intervention and four comparison districts in Tanzania in January 2012 and in February 2013. We applied causal mediation analysis using a linear structural equation model to identify direct and indirect effects of P4P on institutional delivery rates and on the uptake of two doses of an antimalarial drug during pregnancy. We first ran a series of linear difference-in-difference regression models to test the effect of P4P on potential mediators, which we then included in a linear difference-in-difference model evaluating the impact of P4P on the outcome. We tested the robustness of our results to unmeasured confounding using semi-parametric methods. P4P reduced the probability of women paying for delivery care (-4.5 percentage points) which mediates the total effect of P4P on institutional deliveries (by 48%) and on deliveries in a public health facility (by 78%). P4P reduced the stock-out rate for some essential drugs, specifically oxytocin (-36 percentage points), which mediated the total effect of P4P on institutional deliveries (by 22%) and deliveries in a public health facility (by 30%). P4P increased kindness at delivery (5 percentage points), which mediated the effect of P4P on institutional deliveries (by 48%) and on deliveries in a public health facility (by 49%). P4P increased the likelihood of supervision visits taking place within the last 90 days (18 percentage points), which mediated 15% of the total P4P effect on the uptake of two antimalarial doses during antenatal care (IPT2). Kindness during deliveries and the probability of paying out of pocket for delivery care were the mediators most robust to unmeasured confounding. The effect of P4P on institutional deliveries is mediated by financing and human resources factors, while uptake of antimalarials in pregnancy is mediated by governance factors. Further research is required to explore additional and more complex causal pathways.

Comparing Indirect Effects in SEM: A Sequential Model Fitting Method Using Covariance-Equivalent Specifications

ERIC Educational Resources Information Center

Chan, Wai

2007-01-01

In social science research, an indirect effect occurs when the influence of an antecedent variable on the effect variable is mediated by an intervening variable. To compare indirect effects within a sample or across different samples, structural equation modeling (SEM) can be used if the computer program supports model fitting with nonlinear…

Structural Equation Modeling of Retention and Overage Effects on Dropping Out of School.

ERIC Educational Resources Information Center

Grissom, James B.; Shepard, Lorrie A.

This study addresses the effect that grade retention has on dropping out of school. A structural model was developed to test the effect of grade retention on dropping out while controlling for the effects of other possible mediating variables, especially achievement. This model with slight modifications was applied across four different school…

Mediating role of borderline personality disorder traits in the effects of childhood maltreatment on suicidal behaviour among mood disorder patients.

PubMed

Aaltonen, K I; Rosenström, T; Baryshnikov, I; Karpov, B; Melartin, T; Suominen, K; Heikkinen, M; Näätänen, P; Koivisto, M; Joffe, G; Isometsä, E

2017-07-01

Substantial evidence supports an association between childhood maltreatment and suicidal behaviour. However, few studies have examined factors mediating this relationship among patients with unipolar or bipolar mood disorders. Depressive disorder and bipolar disorder (ICD-10-DCR) patients (n=287) from the Helsinki University Psychiatric Consortium (HUPC) Study were surveyed on self-reported childhood experiences, current depressive symptoms, borderline personality disorder traits, and lifetime suicidal behaviour. Psychiatric records served to complement the information on suicide attempts. We examined by formal mediation analyses whether (1) the effect of childhood maltreatment on suicidal behaviour is mediated through borderline personality disorder traits and (2) the mediation effect differs between lifetime suicidal ideation and lifetime suicide attempts. The impact of childhood maltreatment in multivariate models on either lifetime suicidal ideation or lifetime suicide attempts showed comparable total effects. In formal mediation analyses, borderline personality disorder traits mediated all of the total effect of childhood maltreatment on lifetime suicide attempts, but only one fifth of the total effect on lifetime suicidal ideation. The mediation effect was stronger for lifetime suicide attempts than for lifetime suicidal ideation (P=0.002) and independent of current depressive symptoms. The mechanisms of the effect of childhood maltreatment on suicidal ideation versus suicide attempts may diverge among psychiatric patients with mood disorders. Borderline personality disorder traits may contribute to these mechanisms, although the influence appears considerably stronger for suicide attempts than for suicidal ideation. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

Studies of transformational leadership in the consumer service workgroup: cooperative conflict resolution and the mediating roles of job satisfaction and change commitment.

PubMed

Yang, Yi-Feng

2012-10-01

The present paper evaluates the effect of transformational leadership on job satisfaction and change commitment along with their interconnected effects (mediation) on cooperative conflict resolution (management) in customer service activities in Taiwan. The multi-source samples consist of data from personnel serving at customer centers (workgroups), such as phone service personnel, customer representatives, financial specialists, and front-line salespeople. An empirical study was carried out using a multiple mediation procedure incorporating boot-strapping techniques and PRODCLIN2 with structural equation modeling (SEM) analysis. The results indicate that the main effect of the leadership style on cooperative conflict resolution is mediated by change commitment and job satisfaction.

The mediating role of coping strategy in the association between family functioning and nonsuicidal self-injury among Taiwanese adolescents.

PubMed

Ren, Yaxuan; Lin, Min-Pei; Liu, Yin-Han; Zhang, Xu; Wu, Jo Yung-Wei; Hu, Wei-Hsuan; Xu, Sian; You, Jianing

2018-01-22

Nock's (2009) integrated theoretical model suggests that both intrapersonal and interpersonal factors contribute to the development of nonsuicidal self-injury (NSSI). Based on this model, the present study examined the roles of family functioning and coping strategy in predicting NSSI, as well as the mediating effect of coping strategy in the relationship between family functioning and NSSI. Gender differences on the associations of these variables were also examined. A sample of 1,989 secondary school students (52.0% females) in Taiwan was assessed by self-report measures of perceived family functioning, coping strategy, and NSSI. Results showed that both family functioning and avoidance/emotion-focused coping strategy predicted NSSI. Additionally, the association between family functioning and NSSI was mediated by avoidance/emotion-focused coping strategy. Gender differences were not found on the associations among these study variables. These data provided evidences that the Nock's (2009) integrated theoretical model may help to explain how coping strategy mediates the effect of family functioning on NSSI. The implications of the findings for future research and intervention were discussed. © 2018 Wiley Periodicals, Inc.

Tests of Mediation: Paradoxical Decline in Statistical Power as a Function of Mediator Collinearity

PubMed Central

Beasley, T. Mark

2013-01-01

Increasing the correlation between the independent variable and the mediator (a coefficient) increases the effect size (ab) for mediation analysis; however, increasing a by definition increases collinearity in mediation models. As a result, the standard error of product tests increase. The variance inflation due to increases in a at some point outweighs the increase of the effect size (ab) and results in a loss of statistical power. This phenomenon also occurs with nonparametric bootstrapping approaches because the variance of the bootstrap distribution of ab approximates the variance expected from normal theory. Both variances increase dramatically when a exceeds the b coefficient, thus explaining the power decline with increases in a. Implications for statistical analysis and applied researchers are discussed. PMID:24954952

Attachment, emotion regulation, and adaptation to breast cancer: assessment of a mediational hypothesis.

PubMed

Ávila, Marisa; Brandão, Tânia; Teixeira, Joana; Coimbra, Joaquim Luis; Matos, Paula Mena

2015-11-01

This study examines the links between attachment, adaptation to breast cancer, and the mediating role played by emotional regulation processes. Participants were 127 women with breast cancer recruited in two public hospitals of Porto and at the Portuguese Cancer League. Women completed measures of attachment, quality of life, and emotion regulation. Path models were used to examine the associations between the constructs and to test the mediational hypotheses. Significant associations were found between attachment and adaptation. Dimensions of emotion regulation totally or partially mediated the associations between attachment and adaptation outcomes. Attachment security effects on interpersonal relations were totally mediated by communicating emotions. Also, attachment anxiety effect on physical well-being was totally mediated by rumination. Attachment avoidance effects on psychological outcomes were totally mediated by emotional control and partially mediated by communicating emotions for the case of interpersonal relations. This study highlights the importance of addressing emotional regulation jointly with attachment to deepen the comprehension of the relational processes implicated in adaptation to breast cancer. Results supported a mediational hypothesis, presenting emotional regulation processes as relevant dimensions for the understanding of attachment associations with adaptation to breast cancer. Copyright © 2015 John Wiley & Sons, Ltd.

Effects of Angelica gigas Nakai as an Anti-Inflammatory Agent in In Vitro and In Vivo Atopic Dermatitis Models

PubMed Central

Ok, Seon; Oh, Sa-Rang; Jung, Tae-Sung; Jeon, Sang-Ok; Jung, Ji-wook

2018-01-01

We investigated the cellular and molecular mechanisms mediating the effects of Angelica gigas Nakai extract (AGNE) through the mitogen-activated protein kinases (MAPKs)/NF-κB pathway using in vitro and in vivo atopic dermatitis (AD) models. We examined the effects of AGNE on the expression of proinflammatory cytokines and chemokines in human mast cell line-1 (HMC-1) cells. Compound 48/80-induced pruritus and 2,4-dinitrochlorobenzene- (DNCB-) induced AD-like skin lesion mouse models were also used to investigate the antiallergic effects of AGNE. AGNE reduced histamine secretion, production of proinflammatory cytokines including interleukin- (IL-) 1β, IL-4, IL-6, IL-8, and IL-10, and expression of cyclooxygenase- (COX-) 2 in HMC-1 cells. Scratching behavior and DNCB-induced AD-like skin lesions were also attenuated by AGNE administration through the reduction of serum IgE, histamine, tumor necrosis factor-α (TNF-α), IL-6 levels, and COX-2 expression in skin tissue from mouse models. Furthermore, these inhibitory effects were mediated by the blockade of the MAPKs and NF-κB pathway. The findings of this study proved that AGNE improves the scratching behavior and atopy symptoms and reduces the activity of various atopy-related mediators in HMC-1 cells and mice model. These results suggest the AGNE has a therapeutic potential in anti-AD. PMID:29713361

Investigating phonon-mediated interactions with polar molecules

NASA Astrophysics Data System (ADS)

Sous, John; Madison, Kirk; Berciu, Mona; Krems, Roman

2017-04-01

We show that an ensemble of polar molecules in an optical lattice realizes the Peierls polaron model for hard-core particles/ pseudospins. We analyze the quasiparticle spectrum in the one-particle subspace, the two-particle subspace and at finite concentrations. We derive an effective model that describes the low-energy behavior of the system. We show that the Hamiltonian includes phonon-mediated repulsions and phonon-mediated ``pair-hopping'' terms which move the particle pair as a whole. We show that microwave excitations of the system exhibit signatures of these interactions. These results pave the way for the experimental observation of phonon-mediated repulsion. This work was supported by NSERC of Canada and the Stewart Blusson Quantum Matter Institute.

The integrated model of sport confidence: a canonical correlation and mediational analysis.

PubMed

Koehn, Stefan; Pearce, Alan J; Morris, Tony

2013-12-01

The main purpose of the study was to examine crucial parts of Vealey's (2001) integrated framework hypothesizing that sport confidence is a mediating variable between sources of sport confidence (including achievement, self-regulation, and social climate) and athletes' affect in competition. The sample consisted of 386 athletes, who completed the Sources of Sport Confidence Questionnaire, Trait Sport Confidence Inventory, and Dispositional Flow Scale-2. Canonical correlation analysis revealed a confidence-achievement dimension underlying flow. Bias-corrected bootstrap confidence intervals in AMOS 20.0 were used in examining mediation effects between source domains and dispositional flow. Results showed that sport confidence partially mediated the relationship between achievement and self-regulation domains and flow, whereas no significant mediation was found for social climate. On a subscale level, full mediation models emerged for achievement and flow dimensions of challenge-skills balance, clear goals, and concentration on the task at hand.

Life stress as a mediator and community belonging as a moderator of mood and anxiety disorders and co-occurring disorders with heavy drinking of gay, lesbian, bisexual, and heterosexual Canadians.

PubMed

Pakula, Basia; Carpiano, Richard M; Ratner, Pamela A; Shoveller, Jean A

2016-08-01

To examine the extent to which sexual identity disparities in mental health outcomes (anxiety disorder, mood disorder, anxiety-mood disorder, and co-occurring anxiety or mood disorder and heavy drinking) are mediated by life stress or moderated by a sense of community belonging. This study pooled data from a large, national, multi-year sample of Canadians aged 18-59 years, who self-identified as lesbian, gay, bisexual, or heterosexual (N = 222,548). A series of stratified binary mediation models were fitted. Significance of the indirect effect was determined by using bootstrapping to obtain standard errors and confidence intervals. Sexual minority (versus heterosexual) respondents were significantly more likely to describe their lives as stressful, their sense of community belonging as weak, and had significantly greater odds of the negative mental health outcomes. Perceived life stress partially mediated the effects of sexual identity on the mental health outcomes. The differences between the mediated effects for the gay/lesbian and bisexual subgroups were statistically significant (all p < 0.05). When stratified by sense of community belonging, life stress mediated the relationship with mood disorders for the gay/lesbian group, where a strong sense of community belonging was associated with greater odds of mood disorders for gay/lesbian versus heterosexual respondents. These mediation and moderated mediation models provide further evidence for a social patterning of the mental health disparities experienced by sexual minorities in Canada.

Short-term mediating factors of a school-based intervention to prevent youth substance use in Europe.

PubMed

Giannotta, Fabrizia; Vigna-Taglianti, Federica; Rosaria Galanti, Maria; Scatigna, Maria; Faggiano, Fabrizio

2014-05-01

To investigate factors mediating the effects of a European school-based intervention (Unplugged) based on a social influence approach to youths' substance use. Schools in seven European countries (n = 143, including 7,079 pupils) were randomly assigned to an experimental condition (Unplugged curriculum) or a control condition (usual health education). Data were collected before (pretest) and 3 months after the end of the program (posttest). Multilevel multiple mediation models were applied to the study of effect mediation separately for tobacco, alcohol, and cannabis use. Analyses were conducted on the whole sample, and separately on baseline users and nonusers of each substance. Compared with the control group, participants in the program endorsed less positive attitudes toward drugs; positive beliefs about cigarettes, alcohol, and cannabis; and the normative perception of peers using tobacco and cannabis. They also increased in knowledge about all substances and refusal skills toward tobacco. Decreased positive attitudes toward drugs, increase in refusal skills, and reappraisal of norms about peer using tobacco and cannabis appeared to mediate the effects of the program on the use of substances. However, mediating effects were generally weak and some of them were only marginally significant. This study lends some support to the notion that school-based programs based on a social influence model may prevent juvenile substance use through the modification of attitudes, refusal skills, and normative perceptions. Copyright © 2014 Society for Adolescent Health and Medicine. Published by Elsevier Inc. All rights reserved.

Linking Family Economic Hardship to Early Childhood Health: An Investigation of Mediating Pathways.

PubMed

Hsu, Hui-Chin; Wickrama, Kandauda A S

2015-12-01

The underlying mechanisms through which family economic adversity influences child health are less understood. Taking a process-oriented approach, this study examined maternal mental health and investment in children, child health insurance, and child healthcare as mediators linking family economic hardship (FEH) to child health. A structural equation modeling was applied to test the hypothesized mediating model. After adjustment for sociodemographic risk factors, results revealed: (1) a significant direct path linking FEH to poor child health (effect size = .372), and (2) six significant mediating pathways (total effect size = .089). In two mediating pathways, exposures to FEH undermined mothers' mental health: in the first pathway poor maternal mental health led to decreased parental investment, which, in turn, contributed to poor child health, whereas in the second pathway the adverse effect of poor maternal mental health was cascaded through child unmet healthcare need, which resulted in poor child health. One pathway involved child insurance status, where the effect of FEH increased the likelihood to be uninsured, which led to unmet healthcare need, and, in turn, to poor health. Three pathways involved preventive care: in one pathway FEH contributed to poor preventive care, which led to unmet healthcare need and then to poor health; in the other two pathways where poor preventive care respectively gave rise to decreased investment in children or poor maternal mental health, which further contributed to poor child health. Results suggest that the association between FEH and children's health is mediated by multiple pathways.

The Effect of Environmental Regulation on Employment in Resource-Based Areas of China-An Empirical Research Based on the Mediating Effect Model.

PubMed

Cao, Wenbin; Wang, Hui; Ying, Huihui

2017-12-19

While environmental pollution is becoming more and more serious, many countries are adopting policies to control pollution. At the same time, the environmental regulation will inevitably affect economic and social development, especially employment growth. The environmental regulation will not only affect the scale of employment directly, but it will also have indirect effects by stimulating upgrades in the industrial structure and in technological innovation. This paper examines the impact of environmental regulation on employment, using a mediating model based on the data from five typical resource-based provinces in China from 2000 to 2015. The estimation is performed based on the system GMM (Generalized Method of Moments) estimator. The results show that the implementation of environmental regulation in resource-based areas has both a direct effect and a mediating effect on employment. These findings provide policy implications for these resource-based areas to promote the coordinating development between the environment and employment.

The Effect of Environmental Regulation on Employment in Resource-Based Areas of China—An Empirical Research Based on the Mediating Effect Model

PubMed Central

Cao, Wenbin; Wang, Hui; Ying, Huihui

2017-01-01

While environmental pollution is becoming more and more serious, many countries are adopting policies to control pollution. At the same time, the environmental regulation will inevitably affect economic and social development, especially employment growth. The environmental regulation will not only affect the scale of employment directly, but it will also have indirect effects by stimulating upgrades in the industrial structure and in technological innovation. This paper examines the impact of environmental regulation on employment, using a mediating model based on the data from five typical resource-based provinces in China from 2000 to 2015. The estimation is performed based on the system GMM (Generalized Method of Moments) estimator. The results show that the implementation of environmental regulation in resource-based areas has both a direct effect and a mediating effect on employment. These findings provide policy implications for these resource-based areas to promote the coordinating development between the environment and employment. PMID:29257068

Caenorhabditis elegans as a Model to Study the Molecular and Genetic Mechanisms of Drug Addiction

PubMed Central

Engleman, Eric A.; Katner, Simon N.; Neal-Beliveau, Bethany S.

2016-01-01

Drug addiction takes a massive toll on society. Novel animal models are needed to test new treatments and understand the basic mechanisms underlying addiction. Rodent models have identified the neurocircuitry involved in addictive behavior and indicate that rodents possess some of the same neurobiologic mechanisms that mediate addiction in humans. Recent studies indicate that addiction is mechanistically and phylogenetically ancient and many mechanisms that underlie human addiction are also present in invertebrates. The nematode Caenorhabditis elegans has conserved neurobiologic systems with powerful molecular and genetic tools and a rapid rate of development that enables cost-effective translational discovery. Emerging evidence suggests that C. elegans is an excellent model to identify molecular mechanisms that mediate drug-induced behavior and potential targets for medications development for various addictive compounds. C. elegans emit many behaviors that can be easily quantitated including some that involve interactions with the environment. Ethanol (EtOH) is the best-studied drug-of-abuse in C. elegans and at least 50 different genes/targets have been identified as mediating EtOH’s effects and polymorphisms in some orthologs in humans are associated with alcohol use disorders. C. elegans has also been shown to display dopamine and cholinergic system–dependent attraction to nicotine and demonstrate preference for cues previously associated with nicotine. Cocaine and methamphetamine have been found to produce dopamine-dependent reward-like behaviors in C. elegans. These behavioral tests in combination with genetic/molecular manipulations have led to the identification of dozens of target genes/systems in C. elegans that mediate drug effects. The one target/gene identified as essential for drug-induced behavioral responses across all drugs of abuse was the cat-2 gene coding for tyrosine hydroxylase, which is consistent with the role of dopamine neurotransmission in human addiction. Overall, C. elegans can be used to model aspects of drug addiction and identify systems and molecular mechanisms that mediate drug effects. The findings are surprisingly consistent with analogous findings in higher-level organisms. Further, model refinement is warranted to improve model validity and increase utility for medications development. PMID:26810004

Caenorhabditis elegans as a Model to Study the Molecular and Genetic Mechanisms of Drug Addiction.

PubMed

Engleman, Eric A; Katner, Simon N; Neal-Beliveau, Bethany S

2016-01-01

Drug addiction takes a massive toll on society. Novel animal models are needed to test new treatments and understand the basic mechanisms underlying addiction. Rodent models have identified the neurocircuitry involved in addictive behavior and indicate that rodents possess some of the same neurobiologic mechanisms that mediate addiction in humans. Recent studies indicate that addiction is mechanistically and phylogenetically ancient and many mechanisms that underlie human addiction are also present in invertebrates. The nematode Caenorhabditis elegans has conserved neurobiologic systems with powerful molecular and genetic tools and a rapid rate of development that enables cost-effective translational discovery. Emerging evidence suggests that C. elegans is an excellent model to identify molecular mechanisms that mediate drug-induced behavior and potential targets for medications development for various addictive compounds. C. elegans emit many behaviors that can be easily quantitated including some that involve interactions with the environment. Ethanol (EtOH) is the best-studied drug-of-abuse in C. elegans and at least 50 different genes/targets have been identified as mediating EtOH's effects and polymorphisms in some orthologs in humans are associated with alcohol use disorders. C. elegans has also been shown to display dopamine and cholinergic system-dependent attraction to nicotine and demonstrate preference for cues previously associated with nicotine. Cocaine and methamphetamine have been found to produce dopamine-dependent reward-like behaviors in C. elegans. These behavioral tests in combination with genetic/molecular manipulations have led to the identification of dozens of target genes/systems in C. elegans that mediate drug effects. The one target/gene identified as essential for drug-induced behavioral responses across all drugs of abuse was the cat-2 gene coding for tyrosine hydroxylase, which is consistent with the role of dopamine neurotransmission in human addiction. Overall, C. elegans can be used to model aspects of drug addiction and identify systems and molecular mechanisms that mediate drug effects. The findings are surprisingly consistent with analogous findings in higher-level organisms. Further, model refinement is warranted to improve model validity and increase utility for medications development. Copyright © 2016. Published by Elsevier Inc.

Participation in Organized Activities and Conduct Problems in Elementary School: The Mediating Effect of Social Skills

ERIC Educational Resources Information Center

Denault, Anne-Sophie; Déry, Michèle

2015-01-01

The goal of this study was to test a mediation model in which social skills mediate the relationship between participation in organized activities and conduct problems among elementary school children. Two moderators of these associations were also examined, namely, gender and reception of special education services. A total of 563 children (45%…

The Rights and Freedoms Gradient of Health: Evidence from a Cross-National Study

PubMed Central

Bezo, Brent; Maggi, Stefania; Roberts, William L.

2012-01-01

This study examined the combined influences of national levels of socioeconomic status (SES), social capital, and rights and freedoms on population level physical and mental health outcomes. Indicators of mental health were suicide rates, alcohol consumption, and tobacco use. Indicators of physical health included life expectancy, infant mortality rates, and prevalence of HIV. Using pathway analysis on international data from a selected sample of European, North American, South American, and South Caucasus countries, similar models for mental health and physical health were developed. In the first model, the positive effects of SES and social capital on physical health were completely mediated via rights and freedoms. In the second model, the positive effect of SES on mental health was completely mediated, while the impact of social capital was partially mediated through rights and freedoms. We named the models, the “rights and freedoms gradient of health” in recognition of this latter construct’s crucial role in determining both physical and mental health. PMID:23162498

An Experimental Test of the Contingency Model of Leadership Effectiveness.

ERIC Educational Resources Information Center

Chemers, Martin M.; Skrzypek, George J.

The present experiment provided a test of Fiedler's (1967) Contingency Model of Leadership Effectiveness, i.e., the relationship of leader style to group effectiveness is mediated by situational demands. Thirty-two 4 man task groups composed of military academy cadets were run in the experiment. In accordance with the Contingency Model, leaders…

Attributional style as a mediator between parental abuse risk and child internalizing symptomatology.

PubMed

Rodriguez, Christina M

2006-05-01

This study examined a model wherein children's attributional style mediates the relationship between parental physical child-abuse risk and children's internalizing problems. Using structural equation modeling, three indices of abuse risk were selected (child abuse potential, physical discipline use, and dysfunctional parenting style) and two indices of children's internalizing problems (depression and anxiety). The sample included 75 parent-child dyads, in which parents reported on their abuse risk and children independently completed measures of depressive and anxious symptomatology and a measure on their attributional style. Findings supported the model that children's attributional style for positive events (but not negative events) partially mediated the relationship between abuse risk and internalizing symptoms, with significant direct and indirect effects of abuse risk on internalizing symptomatology. Future directions to continue evaluating additional mediators and other possible contextual variables are discussed.

The cognitive mediation model: factors influencing public knowledge of the H1N1 pandemic and intention to take precautionary behaviors.

PubMed

Ho, Shirley S; Peh, Xianghong; Soh, Veronica W L

2013-01-01

This study uses the cognitive mediation model as the theoretical framework to examine the influence of motivations, communication, and news elaboration on public knowledge of the H1N1 pandemic and the intention to take precautionary behaviors in Singapore. Using a nationally representative random digit dialing telephone survey of 1,055 adult Singaporeans, the authors' results show that the cognitive mediation model can be applied to health contexts, in which motivations (surveillance gratification, guidance, and need for cognition) were positively associated with news attention, elaboration, and interpersonal communication. News attention, elaboration, and interpersonal communication in turn positively influence public knowledge about the H1N1 influenza. In addition, results show that the motivations have significant indirect effects on behavioral intentions, as partially mediated by communication (media attention and interpersonal communication), elaboration, and knowledge. The authors conclude that the cognitive mediation model can be extended to behavioral outcomes, above and beyond knowledge. Implications for theory and practice for health communication were discussed.

Mechanism of Developmental Change in the PLAY Project Home Consultation Program: Evidence from a Randomized Control Trial.

PubMed

Mahoney, Gerald; Solomon, Richard

2016-05-01

This investigation is a secondary analysis of data from a randomized control trial of the PLAY Home Consultation Intervention Program which was conducted with 112 preschool children with Autism Spectrum Disorders and their parents (Solomon et al. in J Dev Behav Pediatr 35:475-485, 2014). Subjects were randomly assigned to either a community standard (CS) treatment group or to the PLAY Project plus CS Treatment (PLAY). PLAY subjects received monthly parent-child intervention sessions for 1 year during which parents learned how to use the rationale and interactive strategies of the Developmental, Individual-differences, Relationship-based (DIR) intervention model (Greenspan and Weider in The child with special needs: encouraging intellectual and emotional growth. DeCapo Press, Cambridge, MA, 1998) to engage in more responsive, affective and less directive interactions with their children. This investigation examined whether PLAY intervention effects on parents' style of interacting with their children as well as on children's social engagement mediated the effects of PLAY on children's autism severity as measured by ADOS calibrated severity scores. Regression procedures were used to test for mediation. There were two main findings. First the effects of PLAY on children's social engagement were mediated by the increases in parental responsiveness and affect that were promoted by PLAY. Second, the effects of PLAY on the severity children's Social Affect disorders were mediated by changes in parental responsiveness and affect; however, the effects of Responsive/Affect were mediated by the impact these variables had on children's social engagement. Results are discussed in terms of contemporary models of developmental change including the developmental change model that is the foundation for DIR.

Childhood trauma and eating psychopathology: a mediating role for dissociation and emotion dysregulation?

PubMed

Moulton, Stuart J; Newman, Emily; Power, Kevin; Swanson, Vivien; Day, Kenny

2015-01-01

The present study examined the relationship between different forms of childhood trauma and eating psychopathology using a multiple mediation model that included emotion dysregulation and dissociation as hypothesised mediators. 142 female undergraduate psychology students studying at two British Universities participated in this cross-sectional study. Participants completed measures of childhood trauma (emotional abuse, physical abuse, sexual abuse, emotional neglect and physical neglect), eating psychopathology, dissociation and emotion dysregulation. Multiple mediation analysis was conducted to investigate the study's proposed model. Results revealed that the multiple mediation model significantly predicted eating psychopathology. Additionally, both emotion dysregulation and dissociation were found to be significant mediators between childhood trauma and eating psychopathology. A specific indirect effect was observed between childhood emotional abuse and eating psychopathology through emotion dysregulation. Findings support previous research linking childhood trauma to eating psychopathology. They indicate that multiple forms of childhood trauma should be assessed for individuals with eating disorders. The possible maintaining role of emotion regulation processes should also be considered in the treatment of eating disorders. Copyright © 2014 Elsevier Ltd. All rights reserved.

Role of religious involvement and spirituality in functioning among African Americans with cancer: testing a mediational model

PubMed Central

Holt, Cheryl L.; Wang, Min Qi; Caplan, Lee; Schulz, Emily; Blake, Victor; Southward, Vivian L.

2013-01-01

The present study tested a mediational model of the role of religious involvement, spirituality, and physical/emotional functioning in a sample of African American men and women with cancer. Several mediators were proposed based on theory and previous research, including sense of meaning, positive and negative affect, and positive and negative religious coping. One hundred patients were recruited through oncologist offices, key community leaders and community organizations, and interviewed by telephone. Participants completed an established measure of religious involvement, the Functional Assessment of Chronic Illness Therapy-Spiritual Well-Being Scale (FACIT-SP-12 version 4), the Positive and Negative Affect Schedule (PANAS), the Meaning in Life Scale, the Brief RCOPE, and the SF-12, which assesses physical and emotional functioning. Positive affect completely mediated the relationship between religious behaviors and emotional functioning. Though several other constructs showed relationships with study variables, evidence of mediation was not supported. Mediational models were not significant for the physical functioning outcome, nor were there significant main effects of religious involvement or spirituality for this outcome. Implications for cancer survivorship interventions are discussed. PMID:21222026

A multiple mediational test of the relationship between childhood maltreatment and non-suicidal self-injury.

PubMed

Shenk, Chad E; Noll, Jennie G; Cassarly, Jennifer A

2010-04-01

Post-traumatic stress symptoms, depressive symptoms, and psychological dysregulation have been shown to mediate the relationship between child maltreatment and non-suicidal self-injury. However, these proposed mediators often co-occur and previous research has not tested mediation when all variables are assessed simultaneously. The current study sought to advance the literature on maltreatment and self-injury by estimating the mediational effects of post-traumatic stress symptoms, depressive symptoms, and psychological dysregulation in the same multiple mediator model. Both maltreated (n = 129) and non-maltreated (n = 82) adolescent females, consisting of Caucasian (55%), African-American (37%), and Bi-racial (8%) backgrounds, participated in the study. Results indicated that only post-traumatic stress symptoms mediated the relationship between maltreatment and self-injury when all variables were included in the model. Overall, post-traumatic symptoms represented a unique pathway from maltreatment to self-injury and warrant special attention when assessing and treating such behavior with adolescent females.

Does competence mediate the associations between puberty and internalizing or externalizing problems in adolescent girls?

PubMed

Negriff, Sonya; Hillman, Jennifer B; Dorn, Lorah D

2011-10-01

To examine separate mediational models linking (a) menarcheal status or (b) pubertal timing to internalizing and externalizing problems through competence. This study involved cross-sectional analyses of 262 adolescent girls (age: 11-17 years; mean = 14.93, standard deviation = 2.17) enrolled in a longitudinal study examining the association of psychological functioning and smoking with reproductive and bone health. Measures of menarcheal status (pre/post), pubertal timing (early, on-time, or late), internalizing and externalizing behavior, and perceived competence (parent and adolescent report) were obtained. Structural equation modeling was used for analyses. Perceived competence was found to fully mediate the association between menarcheal status and parent report of internalizing and externalizing problems. For adolescent report, there was a full mediation effect for internalizing problems but a partial mediation effect for externalizing problems. Being menarcheal was related to lower competence, which was in turn related to higher internalizing and externalizing problems. Models including pubertal timing were not significant. Perceived competence is important in understanding the associations between menarcheal status and internalizing and externalizing problems. Interventions targeting competence, particularly in postmenarcheal girls, may reduce or prevent problem behaviors. Copyright © 2011 Society for Adolescent Health and Medicine. Published by Elsevier Inc. All rights reserved.

Coping as a mechanism linking stressful life events and mental health problems in adolescents.

PubMed

Meng, Xiu Hong; Tao, Fang Biao; Wan, Yu Hui; Hu, Yan; Wang, Ren Xi

2011-12-01

Although stressful life events represent an etiologic factor of mental health problems in adolescents, few studies have been conducted to address mechanisms linking the stress-psychopathology relation. The present study was designed to examine coping as a mediate factor on the relationship between stressful life events and symptoms of anxiety and depression. The participants were 13 512 students from eight cities of China, who participated in a school-based survey. Data were collected by a questionnaire comprising coping, stressful life events, anxiety, and depressive symptoms. As a model, a series of regression equations were used to examine whether coping mediated the association between stressful life events and symptoms of anxiety and depression. Each dimension of stressful life events showed significant correlation with anxiety, depression and coping (all P<0.001). In the model to analyze mediate effects, all standardized coefficients (β) were significant (all P<0.01), indicating marked mediator effects. Furthermore, negative coping might account for more mediate effects than positive coping on this relationship. Coping partially mediated the relationship between stressful life events and mental health during adolescence. This study highlighted an important public health priority for preventive interventions targeting stress-related psychopathology, and for further promoting adolescents' mental health. Copyright © 2011 The Editorial Board of Biomedical and Environmental Sciences. Published by Elsevier B.V. All rights reserved.

Influence of body condition on the population dynamics of Atlantic salmon with consideration of the potential impact of sea lice.

PubMed

Susdorf, R; Salama, N K G; Lusseau, D

2017-11-21

Atlantic salmon Salmo salar is an iconic species of high conservation and economic importance. At sea, individuals typically are subject to sea lice infestation, which can have detrimental effects on their host. Over recent decades, the body condition and marine survival in NE Atlantic stocks have generally decreased, reflected in fewer adults returning to rivers, which is partly attributable to sea lice. We developed a deterministic stage-structured population model to assess condition-mediated population dynamics resulting in changing fecundity, age at sexual maturation and marine survival rate. The model is parameterized using data from the North Esk system, north-east Scotland. Both constant and density-dependent juvenile survival rates are considered. We show that even small sea lice-mediated changes in mean body condition of MSW can cause substantial population declines, whereas 1SW condition is less influential. Density dependence alleviates the condition-mediated population effect. The resilience of the population to demographic perturbations declines as adult condition is reduced. Indirect demographic changes in salmonid life-history traits (e.g., body condition) are often considered unimportant for population trajectory. The model shows that Atlantic salmon population dynamics can be highly responsive to sea lice-mediated effects on adult body condition, thus highlighting the importance of non-lethal parasitic long-term effects. © 2017 The Authors Journal of Fish Diseases Published by John Wiley & Sons Ltd.

The relation between perceived parental involvement and academic achievement: the roles of Taiwanese students' academic beliefs and filial piety.

PubMed

Chen, Wei-Wen; Ho, Hsiu-Zu

2012-01-01

The excellent academic performance among East-Asian students has drawn international attention from educators and psychologists. However, the process that underlies student academic achievement for this particular group has rarely been documented. The present study examines how the relation between perceived parental involvement and Taiwanese students' academic achievement is mediated by student academic beliefs (i.e., beliefs about effort, academic self-concept, and perceived control). The study further explores whether this mediating effect varies with types of filial piety. Participants were 468 first-year students from colleges and universities in Taiwan. Multiple-group mediating models were analyzed using structural equation modeling (SEM). Results indicated that, for the Taiwanese sample, students' academic beliefs mediated the relation between perceived parental involvement and academic achievement. Furthermore, the mediational effect was significant for the reciprocal filial type, but not for the authoritarian filial type. The importance of the quality of the parent-child relationship and the internalization process related to children's assumptions of their parents' educational values indicate the need for a contextual view when examining predictors of student academic achievement.

Social Cognitive Antecedents of Fruit and Vegetable Consumption in Truck Drivers: A Sequential Mediation Analysis.

PubMed

Hamilton, Kyra; Vayro, Caitlin; Schwarzer, Ralf

2015-01-01

To examine a mechanism by which social cognitive factors may predict fruit and vegetable consumption in long-haul truck drivers. Dietary self-efficacy, positive outcome expectancies, and intentions were assessed in 148 Australian truck drivers, and 1 week later they reported their fruit and vegetable consumption. A theory-guided sequential mediation model was specified that postulated self-efficacy and intention as mediators between outcome expectancies and behavior. The hypothesized model was confirmed. A direct effect of outcome expectancies was no longer present when mediators were included, and all indirect effects were significant, including the 2-mediator chain (β = .15; P < .05; 95% confidence interval, 0.05-0.32). Truck drivers who expected benefits from dietary change, felt confident about being capable to do so, and formed an intention were likely to report larger amounts of fruit and vegetable intake. The results suggest that the role of outcome expectancies and self-efficacy are important to consider for understanding and predicting healthy eating intentions in truck drivers. Copyright © 2015 Society for Nutrition Education and Behavior. Published by Elsevier Inc. All rights reserved.

Anti-allergic activity of 2,4,6-trihydroxy-3-geranylacetophenone (tHGA) via attenuation of IgE-mediated mast cell activation and inhibition of passive systemic anaphylaxis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tan, Ji Wei; Israf, Daud Ahmad; Harith, Hanis Haze

tHGA, a geranyl acetophenone compound originally isolated from a local shrub called Melicope ptelefolia, has been previously reported to prevent ovalbumin-induced allergic airway inflammation in a murine model of allergic asthma by targeting cysteinyl leukotriene synthesis. Mast cells are immune effector cells involved in the pathogenesis of allergic diseases including asthma by releasing cysteinyl leukotrienes. The anti-asthmatic properties of tHGA could be attributed to its inhibitory effect on mast cell degranulation. As mast cell degranulation is an important event in allergic responses, this study aimed to investigate the anti-allergic effects of tHGA in cellular and animal models of IgE-mediated mastmore » cell degranulation. For in vitro model of IgE-mediated mast cell degranulation, DNP-IgE-sensitized RBL-2H3 cells were pre-treated with tHGA before challenged with DNP-BSA to induce degranulation. For IgE-mediated passive systemic anaphylaxis, Sprague Dawley rats were sensitized by intraperitoneal injection of DNP-IgE before challenged with DNP-BSA. Both in vitro and in vivo models showed that tHGA significantly inhibited the release of preformed mediators (β-hexosaminidase and histamine) as well as de novo mediators (interleukin-4, tumour necrosis factor-α, prostaglandin D{sub 2} and leukotriene C{sub 4}). Pre-treatment of tHGA also prevented IgE-challenged RBL-2H3 cells and peritoneal mast cells from undergoing morphological changes associated with mast cell degranulation. These findings indicate that tHGA possesses potent anti-allergic activity via attenuation of IgE-mediated mast cell degranulation and inhibition of IgE-mediated passive systemic anaphylaxis. Thus, tHGA may have the potential to be developed as a mast cell stabilizer for the treatment of allergic diseases in the future. - Highlights: • The in vitro and in vivo mast cell stabilizing effects of tHGA were examined. • tHGA counteracts the plasma membrane deformation in degranulating mast cells. • tHGA attenuates preformed and de novo mediators released by degranulating mast cells. • tHGA prevents in vivo mast cell activation and passive systemic anaphylaxis in rats. • tHGA could be a potential mast cell stabilizer for the treatment of allergic diseases.« less

iGWAS: Integrative Genome-Wide Association Studies of Genetic and Genomic Data for Disease Susceptibility Using Mediation Analysis.

PubMed

Huang, Yen-Tsung; Liang, Liming; Moffatt, Miriam F; Cookson, William O C M; Lin, Xihong

2015-07-01

Genome-wide association studies (GWAS) have been a standard practice in identifying single nucleotide polymorphisms (SNPs) for disease susceptibility. We propose a new approach, termed integrative GWAS (iGWAS) that exploits the information of gene expressions to investigate the mechanisms of the association of SNPs with a disease phenotype, and to incorporate the family-based design for genetic association studies. Specifically, the relations among SNPs, gene expression, and disease are modeled within the mediation analysis framework, which allows us to disentangle the genetic effect on a disease phenotype into two parts: an effect mediated through a gene expression (mediation effect, ME) and an effect through other biological mechanisms or environment-mediated mechanisms (alternative effect, AE). We develop omnibus tests for the ME and AE that are robust to underlying true disease models. Numerical studies show that the iGWAS approach is able to facilitate discovering genetic association mechanisms, and outperforms the SNP-only method for testing genetic associations. We conduct a family-based iGWAS of childhood asthma that integrates genetic and genomic data. The iGWAS approach identifies six novel susceptibility genes (MANEA, MRPL53, LYCAT, ST8SIA4, NDFIP1, and PTCH1) using the omnibus test with false discovery rate less than 1%, whereas no gene using SNP-only analyses survives with the same cut-off. The iGWAS analyses further characterize that genetic effects of these genes are mostly mediated through their gene expressions. In summary, the iGWAS approach provides a new analytic framework to investigate the mechanism of genetic etiology, and identifies novel susceptibility genes of childhood asthma that were biologically meaningful. © 2015 WILEY PERIODICALS, INC.

Angiogenin in Parkinson Disease Models: Role of Akt Phosphorylation and Evaluation of AAV-Mediated Angiogenin Expression in MPTP Treated Mice

PubMed Central

Steidinger, Trent U.; Slone, Sunny R.; Ding, Huiping; Standaert, David G.; Yacoubian, Talene A.

2013-01-01

The angiogenic factor, angiogenin, has been recently linked to both Amyotrophic Lateral Sclerosis (ALS) and Parkinson Disease (PD). We have recently shown that endogenous angiogenin levels are dramatically reduced in an alpha-synuclein mouse model of PD and that exogenous angiogenin protects against cell loss in neurotoxin-based cellular models of PD. Here, we extend our studies to examine whether activation of the prosurvival Akt pathway is required for angiogenin's neuroprotective effects against 1-methyl-4-phenylpyridinium (MPP+), as observed in ALS models, and to test the effect of virally-mediated overexpression of angiogenin in an in vivo PD model. Using a dominant negative Akt construct, we demonstrate that inhibition of the Akt pathway does not reduce the protective effect of angiogenin against MPP+ toxicity in the dopaminergic SH-SY5Y cell line. Furthermore, an ALS-associated mutant of angiogenin, K40I, which fails to induce Akt phosphorylation, was similar to wildtype angiogenin in protection against MPP+. These results confirm previous work showing neuroprotective effects of angiogenin against MPP+, and indicate that Akt is not required for this protective effect. We also investigated whether adeno-associated viral serotype 2 (AAV2)-mediated overexpression of angiogenin protects against dopaminergic neuron loss in the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) mouse model. We found that angiogenin overexpression using this approach does not reduce the MPTP-induced degeneration of dopaminergic cells in the substantia nigra, nor limit the depletion of dopamine and its metabolites in the striatum. Together, these findings extend the evidence for protective effects of angiogenin in vitro, but also suggest that further study of in vivo models is required to translate these effects into meaningful therapies. PMID:23409128

Teen Dating Violence, Sexual Harassment, and Bullying Among Middle School Students: Examining Mediation and Moderated Mediation by Gender.

PubMed

Cutbush, Stacey; Williams, Jason; Miller, Shari

2016-11-01

This longitudinal study tested whether sexual harassment perpetration mediates the relationship between bullying perpetration and teen dating violence (TDV) perpetration and tested moderated mediation by assessing whether the developmental pathway varies by gender among middle school-aged youth. Although TDV has been associated with bullying and sexual harassment, the developmental relationship among all three behaviors has rarely been examined, especially by gender. The data were collected from one cohort of seventh grade middle school students (N = 612) from four schools. Students were surveyed every 6 months during seventh and eighth grades for a total of four waves of data collection. Structural equation modeling (SEM) was conducted to address the study aims, consisting of three stages: measurement models, mediation, and moderated mediation (otherwise known as Contrast of Mediated Effects). Results indicate no evidence of mediation. However, in the overall model, bullying and sexual harassment both emerged as significant predictors of TDV at a later time point. Among girls, only bullying significantly predicted TDV at a later time point, and, among boys, only sexual harassment significantly predicted TDV at a later time point. Prevention programs that target bullying and sexual harassment perpetration may reduce later perpetration of TDV. Further research is needed to disentangle the temporal relationships between these aggressive behaviors among youth.

Effect of theory of mind and peer victimization on the schizotypy-aggression relationship.

PubMed

Lam, Bess Y H; Raine, Adrian; Lee, Tatia M C

2016-01-01

Prior longitudinal studies have established the relationship between schizophrenia and violence. However, previous studies on aggression and schizotypal personality are scarce. The present study examines whether peer victimization mediates the relationship between schizotypy and reactive-proactive aggression, and whether theory of mind (ToM) moderates this mediation. Schizotypy, peer victimization, reactive-proactive aggression, and ToM were assessed in 237 undergraduates. Peer victimization mediated the relationship between schizotypy and reactive aggression. ToM moderated this mediation effect; although peer victimization partially explains the schizotypy-aggression relationship, higher ToM skills weakened the detrimental effect of schizotypy on peer victimization which in turn reduces reactive aggression. In contrast, the moderated mediation was not significant for the proactive aggression model. Findings help delineate the underlying mechanism of the relationship between schizotypy and aggression. It is suggested that aggression could be reduced by enhancing ToM skills, thereby reducing peer victimization and the resultant schizotypy.

Effect of theory of mind and peer victimization on the schizotypy–aggression relationship

PubMed Central

Lam, Bess Y H; Raine, Adrian; Lee, Tatia M C

2016-01-01

Prior longitudinal studies have established the relationship between schizophrenia and violence. However, previous studies on aggression and schizotypal personality are scarce. The present study examines whether peer victimization mediates the relationship between schizotypy and reactive-proactive aggression, and whether theory of mind (ToM) moderates this mediation. Schizotypy, peer victimization, reactive-proactive aggression, and ToM were assessed in 237 undergraduates. Peer victimization mediated the relationship between schizotypy and reactive aggression. ToM moderated this mediation effect; although peer victimization partially explains the schizotypy–aggression relationship, higher ToM skills weakened the detrimental effect of schizotypy on peer victimization which in turn reduces reactive aggression. In contrast, the moderated mediation was not significant for the proactive aggression model. Findings help delineate the underlying mechanism of the relationship between schizotypy and aggression. It is suggested that aggression could be reduced by enhancing ToM skills, thereby reducing peer victimization and the resultant schizotypy. PMID:27336052

[Effects of nurses' mentoring on turnover intention: focused on the mediating effects role stress and burnout].

PubMed

Han, Sangsook; Kim, Ohsook; Joo, Yunsu; Choi, Eunduck; Han, Jeongwon

2013-10-01

The purpose of this study was to investigate the casual relationship between nurses' mentoring and turnover intention and to verify the goodness of fit between a hypothetical model and actual data in order to suggest an adequate model. The survey was conducted with 434 nurses working in general hospitals in Seoul. Data were collected during February 2013, and analyzed with SPSS Windows 18.0 and AMOS 7.0. Mentoring was found to have a direct effect on decrease in role stress. Role stress had a direct effect on increase in burnout and mentoring, with role stress as a mediator, there was an indirect effect on burnout. Burnout had a direct effect on increase in turnover intention, and role stress, with burnout as a mediator, and mentoring, through role stress and burnout, an indirect effect was found on increase in turnover intention. The results of this study indicate that nursing managers should put effort into reducing role stress and burnout, while seeking to establish a more efficient mentoring system so that for nurses, there will be a lowering of turnover intention.

The relationship of social support with treatment adherence and weight loss in Latinos with type 2 diabetes.

PubMed

Marquez, Becky; Anderson, Andrea; Wing, Rena R; West, Delia S; Newton, Robert L; Meacham, Maria; Hazuda, Helen P; Peters, Anne; Montez, Maria G; Broyles, Stephanie T; Walker, Martha; Evans-Hudsnall, Gina

2016-03-01

Little is known about the effects of social support on weight loss in Latinos. This study determined whether sex moderated and treatment adherence mediated the association between social support and weight loss. Data from 278 Latino males and females with type 2 diabetes in the Intensive Lifestyle Intervention of the Look AHEAD trial were analyzed. Multivariable modeling tested for moderation and parallel multiple mediator modeling simultaneously tested the mediating effects of adherence to physical activity, diet, and session attendance on the relationship between baseline social support and percent weight loss at 1 year. Social support for physical activity (having family and friends join in physical activity) was related to weight loss. Adherence to physical activity was related to both social support for physical activity and weight loss. Sex did not moderate these relationships. Adherence to physical activity completely mediated the relationship between social support for physical activity and weight loss. Increasing companionship for physical activity may be an effective intervention strategy to promote behaviors important for weight loss among Latinos. © 2016 The Obesity Society.

The relationship of social support with treatment adherence and weight loss in Latinos with type 2 diabetes

PubMed Central

Marquez, Becky; Anderson, Andrea; Wing, Rena R.; West, Delia S.; Newton, Robert L.; Meacham, Maria; Hazuda, Helen P.; Peters, Anne; Montez, Maria G.; Broyles, Stephanie T.; Walker, Martha; Evans-Hudsnall, Gina

2016-01-01

Objective Little is known about the effects of social support on weight loss in Latinos. This study determined whether sex moderated and treatment adherence mediated the association between social support and weight loss. Methods Data from 278 Latino males and females with type 2 diabetes in the Intensive Lifestyle Intervention of the Look AHEAD trial were analyzed. Multivariable modeling tested for moderation and parallel multiple mediator modeling simultaneously tested the mediating effects of adherence to physical activity, diet, and session attendance on the relationship between baseline social support and percent weight loss at 1 year. Results Social support for physical activity (having family and friends join in physical activity) was related to weight loss. Adherence to physical activity was related to both social support for physical activity and weight loss. Sex did not moderate these relationships. Adherence to physical activity completely mediated the relationship between social support for physical activity and weight loss. Conclusion Increasing companionship for physical activity may be an effective intervention strategy to promote behaviors important for weight loss among Latinos. PMID:26833676

Host-Specific Response to HCV Infection in the Chimeric SCID-beige/Alb-uPA Mouse Model: Role of the Innate Antiviral Immune Response

PubMed Central

Thompson, Jill C; Smith, Maria W; Yeh, Matthew M; Proll, Sean; Zhu, Lin-Fu; Gao, T. J; Kneteman, Norman M; Tyrrell, D. Lorne; Katze, Michael G

2006-01-01

The severe combined immunodeficiency disorder (SCID)-beige/albumin (Alb)-urokinase plasminogen activator (uPA) mouse containing a human-mouse chimeric liver is currently the only small animal model capable of supporting hepatitis C virus (HCV) infection. This model was utilized to characterize the host transcriptional response to HCV infection. The purpose of these studies was to investigate the genetic component of the host response to HCV infection and also to distinguish virus-induced gene expression changes from adaptive HCV-specific immune-mediated effects. Gene expression profiles from HCV-infected mice were also compared to those from HCV-infected patients. Analyses of the gene expression data demonstrate that host factors regulate the response to HCV infection, including the nature of the innate antiviral immune response. They also indicate that HCV mediates gene expression changes, including regulation of lipid metabolism genes, which have the potential to be directly cytopathic, indicating that liver pathology may not be exclusively mediated by HCV-specific adaptive immune responses. This effect appears to be inversely related to the activation of the innate antiviral immune response. In summary, the nature of the initial interferon response to HCV infection may determine the extent of viral-mediated effects on host gene expression. PMID:16789836

Stressful life events, ethnic identity, historical trauma, and participation in cultural activities: Associations with smoking behaviors among American Indian adolescents in California.

PubMed

Soto, Claradina; Baezconde-Garbanati, Lourdes; Schwartz, Seth J; Unger, Jennifer B

2015-11-01

American Indian (AI) adolescents have the highest prevalence of commercial tobacco use of any ethnic group in the United States. This study examines ethnic identity (EI), participation in cultural activities, and stressful life events (SLEs) as correlates of smoking and examines historical trauma (HT) as a mediator of these associations. California AI youth (N = 969, ages 13-19, recruited from 49 tribal youth organizations and cultural activities in urban and reservation areas in California) completed a tobacco survey. Structural equation modeling was used to test a model examining HT as a potential mediator of the associations of EI, participation in cultural activities, and SLEs with cigarette smoking. Model fit was adequate. EI, participation in cultural activities, and SLEs predicted HT. HT mediated the associations of participation in cultural activities and SLEs with past-month smoking. Stronger EI predicted greater past-month smoking and this effect was mediated by greater HT. The direct effects from HT to both smoking outcomes were positive and the direct effect from EI to past-month smoking was negative. HT is a risk factor for cigarette smoking both directly and in mediating the links of EI, cultural activities, and SLEs. More efforts are needed to help AI youth to process these thoughts and empower themselves to contribute to their own lives and those of their families and communities without resorting to unhealthy addictive behaviors such as commercial tobacco use. Published by Elsevier Ltd.

Stressful Life Events, Ethnic Identity, Historical Trauma, and Participation in Cultural Activities: Associations with Smoking Behaviors among American Indian Adolescents in California

PubMed Central

Soto, Claradina; Baezconde-Garbanati, Lourdes; Schwartz, Seth J.; Unger, Jennifer B.

2015-01-01

Introduction American Indian (AI) adolescents have the highest prevalence of commercial tobacco use of any ethnic group in the United States. This study examines ethnic identity (EI), participation in cultural activities, and stressful life events (SLEs) as correlates of smoking and examines historical trauma (HT) as a mediator of these associations. Methods California AI youth (N= 969, ages 13–19, recruited from 49 tribal youth organizations and cultural activities in urban and reservation areas in California) completed a tobacco survey. Structural equation modeling was used to test a model examining HT as a potential mediator of the associations of EI, participation in cultural activities, and SLEs with cigarette smoking. Results Model fit was adequate. EI, participation in cultural activities, and SLEs predicted HT. HT mediated the associations of participation in cultural activities and SLEs with past-month smoking. Stronger EI predicted greater past-month smoking and this effect was mediated by greater HT. The direct effects from HT to both smoking outcomes were positive and the direct effect from EI to past-month smoking was negative. Conclusions HT is a risk factor for cigarette smoking both directly and in mediating the links of EI, cultural activities, and SLEs. More efforts are needed to help AI youth to process these thoughts and empower themselves to contribute to their own lives and those of their families and communities without resorting to unhealthy addictive behaviors such as commercial tobacco use. PMID:26103424

The Multifaceted Role of Attachment during Preschool: Moderator of Its Indirect Effect on Empathy through Emotion Regulation

ERIC Educational Resources Information Center

Stefan, Catrinel A.; Avram, Julia

2018-01-01

The aims of the current study were (1) to replicate findings regarding the mediator role of emotion regulation (ER) between attachment and empathy; (2) to extend current knowledge by testing the moderator effect of ER on the relationship between attachment and empathy; and (3) to test an integrative moderated mediation model in which attachment…

Four Mediation Models of Teacher Expectancy Effects on Students' Outcomes in Mathematics and Literacy

ERIC Educational Resources Information Center

Trusz, Slawomir

2018-01-01

The study tested 4 direct and 28 indirect teacher expectancy effects on students' results in the mathematics and literacy sections of the matriculation test, and their final marks in the 12th-grade mathematics and literacy class. The following were considered as mediators: student self-esteem, their self-expectancy, and time spent learning…

The Measurement Structure, Stability and Mediating Effects of Achievement Goals in Math with Middle-School Student Data

ERIC Educational Resources Information Center

Chiang, Yu-Tzu; Lin, Sunny S. J.

2014-01-01

This study examined the measurement structure, cross-year stability of achievement goals, and mediating effects of achievement goals between self-efficacy and math grades in a national sample of Taiwan middle school students. The measurement model with factorial structure showed good fit to the data. In the panel data (N?=?343), four achievement…

The Mediating Role of Self-Esteem: The Effects of Social Support and Subjective Well-Being on Adolescents' Risky Behaviors

ERIC Educational Resources Information Center

Savi Çakar, Firdevs; Tagay, Özlem

2017-01-01

This research is a descriptive study based on the testing of a structural model developed by considering the effects of perceived social support and subjective well-being on adolescents' risky behaviors, and the possible mediating role of self-esteem. Participants consisted of 676 high school students attending formal education institutions,…

Organizational justice and health: Studying mental preoccupation with work and social support as mediators for lagged and reversed relationships.

PubMed

Eib, Constanze; Bernhard-Oettel, Claudia; Magnusson Hanson, Linda L; Leineweber, Constanze

2018-03-05

Organizational justice perceptions are considered a predictor of health and well-being. To date, empirical evidence about whether organizational justice perceptions predict health or health predicts organizational justice perceptions is mixed. Furthermore, the processes underlying these relationships are largely unknown. In this article, we study whether bidirectional relationships can be explained by 2 different mediation mechanisms. First, based on the allostatic load model, we suggest that the relationships between organizational justice perceptions and different health indicators are mediated through mental preoccupation with work. Second, based on the affective perception and affective reaction assumption, we investigate if the relationships between different health indicators and organizational justice perceptions are mediated by social support at work. Using a large-scale Swedish panel study (N = 3,236), we test the bidirectional mediating relationships between procedural justice perceptions and self-rated health, depressive symptoms, and sickness absence with a cross-lagged design with 3 waves of data. Significant lagged effects from procedural justice to health were found for models predicting depressive symptoms and sickness absence. Mental preoccupation with work was not found to mediate the longitudinal relationship between procedural justice perceptions and indicators of health. Significant lagged effects from health indicators to procedural justice were found for models involving self-rated health, depressive symptoms, and sickness absence. Social support mediated the longitudinal relationships between all 3 health indicators and procedural justice. Results are discussed in light of previous studies and implications for theory and practice are outlined. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

Overweight, Body Image, and Depression in Asian and Hispanic Adolescents

PubMed Central

Xie, Bin; Unger, Jennifer B.; Gallaher, Peggy; Johnson, C. Anderson; Wu, Qiaobing; Chou, Chih-Ping

2010-01-01

Objectives To prospectively investigate associations between overweight and depressive symptoms in Asian and Hispanic adolescents. Methods Data included 780 Hispanic and 375 Asian students. Structural equation model was used to prospectively explore moderation effects of gender, ethnicity, and acculturation on associations of overweight, body image dissatisfaction, and depressive symptoms. Results Significant mediation effect was found only in Asian girls (mediation effect=0.16, P<0.05) and girls with high acculturation (mediation effect=0.17, P<0.05). Overweight significantly predicted higher body image dissatisfaction, which in turn was significantly related to depressive symptoms. Conclusion Our findings help understanding the association of overweight and experience of depressive symptoms. PMID:20218759

Mediators of the Relation between Childhood Sexual Abuse and Women’s Sexual Risk Behavior: A Comparison of Two Theoretical Frameworks

PubMed Central

Senn, Theresa E.; Carey, Michael P.; Coury-Doniger, Patricia

2012-01-01

Childhood sexual abuse (CSA) is associated with sexual risk behavior in adulthood, but little research has investigated processes that might mediate this relation. The purpose of this study was to investigate whether constructs suggested by the traumagenic dynamics (TD) model (a theory of the effects of CSA) or constructs suggested by the Information-Motivation-Behavioral skills (IMB) model (a theory of the antecedents of sexual risk behavior) better mediated the relation between CSA and sexual risk behavior in adulthood. Participants were 481 women attending an STI clinic (66% African American) who completed a computerized survey as well as behavioral simulations assessing condom application and sexual assertiveness skills. Forty-five percent of the sample met criteria for CSA and CSA was associated with sexual risk behavior in adulthood. In multiple mediator models, the TD constructs mediated the relation between CSA and the number of sexual partners whereas the IMB constructs mediated the relation between CSA and unprotected sex. In addition, the TD constructs better mediated the relation between CSA and the number of sexual partners; the TD and IMB constructs did not differ in their ability to mediate the relation between CSA and unprotected sex. Sexual risk reduction interventions for women who were sexually abused should target not only the constructs from health behavior models (e.g., motivation and skills to reduce sexual risk), but also constructs that are specific to sexual abuse (e.g., traumatic sexualization and guilt). PMID:22282323

Do Personality Traits Mediate the Relationship Between Childhood Abuse and Migraine? An Exploration of the Relationships in Young Adults Using the Add Health Dataset.

PubMed

Karmakar, Monita; Elhai, Jon D; Amialchuk, Aliaksandr A; Tietjen, Gretchen E

2018-02-01

Personality traits (especially neuroticism) and childhood maltreatment have been independently related to many negative health outcomes later in life, including migraine. Studies have also shown the association between childhood maltreatment and maladaptive personality traits. The mediating role of personality traits on the relationship between childhood maltreatment and depression, psychological distress, and alcohol dependence has been extensively studied. However, this type of mediation has not been studied in the case of the development of migraine. This study investigated (1) the main effects of childhood abuse on personality traits, and of personality traits on migraine, and (2) the mediating role of neuroticism, on the relationship between childhood abuse and migraine in young adults. We analyzed retrospective, cross-sectional data from 13,493 adults aged 24-32 years in Wave 4 of the National Longitudinal Survey of Adolescent Health ("Add Health") data set. Participants were queried regarding maltreatment (emotional, physical, and sexual) during childhood, current Big Five personality traits (using mini International Personality Item Pool), current depression (using Center for Epidemiologic Studies-Depression Scale), perceived stress (Using Cohen's Perceived Stress Scale), and diagnosis of migraine by a health care provider. Linear and logistic regressions were used to assess the main effects of childhood maltreatment on the five personality traits (openness to experience, conscientiousness, extraversion, agreeableness, and neuroticism) and the main effect of the personality traits on self-reported provider diagnosis of migraine. A structural equation model (SEM) was used to examine the mediating role of neuroticism on the relationship between childhood maltreatment and migraine. Linear regression models showed that childhood abuse independently predicted increased neuroticism (β = 0.338, SE=±0.05, P < .001), and increased openness to experiences (β = 0.341, SE = ±0.06, P < .001) after adjusting for socio-demographic characteristics, current depression, and perceived stress. Logistic regression to examine the main effect of personality traits on migraine revealed that only neuroticism had a significant effect (OR = 1.07, 95%CI = 1.04-1.10) after controlling for childhood abuse, socio-demographic characteristics, current depression, and perceived stress. Our regression analyses showed that neuroticism, but not openness to experience, was a potential mediator for the relationship between childhood abuse and migraine. SEM confirmed significant mediation of the relationship between childhood abuse and migraine through neurotic personality traits (goodness of fit indices: CFI = 0.992, TLI = 0.979, RMSEA = 0.025), unadjusted for socio-demographic variables, depression, and stress. In addition to the indirect effect (β = 0.039, P < .01) of childhood abuse on migraine through neuroticism, there was also a significant direct effect (β = 0.143, P < .01) of childhood abuse on migraine. After adjusting for socio-demographic variables, other personality types, depression, and stress, both the direct effect (β = 0.127; P < .01) of childhood abuse on migraine and the indirect effect (β = 0.09; P < .01) of childhood abuse on migraine through neuroticism were attenuated, but remained significant. Childhood abuse is associated with personality and migraine. An estimated 21% of the total effect of childhood abuse on migraine could be explained by mediation through neuroticism in the unadjusted model. In the fully adjusted model, an estimated 8.7% of the total effect could be explained by mediation, although, self-reported data limit the ability to draw firm conclusions. © 2017 American Headache Society.

Rumination and depression in Chinese university students: The mediating role of overgeneral autobiographical memory.

PubMed

Kong, Tianzhu; He, Yini; Auerbach, Randy P; McWhinnie, Chad M; Xiao, Jing

2015-04-01

In this study, we examined the mediator effects of overgeneral autobiographical memory (OGM) on the relationship between rumination and depression in 323 Chinese university students. 323 undergraduates completed the questionnaires measuring OGM (Autobiographical Memory Test), rumination (Ruminative Response Scale) and depression (Center for Epidemiologic Studies Depression Scale). Results using structural equation modeling showed that OGM partially-mediated the relationship between rumination and depression (χ 2 = 88.61, p < .01; RMSEA = .051; SRMR = .040; and CFI = .91). Bootstrap methods were used to assess the magnitude of the indirect effects. The results of the bootstrap estimation procedure and subsequent analyses indicated that the indirect effects of OGM on the relationship between rumination and depressive symptoms were significant. The results indicated that rumination and depression were partially mediated by OGM.

How Is the Effect of Adolescent E-cigarette Use on Smoking Onset Mediated: A Longitudinal Analysis

PubMed Central

Wills, Thomas A.; Gibbons, Frederick X.; Sargent, James D.; Schweitzer, Rebecca J.

2016-01-01

E-cigarette use by adolescents has been related to onset of cigarette smoking but there is little knowledge about the process(es) through which this occurs. Accordingly, we tested the role of cognitive and social factors for mediating the relation between e-cigarette use and smoking onset. A school-based survey was conducted with a baseline sample of 2,338 students in Hawaii (9th and 10th graders, mean age 14.7 years) who were surveyed in 2013 (Time 1, T1) and followed up 1 year later (Time 2, T2). We assessed e-cigarette use, cigarette smoking, demographic covariates, and four hypothesized mediators: smoking-related expectancies, prototypes, and peer affiliations as well as marijuana use. The primary structural modeling analysis, based on initial never-smokers, used an autoregressive model (entering T2 mediator values adjusted for T1 values) to test for mediational pathways in the relation between e-cigarette use at T1 and cigarette smoking status at T2. Results showed that e-cigarette use was related to all of the mediators and tests of indirect effects indicated that changes in expectancies, affiliations, and marijuana use were significant pathways in the relation between e-cigarette use and smoking onset. A direct effect from e-cigarette use to smoking onset was nonsignificant. Findings were replicated across autoregressive and prospective models. We conclude that the relation between adolescent e-cigarette use and smoking onset is in part attributable to cognitive and social processes that follow from e-cigarette use. Further research is needed to understand the relative role of nicotine and psychosocial factors in smoking onset. PMID:27669093

How is the effect of adolescent e-cigarette use on smoking onset mediated: A longitudinal analysis.

PubMed

Wills, Thomas A; Gibbons, Frederick X; Sargent, James D; Schweitzer, Rebecca J

2016-12-01

E-cigarette use by adolescents has been related to onset of cigarette smoking but there is little knowledge about the process(es) through which this occurs. Accordingly, we tested the role of cognitive and social factors for mediating the relation between e-cigarette use and smoking onset. A school-based survey was conducted with a baseline sample of 2,338 students in Hawaii (9th and 10th graders, mean age 14.7 years) who were surveyed in 2013 (Time 1, T1) and followed up 1 year later (Time 2, T2). We assessed e-cigarette use, cigarette smoking, demographic covariates, and 4 hypothesized mediators: smoking-related expectancies, prototypes, and peer affiliations as well as marijuana use. The primary structural modeling analysis, based on initial never-smokers, used an autoregressive model (entering T2 mediator values adjusted for T1 values) to test for mediational pathways in the relation between e-cigarette use at T1 and cigarette smoking status at T2. Results showed that e-cigarette use was related to all of the mediators. Tests of indirect effects indicated that changes in expectancies, affiliations, and marijuana use were significant pathways in the relation between e-cigarette use and smoking onset. A direct effect from e-cigarette use to smoking onset was nonsignificant. Findings were replicated across autoregressive and prospective models. We conclude that the relation between adolescent e-cigarette use and smoking onset is in part attributable to cognitive and social processes that follow from e-cigarette use. Further research is needed to understand the relative role of nicotine and psychosocial factors in smoking onset. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

Mediator and moderator effects in developmental and behavioral pediatric research.

PubMed

Rose, Brigid M; Holmbeck, Grayson N; Coakley, Rachael Millstein; Franks, Elizabeth A

2004-02-01

The terms mediation and moderation are defined and clarified with particular emphasis on the role of mediational and moderational analyses in developmental and behavioral pediatric research. The article highlights the applicability of mediational and moderational analyses to longitudinal, intervention, and risk and protective factor research, and it provides basic information about how these analyses might be conducted. Also included is a discussion of various ways that both mediator and moderator variables can be incorporated into a single model. The article concludes with extended examples of both types of analyses using a longitudinal pediatric study for illustration. The article provides recommendations for applying mediational and moderational research in clinical practice.

Hazardous drinking and military community functioning: identifying mediating risk factors.

PubMed

Foran, Heather M; Heyman, Richard E; Slep, Amy M Smith

2011-08-01

Hazardous drinking is a serious societal concern in military populations. Efforts to reduce hazardous drinking among military personnel have been limited in effectiveness. There is a need for a deeper understanding of how community-based prevention models apply to hazardous drinking in the military. Community-wide prevention efforts may be most effective in targeting community functioning (e.g., support from formal agencies, community cohesion) that impacts hazardous drinking via other proximal risk factors. The goal of the current study is to inform community-wide prevention efforts by testing a model of community functioning and mediating risk factors of hazardous drinking among active duty U.S. Air Force personnel. A large, representative survey sample of U.S. Air Force active duty members (N = 52,780) was collected at 82 bases worldwide. Hazardous drinking was assessed with the widely used Alcohol Use Disorders Identification Test (Saunders, Aasland, Babor, de la Fuente, & Grant, 1993). A variety of individual, family, and community measures were also assessed. Structural equation modeling was used to test a hypothesized model of community functioning, mediating risk factors and hazardous drinking. Depressive symptoms, perceived financial stress, and satisfaction with the U.S. Air Force were identified as significant mediators of the link between community functioning and hazardous drinking for men and women. Relationship satisfaction was also identified as a mediator for men. These results provide a framework for further community prevention research and suggest that prevention efforts geared at increasing aspects of community functioning (e.g., the U.S. Air Force Community Capacity model) may indirectly lead to reductions in hazardous drinking through other proximal risk factors.

Antiapoptotic and Trophic Effects of Dominant-Negative Forms of Dual Leucine Zipper Kinase in Dopamine Neurons of the Substantia Nigra In Vivo

PubMed Central

Chen, Xiqun; Rzhetskaya, Margarita; Kareva, Tatyana; Bland, Ross; During, Matthew J.; Tank, A. William; Kholodilov, Nikolai; Burke, Robert E.

2009-01-01

There is extensive evidence that the mitogen-activated protein kinase (MAPK) signaling cascade mediates programmed cell death in neurons. However, current evidence that the mixed linage kinases (MLKs), upstream in this cascade, mediate cell death is based, in the in vivo context, entirely on pharmacological approaches. The compounds used in these studies have neither complete specificity nor selectivity among these kinases. Therefore, to better address the molecular specificity of the MLKs in mediating neuron death, we used dominant-negative constructs delivered by AAV (adenoassociated virus) vector transfer. We assessed effects in a neurotoxin model of parkinsonism, in which neuroprotection by pharmacologic MLK inhibition has been reported. We find that two dominant-negative forms of dual leucine zipper kinase (DLK) inhibit apoptosis and enhance long-term survival of dopamine neurons, but a dominant negative of MLK3 does not. Interestingly, the kinase-dead form of DLK not only blocks apoptosis but also has trophic effects on dopamine neurons. Although the MAPK cascade activates a number of downstream cell death mediators, we find that inhibition of DLK correlates closely with blockade of phosphorylation of c-jun and prevention of cell death. We conclude that DLK acts primarily through c-jun phosphorylation to mediate cell death in this model. PMID:18199767

Finding benefits from acculturative stress among Asian Americans: Self-reflection moderating the mediating effects of ethnocultural empathy on positive outcomes.

PubMed

Wei, Meifen; Li, Chun-I; Wang, Cixin; Ko, Stacy Y

2016-11-01

This study examined a moderated mediation model to see whether self-reflection moderated (a) the association between acculturative stress and ethnocultural empathy and (b) the indirect effects of acculturative stress on 2 positive outcomes (i.e., bicultural competence and making positive sense of adversity) through ethnocultural empathy. A total of 330 Asian American college students from a West coast university participated in an online survey. Results from PROCESS supported hypotheses. First, self-reflection significantly moderated the effects of acculturative stress on ethnocultural empathy. Specifically, the effect of acculturative stress on ethnocultural empathy was significantly positive for those with lower self-reflection. Conversely, this effect was not significant for those with higher self-reflection, but ethnocultural empathy was consistently high across all levels of acculturative stress for those with higher self-reflection. Post hoc exploratory analyses examined the moderated mediation model using each of the 5 domains of acculturative stress as predictors; results supported the moderated mediation hypotheses for 2 domains, discrimination and cultural isolation. Second, self-reflection significantly moderated the indirect effects of acculturative stress on 2 positive outcomes through ethnocultural empathy. Results from conditional indirect effects suggested that the indirect effects of acculturative stress on 2 positive outcomes through ethnocultural empathy were significantly positive for those with lower self-reflection. Conversely, the indirect effects were not significant for those with higher self-reflection, but the 2 positive outcomes stayed high at all levels of acculturative stress. Post hoc analyses found that 5 of 6 components of bicultural competence used as outcome variables supported the moderation mediation hypotheses. (PsycINFO Database Record (c) 2016 APA, all rights reserved).

Magnitude and Mechanism of Siderophore-Mediated Competition at Low Iron Solubility in the Pseudomonas aeruginosa Pyochelin System.

PubMed

Schiessl, Konstanze T; Janssen, Elisabeth M-L; Kraemer, Stephan M; McNeill, Kristopher; Ackermann, Martin

2017-01-01

A central question in microbial ecology is whether microbial interactions are predominantly cooperative or competitive. The secretion of siderophores, microbial iron chelators, is a model system for cooperative interactions. However, siderophores have also been shown to mediate competition by sequestering available iron and making it unavailable to competitors. The details of how siderophores mediate competition are not well understood, especially considering the complex distribution of iron phases in the environment. One pertinent question is whether sequestering iron through siderophores can indeed be effective in natural conditions; many natural environments are characterized by large pools of precipitated iron, and it is conceivable that any soluble iron that is sequestered by siderophores is replenished by the dissolution of these precipitated iron sources. Our goal here was to address this issue, and investigate the magnitude and mechanism of siderophore-mediated competition in the presence of precipitated iron. We combined experimental work with thermodynamic modeling, using Pseudomonas aeruginosa as a model system and ferrihydrite precipitates as the iron source with low solubility. Our experiments show that competitive growth inhibition by the siderophore pyochelin is indeed efficient, and that inhibition of a competitor can even have a stronger growth-promoting effect than solubilization of precipitated iron. Based on the results of our thermodynamic models we conclude that the observed inhibition of a competitor is effective because sequestered iron is only very slowly replenished by the dissolution of precipitated iron. Our research highlights the importance of competitive benefits mediated by siderophores, and underlines that the dynamics of siderophore production and uptake in environmental communities could be a signature of competitive, not just cooperative, dynamics.

Recent advances in behavioral addiction treatments: focusing on mechanisms of change.

PubMed

Longabaugh, Richard; Magill, Molly

2011-10-01

In the latter half of the 20th century, research on behavioral treatments for addictions aimed to develop and test effective treatments. Among the treatments found to be at least moderately effective, direct comparisons failed to reveal consistent superiority of one approach over another. This ubiquitous finding held true despite underlying theories that differed markedly in their proposed causal processes related to patient change. In the 21st century, the focus of treatment research is increasingly on how treatment works for whom rather than whether it works. Studies of active treatment ingredients and mechanisms of behavioral change, while promising, have yielded inconsistent results. Simple mediation analysis may need to be expanded via inclusion of models testing for moderated mediation, mediated moderation, and conditional indirect effects. Examples are offered as to how these more complex models can lead to increased understanding of the conditions under which specific treatment interventions will be effective and mechanisms of change operative in improving behavioral treatments for addictions.

Recent Advances in Behavioral Addiction Treatments: Focusing on Mechanisms of Change

PubMed Central

Longabaugh, Richard; Magill, Molly

2012-01-01

In the latter half of the 20th century, research on behavioral treatments for addictions aimed to develop and test effective treatments. Among treatments found to be at least moderately effective, direct comparisons failed to reveal consistent superiority of one approach over another. This ubiquitous finding held true despite underlying theories that differed markedly in their proposed causal processes related to patient change. In the 21st century the focus of treatment research is increasingly on how treatment works for whom, rather than whether it works. Studies of active treatment ingredients and mechanisms of behavioral change, while promising, have yielded inconsistent results. Simple mediation analysis may need to be expanded by inclusion of models testing for moderated mediation, mediated moderation, and conditional indirect effects. Examples are offered as to how these more complex models can lead to increased understanding of the conditions under which specific treatment interventions will be effective and mechanisms of change operative in improving behavioral treatments for addictions. PMID:21750958

Positive Emotional Effects of Leisure in Green Spaces in Alleviating Work–Family Spillover in Working Mothers

PubMed Central

Chang, Po-Ju; Bae, So Young

2017-01-01

Studies have shown that family and work spillover affects well-being and that leisure activities can alleviate the negative effects of work-related stress on health. However, few studies have focused on investigating the effects of specific leisure activities among specific populations. To examine whether leisure activities in green spaces can promote individual recovery processes and alleviate the effects of work and family spillover on positive emotions, this study applied the effort-recovery model to a population of working mothers. Through online and paper questionnaires, sample data were collected from 221 working mothers in Taiwan. Structural equation modeling was used to test the experimental hypothesis, and mediation analysis was used to determine whether leisure in green spaces is a mediating factor. The results indicated that leisure in green spaces is a mediator of the relationship of negative work and family spillover with positive emotions. In addition, strolls and park visits were found to provide greater psychological benefits to working mothers, compared with picnics. PMID:28696388

Positive Emotional Effects of Leisure in Green Spaces in Alleviating Work-Family Spillover in Working Mothers.

PubMed

Chang, Po-Ju; Bae, So Young

2017-07-11

Studies have shown that family and work spillover affects well-being and that leisure activities can alleviate the negative effects of work-related stress on health. However, few studies have focused on investigating the effects of specific leisure activities among specific populations. To examine whether leisure activities in green spaces can promote individual recovery processes and alleviate the effects of work and family spillover on positive emotions, this study applied the effort-recovery model to a population of working mothers. Through online and paper questionnaires, sample data were collected from 221 working mothers in Taiwan. Structural equation modeling was used to test the experimental hypothesis, and mediation analysis was used to determine whether leisure in green spaces is a mediating factor. The results indicated that leisure in green spaces is a mediator of the relationship of negative work and family spillover with positive emotions. In addition, strolls and park visits were found to provide greater psychological benefits to working mothers, compared with picnics.

Effects of organizational justice on organizational citizenship behaviors: mediating effects of institutional trust and affective commitment.

PubMed

Guh, Wei-Yuan; Lin, Shang-Ping; Fan, Chwei-Jen; Yang, Chin-Fang

2013-06-01

This study investigated the mediating role of institutional trust and affective commitment on the relationship between organizational justice and organizational citizenship behaviors. The study participants were 315 faculty members at 67 public/private universities of technology and vocational colleges in Taiwan. Structural equation modeling was used to analyze the relationships between the variables and assess the goodness of fit of the overall model. Organizational justice was positively related to institutional trust and there was an indirect effect of organizational justice on affective commitment through institutional trust. In addition, the relation between institutional trust and affective commitment was positive and affective commitment was shown to have a positive relation to organizational citizenship behaviors. Institutional trust was found to indirectly affect organizational citizenship behaviors through affective commitment. Most importantly, this study suggested a mediating effect of institutional trust and affective commitment on the relation between organizational justice and organizational citizenship behaviors. Implications, limitations, and future research were also discussed.

Pathway Linking Internet Health Information Seeking to Better Health: A Moderated Mediation Study.

PubMed

Jiang, Shaohai; Street, Richard L

2017-08-01

The Internet increasingly has been recognized as an important medium with respect to population health. However, little is known about the mechanisms that underlie the potential impact of health-related Internet use on health outcomes. Based on the three-stage model of health promotion using interactive media, this study empirically tested a moderated mediation pathway model. Results showed that the effect of Internet health information seeking on three health outcomes (general, emotional, and physical) was completely mediated by respondents' access to social support resources. In addition, users' online health information seeking experience positively moderated this mediation path. The findings have significant theoretical and practical implications for the design of Internet-based health promotion resources to improve health outcomes.

Self-control depletion and nicotine deprivation as precipitants of smoking cessation failure: A human laboratory model.

PubMed

Heckman, Bryan W; MacQueen, David A; Marquinez, Nicole S; MacKillop, James; Bickel, Warren K; Brandon, Thomas H

2017-04-01

The need to understand potential precipitants of smoking relapse is exemplified by relapse rates as high as 95%. The Self-Control Strength model, which proposes that self-control is dependent upon limited resources and susceptible to fatigue, may offer insight into relapse processes. The current study tested the hypothesis that self-control depletion (SCD), produced from engagement in emotional suppression, would serve as a novel antecedent for cessation failure, as indexed by a validated laboratory analogue of smoking lapse and relapse. We also examined whether SCD effects interacted with those of a well-established relapse precipitant (i.e., nicotine deprivation). Craving and behavioral economic indices (delay discounting and demand) were tested as hypothesized mechanisms for increased cessation failure. Ultimately, a moderated mediation model was used to test nicotine deprivation as a hypothesized moderator of SCD effects. We used a 2 × 2 (12-hr deprivation vs. no deprivation; SCD vs. no SCD) factorial between-subjects design (N = 128 smokers). The primary hypothesis of the study was supported, as SCD increased lapse behavior (p = .04). Nicotine deprivation significantly increased craving, cigarette demand, delay discounting, and lapse behavior. No main effects were found for SCD on putative mediators (i.e., craving, demand, and discounting), but the SCD and deprivation manipulations interacted upon craving (p = .04). The moderated mediation model was significant. SCD was found to increase craving among nicotine deprived smokers, which mediated effects on lapse behavior. SCD appears to play an important role in smoking relapse and may be a viable target for intervention. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

Self-Control Depletion and Nicotine Deprivation as Precipitants of Smoking Cessation Failure: A Human Laboratory Model

PubMed Central

Heckman, Bryan W.; MacQueen, David A.; Marquinez, Nicole S.; MacKillop, James; Bickel, Warren K.; Brandon, Thomas H.

2017-01-01

Objective The need to understand potential precipitants of smoking relapse is exemplified by relapse rates as high as 95%. The Self-Control Strength model, which proposes that self-control is dependent upon limited resources and susceptible to fatigue, may offer insight into relapse processes. The current study tested the hypothesis that self-control depletion (SCD), produced from engagement in emotional suppression, would serve as a novel antecedent for cessation failure, as indexed by a validated laboratory analogue of smoking lapse and relapse. We also examined whether SCD effects interacted with those of a well-established relapse precipitant (i.e., nicotine deprivation). Craving and behavioral economic indices (delay discounting and demand) were tested as hypothesized mechanisms for increased cessation failure. Ultimately, a moderated mediation model was used to test nicotine deprivation as a hypothesized moderator of SCD effects. Method We used a 2 ×2 (12-hour deprivation vs. no deprivation; SCD vs. no SCD) factorial between-subjects design (N = 128 smokers). Results The primary hypothesis of the study was supported, as SCD increased lapse behavior (p = .04). Nicotine deprivation significantly increased craving, cigarette demand, delay discounting, and lapse behavior. No main effects were found for SCD on putative mediators (i.e., craving, demand, discounting), but the SCD and deprivation manipulations interacted upon craving (p = .04). The moderated mediation model was significant. SCD was found to increase craving among nicotine deprived smokers, which mediated effects on lapse behavior. Conclusions SCD appears to play an important role in smoking relapse and may be a viable target for intervention. PMID:28333537

What are the combined effects of negative emotions and illness cognitions on self-care in people with type 2 diabetes? A longitudinal structural equation model.

PubMed

Hudson, Joanna L; Bundy, Christine; Coventry, Peter; Dickens, Chris; Wood, Alex; Reeves, David

2016-07-01

To explore whether negative emotions mediate the effect of diabetes cognitions on diabetes self-care and conversely whether diabetes cognitions mediate the effect of negative emotions on diabetes self-care. Longitudinal observational study in adults with type 2 diabetes. Self-reported depression and anxiety (Diabetes Wellbeing Questionnaire), cognitions (Illness Perceptions Questionnaire-Revised; Beliefs about Medicines Questionnaire), and diabetes self-care (Summary of Diabetes Self-Care Activities Scale) were completed at baseline and six months. Analyses used structural equation modelling. Baseline medication concerns were associated with elevated symptoms of depression and anxiety at follow-up, but emotions did not mediate medication concern's effect on diabetes self-care. Baseline depression and anxiety symptoms were associated with specific diabetes cognitions over time, but these cognition domains did not mediate emotion's effect on diabetes self-care. Personal control remained independent of emotions and was associated with diabetes self-care over time. Negative emotions did not act directly or alongside cognitions to influence diabetes self-care. The reciprocal relationship between diabetes cognitions and emotions suggests cognitive restructuring, in addition to other mood management intervention techniques would likely improve the emotional wellbeing of adults with type 2 diabetes. Likewise, personal control beliefs are likely important intervention targets for improving self-care.

Dengue Virus Infection Differentially Regulates Endothelial Barrier Function over Time through Type I Interferon Effects

PubMed Central

Liu, Ping; Woda, Marcia; Ennis, Francis A.; Libraty, Daniel H.

2013-01-01

Background The morbidity and mortality resulting from dengue hemorrhagic fever (DHF) are largely caused by endothelial barrier dysfunction and a unique vascular leakage syndrome. The mechanisms that lead to the location and timing of vascular leakage in DHF are poorly understood. We hypothesized that direct viral effects on endothelial responsiveness to inflammatory and angiogenesis mediators can explain the DHF vascular leakage syndrome. Methods We used an in vitro model of human endothelium to study the combined effects of dengue virus (DENV) type 2 (DENV2) infection and inflammatory mediators on paracellular macromolecule permeability over time. Results Over the initial 72 h after infection, DENV2 suppressed tumor necrosis factor (TNF)–α–mediated hyperpermeability in human umbilical vein endothelial cell (HUVEC) monolayers. This suppressive effect was mediated by type I interferon (IFN). By 1 week, TNF-α stimulation of DENV2-infected HUVECs synergistically increased cell cycling, angiogenic changes, and macromolecule permeability. This late effect could be prevented by the addition of exogenous type I IFN. Conclusions DENV infection of primary human endothelial cells differentially modulates TNF-α–driven angiogenesis and hyperpermeability over time. Type I IFN plays a central role in this process. Our findings suggest a rational model for the DHF vascular leakage syndrome. PMID:19530939

Materialism and addictive buying in women: the mediating role of anxiety and depression.

PubMed

Otero-López, José Manuel; Villardefrancos, Estíbaliz

2013-08-01

There is empirical evidence regarding the interrelationships between materialism, negative emotions, and addictive buying. The aim of this study was to clarify the direction of the relationships among these variables. Specifically, the main objective was to explore the possible mediating roles of anxiety and depression in the link between materialism and addictive buying. Path analysis results, using a sample of 685 women, generally supported the suitability of the proposed model in which anxiety and depression mediated the effects of the materialism dimensions, "importance" and "success," on addictive buying, and that depression also mediates the influence of the "importance" and "happiness" dimensions. Moreover, a direct effect of the importance dimension on addictive buying was found.

The mediating role of self-efficacy in the development of entrepreneurial intentions.

PubMed

Zhao, Hao; Seibert, Scott E; Hills, Gerald E

2005-11-01

The purpose of this study was to investigate the mediating role of self-efficacy in the development of students' intentions to become entrepreneurs. The authors used structural equation modeling with a sample of 265 master of business administration students across 5 universities to test their hypotheses. The results showed that the effects of perceived learning from entrepreneurship-related courses, previous entrepreneurial experience, and risk propensity on entrepreneurial intentions were fully mediated by entrepreneurial self-efficacy. Contrary to expectations, gender was not mediated by self-efficacy but had a direct effect such that women reported lower entrepreneurial career intentions. The authors discuss practical implications and directions for future research. ((c) 2005 APA, all rights reserved).

Tyrosine kinases activate store-mediated Ca2+ entry in human platelets through the reorganization of the actin cytoskeleton.

PubMed Central

Rosado, J A; Graves, D; Sage, S O

2000-01-01

We have recently reported that store-mediated Ca(2+) entry in platelets is likely to be mediated by a reversible trafficking and coupling of the endoplasmic reticulum with the plasma membrane, a model termed 'secretion-like coupling'. In this model the actin cytoskeleton plays a key regulatory role. Since tyrosine kinases have been shown to be important for Ca(2+) entry in platelets and other cells, we have now investigated the possible involvement of tyrosine kinases in the secretion-like-coupling model. Treatment of platelets with thrombin or thapsigargin induced actin polymerization by a calcium-independent pathway. Methyl 2,5-dihydroxycinnamate, a tyrosine kinase inhibitor, prevented thrombin- or thapsigargin-induced actin polymerization. The effects of tyrosine kinases in store-mediated Ca(2+) entry were found to be entirely dependent on the actin cytoskeleton. PP1, an inhibitor of the Src family of proteins, partially inhibited store-mediated Ca(2+) entry. In addition, depletion of intracellular Ca(2+) stores stimulated cytoskeletal association of the cytoplasmic tyrosine kinase pp60(src), a process that was sensitive to treatment with cytochalasin D and PP1, but not to inhibition of Ras proteins using prenylcysteine analogues. Finally, combined inhibition of both Ras proteins and tyrosine kinases resulted in complete inhibition of Ca(2+) entry, suggesting that these two families of proteins have independent effects in the activation of store-mediated Ca(2+) entry in human platelets. PMID:11023829

Nootropic activity of tuber extract of Pueraria tuberosa (Roxb).

PubMed

Rao, N Venkata; Pujar, Basavaraj; Nimbal, S K; Shantakumar, S M; Satyanarayana, S

2008-08-01

Nootropic effect of alcoholic (ALE; 50, 75, 100 mg/kg) and aqueous (AQE; 100, 200, 400 mg/kg) extracts of P. tuberosa was evaluated by using Elevated Plus Maze (EPM), scopolamine-induced amnesia (SIA), diazepam-induced amnesia (DIA), clonidine-induced (NA-mediated) hypothermia (CIH), lithium-induced (5-HT mediated) head twitches (LIH) and haloperidol-induced (DA- mediated) catalepsy (HIC) models. Piracetam was used as the standard drug. A significant increase in inflexion ratio (IR) was recorded in EPM, SIA and DIA models. A significant reversal effect was observed on rectal temperature in CIH model, reduction of head twitches in LIH models. However no significant reduction in catalepsy scores in HIC models were observed with test extracts and standard piracetam. The results indicate that nootropic activity observed with ALE and AQE of tuber extracts of P. tuberosa could be through improved learning and memory either by augmenting the noradrenaline (NA) transmission or by interfering with 5-hydroxytryptamine (5-HT) release. Further, the extracts neither facilitated nor blocked release of the dopamine (DA). Thus ALE and AQE elicited significant nootropic effect in mice and rats by interacting with cholinergic, GABAnergic, adrenergic and serotonergic systems. Phytoconstituents like flavonoids have been reported for their nootropic effect and these are present in both ALE and AQE extracts of tubers of P. tuberosa (Roxb) and these active principles may be responsible for nootropic activity.

Collective-efficacy as a mediator of the relationship of leaders' personality traits and team performance: A cross-level analysis.

PubMed

Li, Xiaoshan; Zhou, Mingjie; Zhao, Na; Zhang, Shanshan; Zhang, Jianxin

2015-06-01

The relationship between a leader's personality and his team's performance has been established in organisational research, but the underlying process and mechanism responsible for this effect have not been fully explored. Both the traditional multiple linear regression and the multilevel structural equation model approaches were used in this study to test a proposed mediating model of subordinates' perception of collective efficacy between leader personality and team performance. The results show that the team leader's extraversion and conscientiousness personality traits were related positively to both the team-average (individual) perception of collective efficacy and team performance, and the collective efficacy mediated the relationship of the leader's personality traits and team performance. This study also discusses how Chinese cultural elements play a role in such a mediating model. © 2014 International Union of Psychological Science.

Does Depressive Affect Mediate the Relationship between Self-Care Capacity and Nutritional Status Among Rural Older Adults? : A Structural Equation Modeling Approach.

PubMed

Jung, Seung Eun; Bishop, Alex J; Kim, Minjung; Hermann, Janice; Kim, Giyeon; Lawrence, Jeannine

2017-01-01

This study examined the relationships of self-care capacity and depressive affect on nutritional status and whether depressive affect mediated the relationship of self-care capacity on nutritional status. A convenience sample of 171 rural community-dwelling older adults, 65 years and above, participated. Structural equation modeling (SEM) was conducted to test a mediation model. The hypothesized SEM model was supported with adequate fit (χ 2 (1) = 1.87, p = 0.17; CFI = 0.94; RMSEA = 0.07; SRMR = 0.03). SEM analysis revealed a significant positive direct effect of self-care capacity on nutritional status (γ = 0.14, p = 0.042). Significant negative direct effects were observed for self-care capacity on depressive affect (γ = -0.15, p = 0.027) and for depressive affect on nutritional status (β = -0.27, p < 0.01). Depressive affect was also observed to partially mediate the relationship of self-care capacity on nutrition status (γ = 0.04, p = 0.046). Findings highlight the importance of emotional well-being on rural older adults' nutritional status, particularly those with decreased ability to engage in self-care practices.

Attachment insecurity as a mediator of the relationship between childhood trauma and adult dissociation.

PubMed

Kong, Seong Sook; Kang, Dae Ryong; Oh, Min Jung; Kim, Nam Hee

2018-01-01

This study aimed to investigate whether attachment insecurity mediates the relationship between childhood trauma and adult dissociation, specifically with regard to individual forms of childhood maltreatment. Psychiatric outpatients who visited a specialized trauma clinic (n = 115) participated in the study. Data were collected via the Childhood Trauma Questionnaire, Revised Adult Attachment Scale, and Dissociative Experience Scale. Structural equation modeling and path analysis were performed to analyze the mediating effects of attachment insecurity on the relationship between childhood trauma and adult dissociation. Greater childhood trauma was associated with higher dissociation, and the relationship between them was fully mediated by attachment anxiety. In path analysis of trauma subtypes, the effects of emotional abuse, physical abuse, and physical neglect as a child on adult dissociation were found to be fully mediated by attachment anxiety. The effect of sexual abuse on dissociation was mediated by a synergistic effect from both attachment anxiety and attachment avoidance. Regarding emotional neglect, a countervailing interaction was discovered between the direct and indirect effects thereof on dissociation; the indirect effect of emotional neglect on dissociation was partially mediated by attachment insecurity. Specific aspects of attachment insecurity may help explain the relationships between individual forms of childhood trauma and adult dissociative symptoms. Tailored treatments based on affected areas of attachment insecurity may improve outcomes among patients with dissociative symptoms and a history of childhood trauma.

Prototype Willingness Model Drinking Cognitions Mediate Personalized Normative Feedback Efficacy.

PubMed

Lewis, Melissa A; Litt, Dana M; Tomkins, Mary; Neighbors, Clayton

2017-05-01

Personalized normative feedback (PNF) interventions have been shown to be efficacious at reducing college student drinking. Because descriptive norms have been shown to mediate PNF efficacy, the current study focused on examining additional prototype willingness model social reaction cognitions, namely, prototypes and willingness, as mediators of intervention efficacy. We expected the PNF interventions to be associated with increased prototype favorability of students who do not drink, which would in turn be associated with decreased willingness to drink and subsequently, less drinking. The current study included 622 college students (53.2% women; 62% Caucasian) who reported one or more heavy drinking episodes in the past month and completed baseline and three-month follow-up assessments. As posited by the framework of the prototype willingness model, sequential mediation analyses were conducted to evaluate increases in abstainer prototype favorability on willingness on drinking, and subsequently willingness to drink on drinking behavior. Mediation results revealed significant indirect effects of PNF on three-month drinking through three-month prototypes and willingness, indicating that the social reaction pathway of the prototype willingness model was supported. Findings have important implications for PNF interventions aiming to reduce high-risk drinking among college students. Study findings suggest that we should consider looking at additional socially-based mediators of PNF efficacy in addition to perceived descriptive norms.

Prototype Willingness Model Drinking Cognitions Mediate Personalized Normative Feedback Efficacy

PubMed Central

Litt, Dana M.; Tomkins, Mary; Neighbors, Clayton

2017-01-01

Personalized normative feedback (PNF) interventions have been shown to be efficacious at reducing college student drinking. Because descriptive norms have been shown to mediate PNF efficacy, the current study focused on examining additional prototype willingness model social reaction cognitions, namely, prototypes and willingness, as mediators of intervention efficacy. We expected the PNF interventions to be associated with increased prototype favorability of students who do not drink, which would in turn be associated with decreased willingness to drink and subsequently, less drinking. The current study included 622 college students (53.2% women; 62% Caucasian) who reported one or more heavy drinking episodes in the past month and completed baseline and three-month follow-up assessments. As posited by the framework of the prototype willingness model, sequential mediation analyses were conducted to evaluate increases in abstainer prototype favorability on willingness on drinking, and subsequently willingness to drink on drinking behavior. Mediation results revealed significant indirect effects of PNF on three-month drinking through three-month prototypes and willingness, indicating that the social reaction pathway of the prototype willingness model was supported. Findings have important implications for PNF interventions aiming to reduce high-risk drinking among college students. Study findings suggest that we should consider looking at additional socially-based mediators of PNF efficacy in addition to perceived descriptive norms. PMID:27995431

Two-step estimation in ratio-of-mediator-probability weighted causal mediation analysis.

PubMed

Bein, Edward; Deutsch, Jonah; Hong, Guanglei; Porter, Kristin E; Qin, Xu; Yang, Cheng

2018-04-15

This study investigates appropriate estimation of estimator variability in the context of causal mediation analysis that employs propensity score-based weighting. Such an analysis decomposes the total effect of a treatment on the outcome into an indirect effect transmitted through a focal mediator and a direct effect bypassing the mediator. Ratio-of-mediator-probability weighting estimates these causal effects by adjusting for the confounding impact of a large number of pretreatment covariates through propensity score-based weighting. In step 1, a propensity score model is estimated. In step 2, the causal effects of interest are estimated using weights derived from the prior step's regression coefficient estimates. Statistical inferences obtained from this 2-step estimation procedure are potentially problematic if the estimated standard errors of the causal effect estimates do not reflect the sampling uncertainty in the estimation of the weights. This study extends to ratio-of-mediator-probability weighting analysis a solution to the 2-step estimation problem by stacking the score functions from both steps. We derive the asymptotic variance-covariance matrix for the indirect effect and direct effect 2-step estimators, provide simulation results, and illustrate with an application study. Our simulation results indicate that the sampling uncertainty in the estimated weights should not be ignored. The standard error estimation using the stacking procedure offers a viable alternative to bootstrap standard error estimation. We discuss broad implications of this approach for causal analysis involving propensity score-based weighting. Copyright © 2018 John Wiley & Sons, Ltd.

Ascomycin macrolactam derivative SDZ ASM 981 inhibits the release of granule-associated mediators and of newly synthesized cytokines in RBL 2H3 mast cells in an immunophilin-dependent manner.

PubMed

Hultsch, T; Müller, K D; Meingassner, J G; Grassberger, M; Schopf, R E; Knop, J

1998-09-01

Mast cells play an important role in the pathological development of many inflammatory and allergic diseases and inhibition of mast cell activation is a potential target for therapeutic intervention. Therefore, the effect of the novel ascomycin macrolactam derivative SDZ ASM 981 on Fc epsilonRI-mediated activation of rat basophilic leukemia (RBL) cells, as a model for mast cell activation, was investigated. First, the ability to inhibit different mast cell immunophilins in vitro was tested. Using recombinant macrophilin-12 (FKBP-12), inhibition of rotamase activity with an IC50 of approximately 6 nM was observed. The rotamase activity of cyclophilin A (18 kDa) was not affected. Secondly, the effect of SDZ ASM 981 on Fc epsilonRI-mediated mast cell activation was investigated in the RBL cell model. SDZ ASM 981 inhibited exocytosis of preformed mediators (e.g. serotonin) with an IC50 of approximately 30 nM. Transcription and release of newly synthesized mediators (e.g. TNF-alpha) was inhibited with an IC50 of approximately 100 nM. The inhibitory effect of SDZ ASM 981 was antagonized by rapamycin. We conclude that SDZ ASM 981 is a potent inhibitor of Fc epsilonRI-mediated activation of mast cells in vitro. The mechanism of action involves formation of (calcineurin) inhibitory complexes with macrophilins. We suggest that this inhibitory action on mast cells might contribute to the antiinflammatory effect of SDZ ASM 981 observed in vivo (e.g. in aptopic dermatitis and psoriasis).

The Mediating Role of Interpersonal Competence between Adolescents' Empathy and Friendship Quality: A Dyadic Approach

ERIC Educational Resources Information Center

Chow, Chong Man; Ruhl, Holly; Buhrmester, Duane

2013-01-01

The current study examined the effect of empathy on friendship quality in the context of dyadic same-sex friendships, and how such an effect might be mediated by interpersonal competence. A special version of the actor-partner interdependence model (APIM) was used to examine this hypothesis in 146 same-sex friend dyads in 10th grade. Results…

The Mediating Effects of Work-Related Stress on Mentoring Functions and Job Attitude: A Comparison of General and Special Education Teachers

ERIC Educational Resources Information Center

Rabenhorst, Greg A.

2011-01-01

The current study is designed to investigate the mediating effects of work-related stress on the relationship between mentoring functions (i.e., career support, psychosocial support, and role modeling) and measures of job attitude (i.e., job satisfaction and organizational commitment). Mentoring is widely used as a means of assisting in the new…

Suicidal ideation among suburban adolescents: The influence of school bullying and other mediating risk factors.

PubMed

Lardier, David T; Barrios, Veronica R; Garcia-Reid, Pauline; Reid, Robert J

2016-10-01

Prior research has identified multiple factors that influence suicidal ideation (SI) among bullied youth. The effects of school bullying on SI cannot be considered in isolation. In this study, we examined the influence of school bullying on SI, through a constellation of risks, which include depressive and anxiety symptoms, family conflict, and alcohol, tobacco, and other drug (ATOD) use. We also provide recommendations for therapists working with bullied youth. Our sample consisted of 488 adolescents (ages 10-18 years) from a northern New Jersey, United States suburban community. Students were recruited through the district's physical education and health classes. Students responded to multiple measures, which included family cohesion/conflict, ATOD use, mental health indicators, SI, and school bullying experiences. Following preliminary analyses, several logistic regression models were used to assess the direct influence of bullying on SI, as well as the unique effects of family conflict, depressive and anxiety symptoms, and substance use. In addition, a parallel multiple mediating model with the PROCESS macro in SPSS was used to further assess mediating effects. Logistic regression results indicated that school bullying increased the odds of SI among males and females and that when mediating variables were added to the model, bullying no longer had a significant influence on SI. Overall, these results display that for both males and females, school bullying was a significant contributor to SI. Results from the parallel multiple mediating model further illustrated the mediating effects that family conflict, depression, and ATOD use had between bullying and SI. Some variation was noted based on gender. This study draws attention to the multiple experiences associated with school bullying on SI, and how these results may differ by gender. The results of this study are particularly important for those working directly and indirectly with bullied youth. Therapists that engage bullied youth need to consider the multiple spheres of influence that may increase SI among male and female clients. To holistically and adequately assess SI among bullied youth, therapists must also consider how these mechanisms vary between gender groups.

Job stress, unwinding and drinking in transit operators.

PubMed

Delaney, William P; Grube, Joel W; Greiner, Birgit; Fisher, June M; Ragland, David R

2002-07-01

This study tests the spillover model of the effects of work stress on after-work drinking, using the variable "length of time to unwind" as a mediator. A total of 1,974 transit operators were contacted and 1,553 (79%) of them participated in a personal interview. Complete data on the variables in this analysis were available for 1,208 respondents (84% men). Using latent variable structural equation modeling, a model was tested that predicted that daily job problems, skipped meals and less social support from supervisor would increase alcohol consumption through the mediator, length of time to unwind and relax after work. Increased alcohol consumption was, in turn, hypothesized to increase drinking problems. As predicted, skipped meals and daily job problems increased length of time to unwind and had an indirect positive relationship with overall drinking, even when controlling for drinking norms and demographic variables. Overall drinking was positively associated with drinking problems. Supervisor support at work, however, did not significantly influence length of time to unwind. Difficulty unwinding (longer time to unwind) did not have direct effects on drinking problems; however, indirect effects through overall drinking were observed. These results provide preliminary support for the mediating role of length of time to unwind and relax after work in a spillover model of the stress-drinking relationship. This research introduces a new mediator and empirical links between job problems, length of time to unwind, drinking and drinking problems, which ground more substantively the domains of work stress and alcohol consumption.

Power in Bayesian Mediation Analysis for Small Sample Research

PubMed Central

Miočević, Milica; MacKinnon, David P.; Levy, Roy

2018-01-01

It was suggested that Bayesian methods have potential for increasing power in mediation analysis (Koopman, Howe, Hollenbeck, & Sin, 2015; Yuan & MacKinnon, 2009). This paper compares the power of Bayesian credibility intervals for the mediated effect to the power of normal theory, distribution of the product, percentile, and bias-corrected bootstrap confidence intervals at N≤ 200. Bayesian methods with diffuse priors have power comparable to the distribution of the product and bootstrap methods, and Bayesian methods with informative priors had the most power. Varying degrees of precision of prior distributions were also examined. Increased precision led to greater power only when N≥ 100 and the effects were small, N < 60 and the effects were large, and N < 200 and the effects were medium. An empirical example from psychology illustrated a Bayesian analysis of the single mediator model from prior selection to interpreting results. PMID:29662296

Power in Bayesian Mediation Analysis for Small Sample Research.

PubMed

Miočević, Milica; MacKinnon, David P; Levy, Roy

2017-01-01

It was suggested that Bayesian methods have potential for increasing power in mediation analysis (Koopman, Howe, Hollenbeck, & Sin, 2015; Yuan & MacKinnon, 2009). This paper compares the power of Bayesian credibility intervals for the mediated effect to the power of normal theory, distribution of the product, percentile, and bias-corrected bootstrap confidence intervals at N≤ 200. Bayesian methods with diffuse priors have power comparable to the distribution of the product and bootstrap methods, and Bayesian methods with informative priors had the most power. Varying degrees of precision of prior distributions were also examined. Increased precision led to greater power only when N≥ 100 and the effects were small, N < 60 and the effects were large, and N < 200 and the effects were medium. An empirical example from psychology illustrated a Bayesian analysis of the single mediator model from prior selection to interpreting results.

Therapeutic neovascularization by nanotechnology-mediated cell-selective delivery of pitavastatin into the vascular endothelium.

PubMed

Kubo, Mitsuki; Egashira, Kensuke; Inoue, Takahiro; Koga, Jun-ichiro; Oda, Shinichiro; Chen, Ling; Nakano, Kaku; Matoba, Tetsuya; Kawashima, Yoshiaki; Hara, Kaori; Tsujimoto, Hiroyuki; Sueishi, Katsuo; Tominaga, Ryuji; Sunagawa, Kenji

2009-06-01

Recent clinical studies of therapeutic neovascularization using angiogenic growth factors demonstrated smaller therapeutic effects than those reported in animal experiments. We hypothesized that nanoparticle (NP)-mediated cell-selective delivery of statins to vascular endothelium would more effectively and integratively induce therapeutic neovascularization. In a murine hindlimb ischemia model, intramuscular injection of biodegradable polymeric NP resulted in cell-selective delivery of NP into the capillary and arteriolar endothelium of ischemic muscles for up to 2 weeks postinjection. NP-mediated statin delivery significantly enhanced recovery of blood perfusion to the ischemic limb, increased angiogenesis and arteriogenesis, and promoted expression of the protein kinase Akt, endothelial nitric oxide synthase (eNOS), and angiogenic growth factors. These effects were blocked in mice administered a nitric oxide synthase inhibitor, or in eNOS-deficient mice. NP-mediated cell-selective statin delivery may be a more effective and integrative strategy for therapeutic neovascularization in patients with severe organ ischemia.

Neutrophils kill pulmonary endothelial cells by a hydrogen-peroxide-dependent pathway. An in vitro model of neutrophil-mediated lung injury.

PubMed

Martin, W J

1984-08-01

Neutrophil-mediated injury to lung parenchymal cells has been proposed as an important step in the pathogenesis of many acute and chronic lung disorders. As an in vitro model of neutrophil-mediated injury, this study used activated human neutrophils as effector cells in an 18-h cytotoxicity assay with 51Cr-labeled bovine pulmonary artery endothelial cells serving as target cells. Neutrophils effectively injured pulmonary endothelial cells, expressed as cytotoxic index (CI), of 63.8 +/- 5.4, and this injury could be significantly reduced by several agents, including 1% dimethyl sulfoxide (CI, 51.3 +/- 3.7), 50 micrograms/ml ascorbic acid (CI, 40.8 +/- 4.7), and especially 1,100 U/ml catalase (CI, 14.3 +/- 4.1). As cell-free models of neutrophil-mediated endothelial cell injury, H2O2 (30 microM), O2- (generated by 0.5 mU xanthine oxidase), and the myeloperoxidase-dependent (0.32 U) hypohalite ion were each capable of injuring the target cells with CI of 6.21 +/- 2.8, 53.6 +/- 5.3, and 21.2 +/- 1.5, respectively. Catalase was effective in reducing the injurious effect of each of these oxidant-generating systems (p less than 0.01, all comparisons), confirming the important role for H2O2 in the mediation of this injury. The data indicate that neutrophils are capable of killing pulmonary endothelial cells by a pathway largely dependent on the generation of H2O2, and suggest the possibility that removal of H2O2 from the alveolar structures in subjects with these disorder might be an effective future therapeutic approach.

Effects of a combined parent-student alcohol prevention program on intermediate factors and adolescents' drinking behavior: A sequential mediation model.

PubMed

Koning, Ina M; Maric, Marija; MacKinnon, David; Vollebergh, Wilma A M

2015-08-01

Previous work revealed that the combined parent-student alcohol prevention program (PAS) effectively postponed alcohol initiation through its hypothesized intermediate factors: increase in strict parental rule setting and adolescents' self-control (Koning, van den Eijnden, Verdurmen, Engels, & Vollebergh, 2011). This study examines whether the parental strictness precedes an increase in adolescents' self-control by testing a sequential mediation model. A cluster randomized trial including 3,245 Dutch early adolescents (M age = 12.68, SD = 0.50) and their parents randomized over 4 conditions: (1) parent intervention, (2) student intervention, (3) combined intervention, and (4) control group. Outcome measure was amount of weekly drinking measured at age 12 to 15; baseline assessment (T0) and 3 follow-up assessments (T1-T3). Main effects of the combined and parent intervention on weekly drinking at T3 were found. The effect of the combined intervention on weekly drinking (T3) was mediated via an increase in strict rule setting (T1) and adolescents' subsequent self-control (T2). In addition, the indirect effect of the combined intervention via rule setting (T1) was significant. No reciprocal sequential mediation (self-control at T1 prior to rules at T2) was found. The current study is 1 of the few studies reporting sequential mediation effects of youth intervention outcomes. It underscores the need of involving parents in youth alcohol prevention programs, and the need to target both parents and adolescents, so that change in parents' behavior enables change in their offspring. (c) 2015 APA, all rights reserved).

Patient Health Communication Mediating Effects Between Gastrointestinal Symptoms and Gastrointestinal Worry in Pediatric Inflammatory Bowel Disease.

PubMed

Varni, James W; Shulman, Robert J; Self, Mariella M; Saeed, Shehzad A; Patel, Ashish S; Nurko, Samuel; Neigut, Deborah A; Saps, Miguel; Zacur, George M; Dark, Chelsea V; Bendo, Cristiane B; Pohl, John F

2017-05-01

To investigate the effects of patient health communication regarding their inflammatory bowel disease (IBD) to their health care providers and significant others in their daily life as a mediator in the relationship between gastrointestinal symptoms and gastrointestinal worry in pediatric patients. The Pediatric Quality of Life Inventory Gastrointestinal Symptoms, Gastrointestinal Worry, and Communication Scales, and Pediatric Quality of Life Inventory 4.0 Generic Core Scales were completed in a 9-site study by 252 pediatric patients with IBD. Gastrointestinal Symptoms Scales measuring stomach pain, constipation, or diarrhea and patient communication were tested for bivariate and multivariate linear associations with Gastrointestinal Worry Scales specific to patient worry about stomach pain or bowel movements. Mediational analyses were conducted to test the hypothesized mediating effects of patient health communication as an intervening variable in the relationship between gastrointestinal symptoms and gastrointestinal worry. The predictive effects of gastrointestinal symptoms on gastrointestinal worry were mediated in part by patient health communication with health care providers/significant others in their daily life. In predictive models using multiple regression analyses, the full conceptual model of demographic variables, gastrointestinal symptoms (stomach pain, constipation, or diarrhea), and patient communication significantly accounted for 46, 43, and 54 percent of the variance in gastrointestinal worry (all Ps < 0.001), respectively, reflecting large effect sizes. Patient health communication explains in part the effects of gastrointestinal symptoms on gastrointestinal worry in pediatric patients with IBD. Supporting patient disease-specific communication to their health care providers and significant others may improve health-related quality of life for pediatric patients with IBD.

MC EMiNEM maps the interaction landscape of the Mediator.

PubMed

Niederberger, Theresa; Etzold, Stefanie; Lidschreiber, Michael; Maier, Kerstin C; Martin, Dietmar E; Fröhlich, Holger; Cramer, Patrick; Tresch, Achim

2012-01-01

The Mediator is a highly conserved, large multiprotein complex that is involved essentially in the regulation of eukaryotic mRNA transcription. It acts as a general transcription factor by integrating regulatory signals from gene-specific activators or repressors to the RNA Polymerase II. The internal network of interactions between Mediator subunits that conveys these signals is largely unknown. Here, we introduce MC EMiNEM, a novel method for the retrieval of functional dependencies between proteins that have pleiotropic effects on mRNA transcription. MC EMiNEM is based on Nested Effects Models (NEMs), a class of probabilistic graphical models that extends the idea of hierarchical clustering. It combines mode-hopping Monte Carlo (MC) sampling with an Expectation-Maximization (EM) algorithm for NEMs to increase sensitivity compared to existing methods. A meta-analysis of four Mediator perturbation studies in Saccharomyces cerevisiae, three of which are unpublished, provides new insight into the Mediator signaling network. In addition to the known modular organization of the Mediator subunits, MC EMiNEM reveals a hierarchical ordering of its internal information flow, which is putatively transmitted through structural changes within the complex. We identify the N-terminus of Med7 as a peripheral entity, entailing only local structural changes upon perturbation, while the C-terminus of Med7 and Med19 appear to play a central role. MC EMiNEM associates Mediator subunits to most directly affected genes, which, in conjunction with gene set enrichment analysis, allows us to construct an interaction map of Mediator subunits and transcription factors.

Examination of the Effects of Self-Modeling on Autobiographical Memory

ERIC Educational Resources Information Center

Margiano, Suzanne G.; Kehle, Thomas J.; Bray, Melissa A.; Nastasi, Bonnie K.; DeWees, Kayla

2009-01-01

The intent of this preliminary study is to explore the effectiveness of self-modeling in altering maladaptive behavior in children through the mediating effect of modifying their autobiographical memories of their dysfunctional behaviors. We proposed that the alteration of inappropriate classroom behaviors afforded by the self-modeling…

Subjective health complaints, functional ability, fear avoidance beliefs, and days on sickness benefits after work rehabilitation - a mediation model.

PubMed

Øyeflaten, Irene; Opsahl, Jon; Eriksen, Hege R; Braathen, Tore Norendal; Lie, Stein Atle; Brage, Søren; Ihlebæk, Camilla M; Breivik, Kyrre

2016-05-23

Long-term sick leave and withdrawal from working life is a concern in western countries. In Norway, comprehensive inpatient work rehabilitation may be offered to sick listed individuals at risk of long-term absence from work. Knowledge about prognostic factors for work outcomes after long-term sick leave and work rehabilitation is still limited. The aim of this study was to test a mediation model for various hypothesized biopsychosocial predictors of continued sick leave after inpatient work rehabilitation. One thousand one hundred fifty-five participants on long-term sick leave from eight different work rehabilitation clinics answered comprehensive questionnaires at arrival to the clinic, and were followed with official register data on sickness benefits for 3 years. Structural equation models were conducted, with days on sickness benefits after work rehabilitation as the outcome. Fear avoidance beliefs for work mediated the relation between both musculoskeletal complaints and education on days on sickness benefits after work rehabilitation. The relation between musculoskeletal complaints and fear avoidance beliefs for work was furthermore fully mediated by poor physical function. Previous sick leave had a strong independent effect on continued sick leave after work rehabilitation. Fear avoidance beliefs for work did not mediate the small effect of pseudoneurological complaints on continued sick leave. Poor coping/interaction ability was neither related to continued sick leave nor fear avoidance beliefs for work. The mediation model was partly supported by the data, and provides some possible new insight into how fear avoidance beliefs for work and functional ability may intervene with subjective health complaints and days on sickness benefits after work rehabilitation.

How Online Basic Psychological Need Satisfaction Influences Self-Disclosure Online among Chinese Adolescents: Moderated Mediation Effect of Exhibitionism and Narcissism.

PubMed

Liu, Ying; Liu, Ru-De; Ding, Yi; Wang, Jia; Zhen, Rui; Xu, Le

2016-01-01

Under the basic framework of self-determination theory, the present study examined a moderated mediation model in which exhibitionism mediated the relationship between online basic psychological need satisfaction and self-disclosure on the mobile Internet, and this mediation effect was moderated by narcissism. A total of 296 Chinese middle school students participated in this research. The results revealed that exhibitionism fully mediated the association between online competence need satisfaction and self-disclosure on the mobile net, and partly mediated the association between online relatedness need satisfaction and self-disclosure on the mobile net. The mediating path from online basic psychological need satisfaction (competence and relatedness) to exhibitionism was moderated by narcissism. Compared to the low level of narcissism, online competence need satisfaction had a stronger predictive power on exhibitionism under the high level of narcissism condition. In contrast, online relatedness need satisfaction had a weaker predictive power on exhibitionism.

How Online Basic Psychological Need Satisfaction Influences Self-Disclosure Online among Chinese Adolescents: Moderated Mediation Effect of Exhibitionism and Narcissism

PubMed Central

Liu, Ying; Liu, Ru-De; Ding, Yi; Wang, Jia; Zhen, Rui; Xu, Le

2016-01-01

Under the basic framework of self-determination theory, the present study examined a moderated mediation model in which exhibitionism mediated the relationship between online basic psychological need satisfaction and self-disclosure on the mobile Internet, and this mediation effect was moderated by narcissism. A total of 296 Chinese middle school students participated in this research. The results revealed that exhibitionism fully mediated the association between online competence need satisfaction and self-disclosure on the mobile net, and partly mediated the association between online relatedness need satisfaction and self-disclosure on the mobile net. The mediating path from online basic psychological need satisfaction (competence and relatedness) to exhibitionism was moderated by narcissism. Compared to the low level of narcissism, online competence need satisfaction had a stronger predictive power on exhibitionism under the high level of narcissism condition. In contrast, online relatedness need satisfaction had a weaker predictive power on exhibitionism. PMID:27616999

Relationship between mediation analysis and the structured life course approach.

PubMed

Howe, Laura D; Smith, Andrew D; Macdonald-Wallis, Corrie; Anderson, Emma L; Galobardes, Bruna; Lawlor, Debbie A; Ben-Shlomo, Yoav; Hardy, Rebecca; Cooper, Rachel; Tilling, Kate; Fraser, Abigail

2016-08-01

Many questions in life course epidemiology involve mediation and/or interaction because of the long latency period between exposures and outcomes. In this paper, we explore how mediation analysis (based on counterfactual theory and implemented using conventional regression approaches) links with a structured approach to selecting life course hypotheses. Using theory and simulated data, we show how the alternative life course hypotheses assessed in the structured life course approach correspond to different combinations of mediation and interaction parameters. For example, an early life critical period model corresponds to a direct effect of the early life exposure, but no indirect effect via the mediator and no interaction between the early life exposure and the mediator. We also compare these methods using an illustrative real-data example using data on parental occupational social class (early life exposure), own adult occupational social class (mediator) and physical capability (outcome). © The Author 2016. Published by Oxford University Press on behalf of the International Epidemiological Association.

Learning the names of people: the role of image mediators.

PubMed

Groninger, L D; Groninger, D H; Stiens, J

1995-06-01

Four experiments are reported involving the effects of bizarre and common imagery mediation techniques on the learning and 1-week retention of surnames, given videotaped faces as cues. The videotapes contained 24 undergraduates who were photographed from about the chest up, and who introduced themselves at a 20-second rate. Experiment 1 showed that for both concrete and abstract names, immediate recall of the list was better under imagery mediation instructions than under control instructions. Experiment 2 studied the same conditions using immediate recognition memory of the list as a retrieval measure for the names, and found, despite ceiling effects, that bizarre imagery instructions facilitated recognition for concrete names. Experiment 3 showed that immediate recall could be improved if subjects were given an image mediator for every face-name pair as opposed to generating their own image mediators. Experiment 4 yielded three important findings: (a) 84% of the variance in the 1-week retention of initially recalled names was explained by the presence of absence of the original mediator during 1-week recall; (b) instructions to form image mediators facilitate recall not because image mediators are more effective than other types of mediators, but because they increase the likelihood that a mediator will be formed; (c) 1-week retention could be enhanced with an increased focus during encoding on the points where the mediation process is most likely to fail. The results of these studies are discussed within the context of mediation model wherein recall can fail at any of four stages.

A multi-process model of self-regulation: influences of mindfulness, integrative self-knowledge and self-control in Iran.

PubMed

Ghorbani, Nima; Watson, P J; Farhadi, Mehran; Chen, Zhuo

2014-04-01

Self-regulation presumably rests upon multiple processes that include an awareness of ongoing self-experience, enduring self-knowledge and self-control. The present investigation tested this multi-process model using the Five-Facet Mindfulness Questionnaire (FFMQ) and the Integrative Self-Knowledge and Brief Self-Control Scales. Using a sample of 1162 Iranian university students, we confirmed the five-factor structure of the FFMQ in Iran and documented its factorial invariance across males and females. Self-regulatory variables correlated negatively with Perceived Stress, Depression, and Anxiety and positively with Self-Esteem and Satisfaction with Life. Partial mediation effects confirmed that self-regulatory measures ameliorated the disturbing effects of Perceived Stress. Integrative Self-Knowledge and Self-Control interacted to partially mediate the association of Perceived Stress with lower levels of Satisfaction with Life. Integrative Self-Knowledge, alone or in interaction with Self-Control, was the only self-regulation variable to display the expected mediation of Perceived Stress associations with all other measures. Self-Control failed to be implicated in self-regulation only in the mediation of Anxiety. These data confirmed the need to further examine this multi-process model of self-regulation. © 2014 International Union of Psychological Science.

The Association among Childhood Trauma, Pathological Dissociation and Gambling Severity in Casino Gamblers.

PubMed

Imperatori, Claudio; Innamorati, Marco; Bersani, Francesco Saverio; Imbimbo, Francesca; Pompili, Maurizio; Contardi, Anna; Farina, Benedetto

2017-01-01

The aim of the present study was to explore the role of pathological dissociation in mediating the association between childhood trauma (CT) and gambling severity. One hundred seventy-one (134 men and 37 women) gamblers recruited in gambling environments (i.e., two Italian casinos) have been enrolled in the study. Psychopathological assessments included the Childhood Trauma Questionnaire (CTQ), the Dissociative Experiences Scale-Taxon (DES-T), the South Oaks Gambling Screen (SOGS), the CAGE and the Hospital Anxiety and Depression Scale. A mediational model, analyzing the direct and indirect effects of CTQ on SOGS through the mediating role of DES-T, showed that the relation between CTQ and SOGS was fully mediated by DES-T scores (b = 0.07; se = 0.15; p < 0.001). This finding raises the possibility that CT explains gambling severity through the presence of pathological dissociative symptoms and dissociative pathogenetic processes. Copyright © 2015 John Wiley & Sons, Ltd. Gambling severity is associated with both childhood trauma and pathological dissociation in casino gamblers. A mediational model shows that the effect of childhood trauma on gambling severity is entirely mediated by pathological dissociation. From a clinical point of view, our results highlight the importance of assessing, and possibly treating, dissociative symptoms in individuals with gambling disorder. Copyright © 2015 John Wiley & Sons, Ltd.

Self-Stigma and Its Relationship with Victimization, Psychotic Symptoms and Self-Esteem among People with Schizophrenia Spectrum Disorders

PubMed Central

Horsselenberg, Ellen M. A.; van Busschbach, Jooske T.; Aleman, Andre; Pijnenborg, Gerdine H. M.

2016-01-01

Objective Self-stigma is highly prevalent in schizophrenia and can be seen as an important factor leading to low self-esteem. It is however unclear how psychological factors and actual adverse events contribute to self-stigma. This study empirically examines how symptom severity and the experience of being victimized affect both self-stigma and self-esteem. Methods Persons with a schizophrenia spectrum disorder (N = 102) were assessed with a battery of self-rating questionnaires and interviews. Structural equation modelling (SEM) was subsequently applied to test the fit of three models: a model with symptoms and victimization as direct predictors of self-stigma and negative self-esteem, a model with an indirect effect for symptoms mediated by victimization and a third model with a direct effect for negative symptoms and an indirect effect for positive symptoms mediated by victimization. Results Results showed good model fit for the direct effects of both symptoms and victimization: both lead to an increase of self-stigma and subsequent negative self-esteem. Negative symptoms had a direct association with self-stigma, while the relationship between positive symptoms and self-stigma was mediated by victimization. Conclusions Our findings suggest that symptoms and victimization may contribute to self-stigma, leading to negative self-esteem in individuals with a schizophrenia spectrum disorder. Especially for patients with positive symptoms victimization seems to be an important factor in developing self-stigma. Given the burden of self-stigma on patients and the constraining effects on societal participation and service use, interventions targeting victimization as well as self-stigma are needed. PMID:27783677

Self-Stigma and Its Relationship with Victimization, Psychotic Symptoms and Self-Esteem among People with Schizophrenia Spectrum Disorders.

PubMed

Horsselenberg, Ellen M A; van Busschbach, Jooske T; Aleman, Andre; Pijnenborg, Gerdine H M

2016-01-01

Self-stigma is highly prevalent in schizophrenia and can be seen as an important factor leading to low self-esteem. It is however unclear how psychological factors and actual adverse events contribute to self-stigma. This study empirically examines how symptom severity and the experience of being victimized affect both self-stigma and self-esteem. Persons with a schizophrenia spectrum disorder (N = 102) were assessed with a battery of self-rating questionnaires and interviews. Structural equation modelling (SEM) was subsequently applied to test the fit of three models: a model with symptoms and victimization as direct predictors of self-stigma and negative self-esteem, a model with an indirect effect for symptoms mediated by victimization and a third model with a direct effect for negative symptoms and an indirect effect for positive symptoms mediated by victimization. Results showed good model fit for the direct effects of both symptoms and victimization: both lead to an increase of self-stigma and subsequent negative self-esteem. Negative symptoms had a direct association with self-stigma, while the relationship between positive symptoms and self-stigma was mediated by victimization. Our findings suggest that symptoms and victimization may contribute to self-stigma, leading to negative self-esteem in individuals with a schizophrenia spectrum disorder. Especially for patients with positive symptoms victimization seems to be an important factor in developing self-stigma. Given the burden of self-stigma on patients and the constraining effects on societal participation and service use, interventions targeting victimization as well as self-stigma are needed.

Parenting Practices and Adolescent Sexual Behavior: A Longitudinal Study

ERIC Educational Resources Information Center

Bersamin, Melina; Todd, Michael; Fisher, Deborah A.; Hill, Douglas L.; Grube, Joel W.; Walker, Samantha

2008-01-01

The effects of parental attitudes, practices, and television mediation on adolescent sexual behaviors were investigated in a study of adolescent sexuality and media (N = 887). Confirmatory factor analyses supported an eight-factor parenting model with television mediation factors as constructs distinct from general parenting practices. Logistic…

The Relationship Between Challenging Behaviour, Cognitions and Stress in Mothers of Individuals with Intellectual Disabilities.

PubMed

Rose, John; Nelson, Lisa; Hardiman, Rebecca

2016-11-01

Cognitions are starting to receive more prominence as important when examining a number of factors including the topography of challenging behaviour. This study examined the relationships between maternal stress, challenging behaviour (aggressive and self-injurious behaviours) and parental cognitions and specifically whether maternal cognitions mediated the effect of challenging behaviour on parenting stress. 46 mothers of children and young adults with ID completed questionnaires regarding their child's challenging behaviour, maternal cognitions and stress. Significant correlations were found between challenging behaviour and maternal stress. The overall mediation models for aggression and self-injurious behaviour were significant. The Challenging Behaviour Perception Questionnaire: Consequences client subscale was the only independent significant mediator for both behaviours. Cognitions do play an important part in mediating the relationship between challenging behaviour and stress. Further research is needed to examine the similarities and differences between the mediation models for aggression and self-injurious behaviour.

Association between Body Image Dissatisfaction and Self-Rated Health, as Mediated by Physical Activity and Eating Habits: Structural Equation Modelling in ELSA-Brasil.

PubMed

de Oliveira da Silva, Patricia; Miguez Nery Guimarães, Joanna; Härter Griep, Rosane; Caetano Prates Melo, Enirtes; Maria Alvim Matos, Sheila; Del Carmem Molina, Maria; Maria Barreto, Sandhi; de Jesus Mendes da Fonseca, Maria

2018-04-18

This study investigated whether the association between body image dissatisfaction and poor self-rated health is mediated by insufficient physical activity and unhealthy eating habits. The participants were 6727 men and 8037 women from the baseline (2008–2010) of the Longitudinal Study of Adult Health (Estudo Longitudinal de Saúde do Adulto, ELSA-Brasil). Structural equation modelling was used. Associations were found between body image dissatisfaction and poor self-rated health in both sexes. Insufficient physical activity was a mediator. However, unhealthy eating habits were found to exert a mediator effect only via insufficient physical activity. Body image dissatisfaction was found to associate, both directly and possibly indirectly, with poor self-rated health, mediated by insufficient physical activity and unhealthy eating habits. Accordingly, encouraging physical activity and healthy eating can contribute to reducing body image dissatisfaction and favour better self-rated health.

Self-objectification, weight bias internalization, and binge eating in young women: Testing a mediational model.

PubMed

Mehak, Adrienne; Friedman, Aliza; Cassin, Stephanie E

2018-03-01

Self-objectification and weight bias internalization are two internalization processes that are positively correlated with binge eating among young women. However, the mechanisms underlying these relationships are understudied. Consistent with objectification theory, this study examined appearance anxiety and body shame as mediators between self-objectification, weight bias internalization and binge eating. Female undergraduates (N=102) completed self-report measures of self-objectification, weight bias internalization, appearance anxiety, body shame, and binge eating. Results indicated that women who self-objectified and internalized negative weight-related attitudes reported greater binge eating (r s =.43 and r s =.57, respectively) and these associations were mediated by the combined effects of body shame and appearance anxiety. The contrast between the two mediators was also significant, such that body shame emerged as a stronger mediator within both mediational models. Results demonstrated that these internalization processes contribute to negative affect in young women, which may in turn lead to binge eating. Copyright © 2018 Elsevier Ltd. All rights reserved.

Mediator-assisted decolorization and detoxification of textile dyes/dye mixture by Cyathus bulleri laccase.

PubMed

Chhabra, Meenu; Mishra, Saroj; Sreekrishnan, T R

2008-12-01

Laccase from basidiomycete fungus Cyathus bulleri was evaluated for its ability to decolorize a number of reactive and acidic dyes in the presence of natural and synthetic mediators. The extent of decolorization was monitored at different mediator/dye concentrations and incubation time. Among the synthetic mediators, 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) was effective at low mediator/dye ratios and resulted in 80-95% decolorization at rates that varied from 226 +/- 4 nmol min(-1) mg(-1) for Reactive Orange 1 to 1,333 +/- 15 nmol min(-1) mg(-1) for Reactive Red 198. Other synthetic mediators like 1-hydroxybenzotriazole and violuric acid showed both concentration- and time-dependent increases in percent decolorization. Natural mediators like vanillin, on the other hand, were found to be less effective on all the dyes except Reactive Orange 1. Computed rates of decolorization were about twofold lower than that with ABTS. The laccase-ABTS system also led to nearly 80% decolorization for the simulated dye mixture. No clear correlation between laccase activity on the mediator and its ability to decolorize dyes was found, but pH had a significant effect: Optimum pH for decolorization coincided with the optimum pH for mediator oxidation. The treated samples were also evaluated for toxicity in model microbial systems. The laccase-mediator system appears promising for treatment of textile wastewaters.

Sensitivity analysis for linear structural equation models, longitudinal mediation with latent growth models and blended learning in biostatistics education

NASA Astrophysics Data System (ADS)

Sullivan, Adam John

In chapter 1, we consider the biases that may arise when an unmeasured confounder is omitted from a structural equation model (SEM) and sensitivity analysis techniques to correct for such biases. We give an analysis of which effects in an SEM are and are not biased by an unmeasured confounder. It is shown that a single unmeasured confounder will bias not just one but numerous effects in an SEM. We present sensitivity analysis techniques to correct for biases in total, direct, and indirect effects when using SEM analyses, and illustrate these techniques with a study of aging and cognitive function. In chapter 2, we consider longitudinal mediation with latent growth curves. We define the direct and indirect effects using counterfactuals and consider the assumptions needed for identifiability of those effects. We develop models with a binary treatment/exposure followed by a model where treatment/exposure changes with time allowing for treatment/exposure-mediator interaction. We thus formalize mediation analysis with latent growth curve models using counterfactuals, makes clear the assumptions and extends these methods to allow for exposure mediator interactions. We present and illustrate the techniques with a study on Multiple Sclerosis(MS) and depression. In chapter 3, we report on a pilot study in blended learning that took place during the Fall 2013 and Summer 2014 semesters here at Harvard. We blended the traditional BIO 200: Principles of Biostatistics and created ID 200: Principles of Biostatistics and epidemiology. We used materials from the edX course PH207x: Health in Numbers: Quantitative Methods in Clinical & Public Health Research and used. These materials were used as a video textbook in which students would watch a given number of these videos prior to class. Using surveys as well as exam data we informally assess these blended classes from the student's perspective as well as a comparison of these students with students in another course, BIO 201: Introduction to Statistical Methods in Fall 2013 as well as students from BIO 200 in Fall semesters of 1992 and 1993. We then suggest improvements upon our original course designs and follow up with an informal look at how these implemented changes affected the second offering of the newly blended ID 200 in Summer 2014.

The mediating effect of self-reflection and learning effectiveness on clinical nursing performance in nursing students: A follow-up study.

PubMed

Pai, Hsiang-Chu; Ko, Hui-Ling; Eng, Cheng-Joo; Yen, Wen-Jiuan

The effectiveness of simulation learning and the effects of anxiety in the simulated situation have been understudied. In addition, research on the association between learning effectiveness and students' clinical care performance in the hospital setting is very limited in Taiwan. The aim of this study is to examine the mediating effect of self-reflection and simulation learning effectiveness on the clinical nursing performance of nursing students. A Prospective, longitudinal, and correlational design was used. The study was conducted from December 2014 to July 2015. Participants were 293 nursing students in southern Taiwan. A structural model was specified and tested using partial least squares structural equation modeling to examine the relationships between the variables. The results revealed that the model was robust in terms of its measurement quality (reliability, validity, and goodness of fit), with the data's explaining 38.3% of variance in nursing competence. As self-reflection and learning effectiveness were added into the structural model, the effect of anxiety on nursing competence was still significant, but the regression coefficient (β) estimate of -0.41 (p<0.05) changed to β=-0.15 (p<0.050),indicating that self-reflection and learning effectiveness mediated the relationship between anxiety and nursing competence. Nursing competence was negatively affected by anxiety and positively affected by self-reflection (β=0.49, p<0.05) and simulation learning effectiveness (β=0.10, p<0.05). The teacher's encouraging learning can have a positive influence on students' self-reflection and learning effectiveness, which then decreases the effect of anxiety on nursing competence and further promotes students' clinical care ability. Copyright © 2017 Elsevier Inc. All rights reserved.

The Association of Work Stress and Glycemic Status Is Partially Mediated by Autonomic Nervous System Function: Cross-Sectional Results from the Mannheim Industrial Cohort Study (MICS)

PubMed Central

Koenig, Julian; Li, Jian; Mauss, Daniel; Hoffmann, Kristina; Schmidt, Burkhard; Fischer, Joachim E.; Thayer, Julian F.

2016-01-01

Background Work stress is associated with an increased risk of pre-diabetes, Type 2 diabetes, and inflammation, as well as decreased autonomic nervous system function as measured, for example, via heart rate variability. We investigated the extent to which the association between work stress and glycemic status is mediated by vagally-mediated heart rate variability (vmHRV) and/or inflammation. Methods Cross-sectional data from the Mannheim Industrial Cohort Study (MICS) with 9,937 participants were analyzed. The root mean squared successive differences (RMSSD) from long-term heart rate monitoring during work and night time periods was used to index vmHRV. Fasting plasma glucose and glycosylated hemoglobin were assessed to determine glycemic status. High sensitive C-reactive protein levels were observed as a measure of systemic inflammation and the Effort-Reward-Imbalance scale was used to evaluate work stress. Mediation models were adjusted for age, sex, and occupational status, and estimations were bootstrapped (5,000 replications). Results Effort-Reward-Imbalance was significantly negatively associated with RMSSD and both glycosylated hemoglobin and fasting plasma glucose during both work and night time periods. Effort-Reward-Imbalance was observed to have a significant direct effect on glycosylated hemoglobin and significant indirect effects, through RMSSD, on both glycemic measures during both time periods. Introducing C-reactive protein as a further mediator to the model did not alter the indirect effects observed. C-reactive protein, as an exclusive mediator, was observed to have smaller direct and indirect effects on the glycemic measures as compared to when Effort-Reward-Imbalance was included in the model. Conclusions Our results suggest that the association between work stress and glycemic status is partially mediated through vmHRV independent of systemic inflammation as measured by C-reactive protein. We conclude that work stress may be an additional factor that promotes development of hyperglycemic-metabolic states. If supported by prospective evidence, these results may lead to new approaches for primary prevention of hyperglycemia in the workplace. PMID:27532642

Adolescent socioeconomic status and depressive symptoms in later life: Evidence from structural equation models.

PubMed

Pino, Elizabeth C; Damus, Karla; Jack, Brian; Henderson, David; Milanovic, Snezana; Kalesan, Bindu

2018-01-01

The complex association between socioeconomic status (SES) and depressive symptoms is not entirely understood and the existing literature does not address the relationship between early-life SES and later-life depression from a life-course perspective, incorporating mediating events. Using data from the Wisconsin Longitudinal Study, we employed structural equation modeling to examine how SES measured at age 18 affects depressive symptoms at age 54 directly and through mediating variables college graduation, marriage, and household income level at age 36. The total effect of adolescent SES on later-life depressive symptoms is largely mediated through college graduation. Our final model was driven by the effects of women. The variables contributing most to depressive symptoms in women were the direct effect of being raised in a home with a low SES and the indirect effect of low adolescent SES mediated through non-completion of college. Cohort was exclusively comprised of white, high school graduates born in 1939 (± 2 years). In our analysis we assume that missing values are missing at random (MAR); however, attrition both from death (excluded from our population) and from non-response could be associated with depression, i.e. missing not at random (MNAR). This study demonstrates the impact of completion of college, particularly among women, and supports the social mobility hypothesis to explain the relationship between adolescent socioeconomic circumstances and late-life health. Copyright © 2017 Elsevier B.V. All rights reserved.

Attachment orientations as mediators in the intergenerational transmission of marital satisfaction.

PubMed

Jarnecke, Amber M; South, Susan C

2013-08-01

Previous research suggests that there is an intergenerational transmission of marital satisfaction, such that parents' marital satisfaction predicts their adult child's marital satisfaction. The mechanisms that explain this phenomenon remain relatively unknown. In the current study, we examined the role of parent-child attachment orientations and romantic relationship attachment orientations as mediators in the intergenerational transmission of marital satisfaction. Participants (N = 199) were cohabiting newlywed couples who had been married for 12 months or less. All participants separately completed measures of own marital satisfaction, attachment orientations to romantic partners, attachment orientations to rearing parents, and perceptions of parents' marital satisfaction. Data was analyzed using the actor-partner interdependence model in a structural equation modeling framework to account for the nonindependent nature of the data. This allowed for examination of gender differences across husbands and wives and provided overall fit of the hypothesized model. Results supported a partially mediating effect of parent-child attachment and romantic partner attachment on the intergenerational transmission of marital satisfaction, although effects differed by gender. For husbands, the direct effect from parents' marital satisfaction to own satisfaction was partially mediated through anxious attachment styles. There was no direct effect from parents to own marital satisfaction for wives; however, there were significant links from parent's satisfaction to attachment orientations in childhood and adulthood, which in turn impacted wives satisfaction. Findings from this study provide an integrated look at the implications that attachment has on the intergenerational transmission of marital functioning. © 2013 American Psychological Association

A mouse model of androgenetic alopecia.

PubMed

Crabtree, Judy S; Kilbourne, Edward J; Peano, Bryan J; Chippari, Susan; Kenney, Thomas; McNally, Christopher; Wang, Wei; Harris, Heather A; Winneker, Richard C; Nagpal, Sunil; Thompson, Catherine C

2010-05-01

Androgenetic alopecia (AGA), commonly known as male pattern baldness, is a form of hair loss that occurs in both males and females. Although the exact cause of AGA is not known, it is associated with genetic predisposition through traits related to androgen synthesis/metabolism and androgen signaling mediated by the androgen receptor (AR). Current therapies for AGA show limited efficacy and are often associated with undesirable side effects. A major hurdle to developing new therapies for AGA is the lack of small animal models to support drug discovery research. Here, we report the first rodent model of AGA. Previous work demonstrating that the interaction between androgen-bound AR and beta-catenin can inhibit Wnt signaling led us to test the hypothesis that expression of AR in hair follicle cells could interfere with hair growth in an androgen-dependent manner. Transgenic mice overexpressing human AR in the skin under control of the keratin 5 promoter were generated. Keratin 5-human AR transgenic mice exposed to high levels of 5alpha-dihydrotestosterone showed delayed hair regeneration, mimicking the AGA scalp. This effect is AR mediated, because treatment with the AR antagonist hydroxyflutamide inhibited the effect of dihydrotestosterone on hair growth. These results support the hypothesis that androgen-mediated hair loss is AR dependent and suggest that AR and beta-catenin mediate this effect. These mice can now be used to test new therapeutic agents for the treatment of AGA, accelerating the drug discovery process.

Tobacco counter-advertising: a review of the literature and a conceptual model for understanding effects.

PubMed

Agostinelli, Gina; Grube, Joel W

2003-01-01

The tobacco counter-advertising literature is reviewed as it relates to basic process questions concerning what makes counter-advertisements effective. Limitations in addressing (a) counter-advertisement content and the psychological mediators targeted, (b) counter-advertisement style and the affective reactions targeted, (c) prior smoking experience, and (d) other audience factors are enumerated. A theoretical model based on alcohol advertising research is presented to address those limitations. The model addresses the practical research question of predicting when tobacco counter-advertising will work by examining the independent influence of each of these enumerated factors, as well as how these factors operate in concert, qualifying each other. The model also addresses the process question of explaining how counter-advertising works by identifying affective and cognitive processes as mediators. By understanding the processes that underlie the qualified findings, one can better advise the designers of tobacco counter-advertisements how to be more effective.

The Mediating Roles of Hostility and Dissociation in the Relationship Between Sexual Assault and Suicidal Thinking in College Students.

PubMed

Keefe, Kristy M; Hetzel-Riggin, Melanie D; Sunami, Naoyuki

2017-03-01

Sexual assault and suicide are two serious public health concerns. Research has documented the relationship between sexual assault and suicidal thinking and attempts; however, limited research explores the more multifaceted relationships between posttraumatic stress reactions and suicidal ideation in college students through unsuccessful modulation of emotion. The authors hypothesized a mediation model where the relationship between sexual assault and suicidal ideation is mediated by dissociation and hostility. In total, 1,677 undergraduate students were administered modified versions of the Traumatic Life Events Questionnaire (TLEQ), Symptom Checklist-90-Revised (SCL-90-R), and Peritraumatic Dissociative Experiences Questionnaire (PDEQ). The results revealed both significant partial but equal mediators of hostility and dissociation. However, a portion of the direct effect between sexual assault and suicidal ideation remained unaccounted for by indirect effects. The current model supports previous work on dialectical behavior therapy that says either side of the dialectic between extreme expression and suppression of hostility increases the likelihood of suicidal thinking after sexual assault. With sexual assault survivors, practitioners should use strategies that emphasize both anger expression and healthy avoidance as a way to modulate emotion to potentially reduce suicidal thoughts. Future research should focus on different gender models, additional possible mediators such as alcohol use and guilt, and different forms of sexual assault. Limitations of the correlational, cross-sectional methodology are discussed.