Tutorial: The practical application of longitudinal structural equation mediation models in clinical trials

Parent-Child Interactions May Help to Explain Relations Between Parent Characteristics and Clinically Observed Child Autistic Behaviours

The importance of supporting parent-child interactions has been noted in the context of prodromal autism, but little consideration has been given to the possible contributing role of parental characteristics, such as psychological distress. This cross-sectional study tested models in which parent-child interaction variables mediated relations between parent characteristics and child autistic behaviour in a sample of families whose infant demonstrated early signs of autism (N = 103). The findings suggest that associations between parent characteristics (psychological distress; aloofness) and child autistic behaviours may be mediated by the child's inattentiveness or negative affect during interactions. These findings have important implications in developing and implementing interventions in infancy which target the synchrony of parent-child interaction with the goal to support children's social communication development.

Time-lagged panel models in psychotherapy process and mechanisms of change research: Methodological challenges and advances

In recent years, there has been increasing interest in utilizing time-lagged panel models to study mechanisms of change in psychotherapy. These models offer valuable insights into the dynamic relationships between variables over time and offer stronger causal inference capabilities than cross-sectional analyses. Therefore, they are well-suited for modeling the intricate relationships between mechanisms of change and outcomes in psychotherapy studies, which are typically beyond experimental control. However, their complexity, coupled with the fact that detailed explanations are often embedded in dense statistical or econometric texts, poses challenges. This paper provides a background on cross-lagged panel models and delves deeper into explaining the issues of 1) dynamic panel bias, 2) long-run effects, and 3) testing whether different treatments work by different mechanisms. Using data from a psychotherapy study on treatment of adolescent depression, I demonstrate how these issues manifest in real data. In conclusion, I recommend using structural equation modeling to circumvent dynamic panel bias, reporting long-run effects to reveal the long-term impact of sustained therapeutic work on mechanisms of change, and carefully considering whether mediation, moderation, or a combination of both, best describes differential effects of mechanisms between treatments.

Generalisation of Social Communication Skills by Autistic Children During Play-Based Assessments Across Home, School and an Unfamiliar Research Setting

We investigated autistic children's generalisation of social communication over time across three settings during a play-based assessment with different adults and explore the potential moderating effects on generalisation of age, nonverbal IQ and level of restricted and repetitive behaviours. The social communication abilities of 248 autistic children (2-11 years, 21% female, 22% single parent, 60% white) from three UK sites were assessed from 1984 video interactions in three contexts with three different interaction partners (parent/home, teaching assistant/school, researcher/clinic) at baseline, midpoint (+ 7m) and endpoint (+ 12m) within the Paediatric Autism Communication Trial-Generalised (PACT-G), a parent-mediated social communication intervention. Children's midpoint social communication at home generalised to school at midpoint and to clinic at endpoint. Generalisation was stronger from home to school and clinic than school to home and clinic. Generalisation was not moderated by age, nonverbal IQ or restricted and repetitive behaviour. Broader child development did not explain the pattern of results. The current study is the largest study to date to explore generalisation with autistic children and provides novel insight into their generalisation of social communication skills. Further research is needed to gain a more comprehensive understanding of facilitators of generalisation across settings and interaction partners in order to develop targeted strategies for interventions to enhance outcomes for young autistic children.

The Impact of Monetary Incentives on Delay Discounting Within a Year-Long Physical Activity Intervention

BACKGROUND

Delay discounting is the depreciation in a reward's perceived value as a function of the time until receipt. Monetary incentive programs that provide rewards contingent on meeting daily physical activity (PA) goals may change participants' delay discounting preferences.

PURPOSE

Determine if monetary incentives provided in close temporal proximity to meeting PA goals changed delay discounting, and if such changes mediated intervention effects.

METHODS

Inactive adults (n = 512) wore accelerometers during a 12-month intervention where they received proximal monetary incentives for meeting daily moderate-to-vigorous PA (MVPA) goals or delayed incentives for study participation. Delay discount rate and average MVPA were assessed at baseline, end of intervention, and a 24-month follow-up. Using structural equation modeling, we tested effects of proximal versus delayed rewards on delay discounting and whether any changes mediated intervention effects on MVPA. PA self-efficacy was also evaluated as a potential mediator, and both self-efficacy and delay discounting were assessed as potential moderators of intervention effects.

RESULTS

Proximal rewards significantly increased participants' delay discounting (β = 0.238, confidence interval [CI]: -0.078, 0.380), indicating greater sensitivity to reinforcement timing. This change did not mediate incentive-associated increases in MVPA at the end of the 12-month intervention (β = -0.016, CI: -0.053, 0.019) or at a 24-month follow-up (β = -0.020, CI: -0.059, 0.018). Moderation effects were not found.

CONCLUSIONS

Incentive-induced increases in delay discounting did not deleteriously impact MVPA. This finding may help assuage concerns about using monetary incentives for PA promotion, but further research regarding the consequences of changes in delay discounting is warranted.

Examining the role of living alone and loneliness in predicting health-related quality of life: results from the Healthy Aging Longitudinal Study in Taiwan (HALST)

PURPOSE

This study aimed to investigate the distinct yet interconnected aspects of social isolation, namely living alone and loneliness, and their individual and combined effects on predicting health-related quality of life (HRQoL).

METHODS

A comprehensive analysis, encompassing both cross-sectional and longitudinal approaches, was conducted using a nationally representative sample of 5644 community-dwelling adults aged 55 and older from the Healthy Aging Longitudinal Study in Taiwan (HALST).

RESULTS

Baseline data revealed that 9% of the sample reported living alone, while 10.3% reported experiencing loneliness, with 2.5% reporting both living alone and feeling lonely. Regression analyses consistently demonstrated that loneliness was significantly associated with concurrent and subsequent lower physical (PCS) and mental (MCS) component of HRQoL. Conversely, additional analyses indicated that living alone could indirectly exacerbate the adverse effects of loneliness or contribute to prolonged feelings of loneliness, subsequently predicting lower HRQoL after 3.2 year.

CONCLUSION

In terms of practical implications, interventions and policies aiming to enhance HRQoL in older adults should give particular attention to those who report feelings of loneliness, especially individuals living alone.

Understanding the Mechanisms of Cognitive Remediation on Recovery in People With Early Psychosis: A Mediation and Moderation Analysis

BACKGROUND

To provide precision cognitive remediation therapy (CR) for schizophrenia, we need to understand whether the mechanism for improved functioning is via cognition improvements. This mechanism has not been rigorously tested for potential moderator effects.

STUDY DESIGN

We used data (n = 377) from a randomized controlled trial using CIRCuiTS, a therapist-supported CR, with participants from first-episode psychosis services. We applied structured equation modeling to test whether: (1) CR hours explain the goal attainment functional outcome (GAS) at posttreatment, (2) global cognitive improvement mediates GAS, and if (3) total symptoms moderate the CR hours to cognitive improvement pathway, and/or negative symptoms moderate the cognition to functioning pathway, testing moderator effects via the mediator or directly on CR hours to functioning path.

STUDY RESULTS

CR produced significant functioning benefit for each therapy hour (Coeff = 0.203, 95% CI 0.101-0.304, P < .001). The mediated path from CR hours to cognition and cognition to functioning was small and nonsignificant (Coeff = 0.014, 95% CI = -0.010, 0.037, P = .256). Total symptoms did not moderate the path to cognition (P = .211) or the direct path to outcome (P = .896). However, negative symptoms significantly moderated the effect of cognitive improvements on functioning (P = .015) with high negative symptoms reducing the functional gains of improved cognition.

CONCLUSIONS

Although cognitive improvements were correlated with functioning benefit, they did not fully explain the positive effect of increased therapy hours on functioning, suggesting additional CR factors also contribute to therapy benefit. Negative symptoms interfere with the translation of cognitive improvements into functional gains so need consideration.

Mediation of 6-year mid-childhood follow-up outcomes after pre-school social communication (PACT) therapy for autistic children: randomised controlled trial

BACKGROUND

There are very few mechanistic studies of the long-term impact of psychosocial interventions in childhood. The parent-mediated Paediatric Autism Communication Therapy (PACT) RCT showed sustained effects on autistic child outcomes from pre-school to mid-childhood. We investigated the mechanism by which the PACT intervention achieved these effects.

METHODS

Of 152 children randomised to receive PACT or treatment as usual between 2 and 5 years of age, 121 (79.6%) were followed 5-6 years after the endpoint at a mean age of 10.5 years. Assessors, blind to the intervention group, measured Autism Diagnostic Observation Scale Calibrated Severity Score (ADOS CSS) for child autistic behaviours and Teacher Vineland (TVABS) for adaptive behaviour in school. Hypothesised mediators were child communication initiations with caregivers in a standard play observation (Dyadic Communication Measure for Autism, DCMA). Hypothesised moderators of mediation were baseline child non-verbal age equivalent scores (AE), communication and symbolic development (CSBS) and 'insistence on sameness' (IS). Structural equation modelling was used in a repeated measures mediation design.

RESULTS

Good model fits were obtained. The treatment effect on child dyadic initiation with the caregiver was sustained through the follow-up period. Increased child initiation at treatment midpoint mediated the majority (73%) of the treatment effect on follow-up ADOS CSS. A combination of partial mediation from midpoint child initiations and the direct effect of treatment also contributed to a near-significant total effect on follow-up TVABS. No moderation of this mediation was found for AE, CSBS or IS.

CONCLUSIONS

Early sustained increase in an autistic child's communication initiation with their caregiver is largely responsible for the long-term effects from PACT therapy on autistic and adaptive behaviour outcomes. This supports the theoretical logic model of PACT therapy but also illuminates fundamental causal processes of social and adaptive development in autism over time: early social engagement in autism can be improved and this can have long-term generalised outcome effects.

Within-Person Variability Score-Based Causal Inference: A Two-Step Estimation for Joint Effects of Time-Varying Treatments

Behavioral science researchers have shown strong interest in disaggregating within-person relations from between-person differences (stable traits) using longitudinal data. In this paper, we propose a method of within-person variability score-based causal inference for estimating joint effects of time-varying continuous treatments by controlling for stable traits of persons. After explaining the assumed data-generating process and providing formal definitions of stable trait factors, within-person variability scores, and joint effects of time-varying treatments at the within-person level, we introduce the proposed method, which consists of a two-step analysis. Within-person variability scores for each person, which are disaggregated from stable traits of that person, are first calculated using weights based on a best linear correlation preserving predictor through structural equation modeling (SEM). Causal parameters are then estimated via a potential outcome approach, either marginal structural models (MSMs) or structural nested mean models (SNMMs), using calculated within-person variability scores. Unlike the approach that relies entirely on SEM, the present method does not assume linearity for observed time-varying confounders at the within-person level. We emphasize the use of SNMMs with G-estimation because of its property of being doubly robust to model misspecifications in how observed time-varying confounders are functionally related to treatments/predictors and outcomes at the within-person level. Through simulation, we show that the proposed method can recover causal parameters well and that causal estimates might be severely biased if one does not properly account for stable traits. An empirical application using data regarding sleep habits and mental health status from the Tokyo Teen Cohort study is also provided.

Multiple imputation of missing data in multilevel ecological momentary assessments: an example using smoking cessation study data

Advances in digital technology have greatly increased the ease of collecting intensive longitudinal data (ILD) such as ecological momentary assessments (EMAs) in studies of behavior changes. Such data are typically multilevel (e.g., with repeated measures nested within individuals), and are inevitably characterized by some degrees of missingness. Previous studies have validated the utility of multiple imputation as a way to handle missing observations in ILD when the imputation model is properly specified to reflect time dependencies. In this study, we illustrate the importance of proper accommodation of multilevel ILD structures in performing multiple imputations, and compare the performance of a multilevel multiple imputation (multilevel MI) approach relative to other approaches that do not account for such structures in a Monte Carlo simulation study. Empirical EMA data from a tobacco cessation study are used to demonstrate the utility of the multilevel MI approach, and the implications of separating participant- and study-initiated EMAs in evaluating individuals' affective dynamics and urge.

Acceptance and Commitment Therapy Processes and Mediation: Challenges and How to Address Them

Acceptance and commitment therapy (ACT) emphasizes a focus on theory-driven processes and mediating variables, a laudable approach. The implementation of this approach would be advanced by addressing five challenges, including (a) distinguishing ACT processes in measurement contexts, (b) developing and rigorously validating measures of ACT processes, (c) the wide use of psychometrically weaker ACT process measures and the more limited use of stronger measures in earlier work, (d) the inconsistency of past evidence that ACT processes are sensitive or specific to ACT or mediate ACT outcomes specifically, and (e) improving statistical power and transparency. Drawing on the existing literature, we characterize and provide evidence for each of these challenges. We then offer detailed recommendations for how to address each challenge in ongoing and future work. Given ACT's core focus on theorized processes, improving the measurement and evaluation of these processes would significantly advance the field's understanding of ACT.

Alcohol use as a mediator of the effect of two alcohol reduction interventions on mental health symptoms of ART clients in Vietnam

We aimed to examine the mediating role of alcohol use in the pathway from the interventions to depression and anxiety symptoms using data from a randomized controlled trial among people living with HIV (PWH) with hazardous alcohol use (n = 440) in Thai Nguyen, Vietnam. Participants were randomized into either a combined intervention (CoI), a brief intervention (BI) and a standard of care arm. Both interventions were based on cognitive behavioral therapy and motivational enhancement therapy. Alcohol use was measured as the percentage of days abstinent from alcohol in the last 30 days. Symptoms of depression and anxiety were measured with the Patient Health Questionnaire-9 and Generalized Anxiety Disorder-7 scales. Alcohol use was a significant mediator of the effects of two alcohol interventions on depression symptoms, but not anxiety symptoms. There were significant indirect effects via alcohol use of both interventions on depression symptoms at 12 months (CoI: mean difference (MD) = -0.134; 95%CI: -0.251, -0.035); (BI: MD = -0.141; 95%CI: -0.261, -0.038). There were no significant direct or total effects of the interventions on either symptoms at 12 months. Interventions with a dual focus on mental health and alcohol disorders are needed to determine optimal ways to tackle these common comorbidities among PWH.

The effect of an adapted Mindfulness-Based Stress Reduction program on mental health, maternal bonding and birth outcomes in psychosocially vulnerable pregnant women: a study protocol for a randomized controlled trial in a Danish hospital-based outpatient setting

BACKGROUND

Stress and mental disorders in pregnancy can adversely affect the developing fetus. Women with a preconception history of mental disorders or of psychosocial vulnerabilities are at increased risk of experiencing perinatal stress or mental health problems. Mindfulness-Based-Stress-Reduction (MBSR) is an acceptable intervention for pregnant women and has a growing evidence-base with meta-analyses consistently pointing to reductions in symptoms of stress, anxiety and depression. This study protocol aim to address the need for a wider array of evidence-based and non-pharmacological options during pregnancy to reduce stress and improve mental health in a psychosocially highly vulnerable group of women.

METHODS

Pregnant women with a preconception history of mental disorders or psychosocial vulnerabilities (n = 240) will be recruited from an obstetric ambulatory clinic at Copenhagen University Hospital, Hvidovre, Denmark. Recruitment for the study began in March 2022 and will continue until the desired number of participants is reached. Consenting pregnant women will be randomized to one of two study arms, an adapted MBSR program as add on to usual care or usual care alone. The primary outcome is mental wellbeing at nine months post-randomization. Secondary and exploratory outcomes include stress, anxiety, depression, and maternal antenatal attachment, experience of childbirth, delivery and mode of delivery. Mindfulness and self-compassion are examined as possible mediators of the effect on outcomes.

DISCUSSION

Teaching the skills of mindfulness meditation to a psychosocially vulnerable group of pregnant women could prove a viable and non-pharmacological approach to improve mental health and wellbeing during pregnancy, reduce stress and support the transition to parenthood. Mindfulness-Based Stress Reduction does not target a particular group, and results from the study is thus of potential relevance for pregnant women in general as a means of reducing stress and improving perinatal mental health and wellbeing.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT05300646 . Registered March 29, 2022.

Self-care behaviors, drinking, and smoking to cope with psychological distress during COVID-19 among Chinese college students: the role of resilience

OBJECTIVE

College students are vulnerable to psychological distress during COVID-19 due to pandemic-related stressors. In response to psychological distress, college students engage in various coping behaviors, such as self-care behaviors and substance use. The transactional model of stress and coping depicts a cognitive appraisal process in the stress-coping association. Psychological resilience is an essential factor for the cognitive appraisal. This study aimed to investigate the mediation effects of resilience on psycho-behavioral health in response to COVID-19 stressors.

DESIGN

Longitudinal data were collected from 1,225 Chinese college students via web-based anonymous surveys at wave 1 (T1, between Jan 31 and Feb 11, 2020) and wave 2 (T2, between Mar 20 and Apr 3, 2020).

MAIN OUTCOME MEASURES

Participants reported their COVID-19 stressors (T1), resilience (T1), psychological distress (depression and anxiety; T2), and coping behaviors (self-care behaviors, drinking, and smoking; T2). Path analysis was used for data analyses.

RESULTS

Resilience mediated the association between COVID-19 stressors and psychological distress. Resilience together with psychological distress mediated the association of COVID-19 stressors with self-care behaviors or drinking.

CONCLUSIONS

Resilience appears to offer protection that promotes psycho-behavioral health in college students in the face of COVID-19 stressors. Interventions for college students should attend to resilience.

Treating sleep problems in young children: A randomised controlled trial of a group-based, parent-focused behavioural sleep intervention

This study tested the efficacy of a 5 × 1.5 h/session, group-based, parent-focused, behavioural intervention (BI) targeting sleep problems in preschool children. Parents were randomised to either the BI (N = 62) or care as usual (CAU; N = 66) conditions. Outcomes included sleep, anxiety, behavioural problems, internalising and externalising symptoms, transition to school and academic achievement. Assessments were conducted at pre- and post-BI intervention (in the year prior to formal schooling), and then at follow-ups 1 and 2 in the first year of formal schooling. Relative to the CAU, the BI condition demonstrated significantly greater improvements in sleep, anxiety, behaviour problems and internalising and externalising symptoms from pre-to post-intervention. Improvements in sleep, anxiety, and internalising symptoms were maintained, while behaviour and externalising symptoms were further improved upon at school follow-up 2. For the BI group, improvements in sleep at post-intervention were found to mediate improvements in anxiety, internalising, and externalising symptoms, but not behaviour problems, at school follow-ups 1 and 2. There were no significant effects of condition on school transition or academic outcome measures. The results suggest that the BI is effective for sleep, anxiety, behaviour, internalising and externalising symptoms, but not for school transition or academic outcomes. ANZCTR NUMBER: ACTRN12618001161213.

A randomized controlled trial of a preventive intervention for the children of parents with depression: mid-term effects, mediators and moderators

BACKGROUND

In a parallel randomized controlled trial the effectiveness of the family- and group-based cognitive-behavioural "Gug-Auf" intervention in preventing depression in children of depressed parents was evaluated. We hypothesized that the intervention would be associated with reduced incidence of depression at 15 months as well as with reduced symptom severity at 6, 9, and 15 months. We also explored the role of a number of mediators and moderators.

METHODS

Families were included if a parent (n = 100, mean age = 46.06, 61% female) had experienced depression and children (n = 135, aged 8-17 years, 53% female) had no mental illness. Families (91.5% German) were randomly allocated (50:50 block-wise; stratified by child age and parental depression) to the 12-session "GuG-Auf" intervention or no intervention. Outcomes were assessed (on an intention-to-treat basis) at 0-(T1), 6-(T2), 9-(T3) and 15-months (T4) after baseline. Primary outcome (onset of depression; T4) was assessed with standardized (blinded) clinical interviews. Secondary (unblinded) outcome was risk of depression (at T2-T4) indicated by self- and parent-reported symptoms of internalizing, externalizing and depressive disorder. Potential mediators were emotion regulation, attributional style, knowledge of depression and parenting style. Potential moderators were parental depression severity and negative life events.

RESULTS

None of the children who received the intervention developed depression, whereas two of those in the control group did. The intervention significantly reduced depression risk (indicated by severity of self-reported internalizing symptoms) at T3 (p = .027, d = -0.45) and T4 (p = .035, d = -0.44). Both groups showed reduced depressive symptoms (p = .029, d = -0.44). Cognitive problem-solving and negative parenting emerged as mediators. There was no evidence that the intervention was associated with parent-reported internalizing symptoms or externalizing symptoms. No adverse events were observed.

CONCLUSIONS

Children of parents with depression showed an increase in self-reported (but not parent-reported) internalizing symptoms over time. This increase was not present in children who received the GuG-Auf intervention. The intervention was not associated with changes in externalizing symptoms. Conclusions regarding prevention of the onset of depression were not possible. Despite some limitations in the generalizability, these findings contribute to reducing the burden of youth depression.

REGISTRATION

The trial was registered on 16/04/2014 at ClinicalTrials.gov ( NCT02115880 ) and study protocol published in BMC Psychiatry ( https://bmcpsychiatry.biomedcentral.com/articles/10.1186/s12888-014-0263-2 ).

Altered self-reported resting state mediates the effects of Mindfulness-Based Stress Reduction on mental health: a longitudinal path model analysis within a community-based randomized trial with 6-months follow-up

Background

A large body of randomized controlled trials (RCTs) has shown that mindfulness-based interventions are effective for improving mental health, but research is lacking in regards to the mechanisms of change. We aimed to investigate the mediating effects of self-reported altered resting state of Mindfulness-Based Stress Reduction (MBSR) on mental health, when provided as a universal intervention in a real-life context.

Methods

Autoregressive path models with three time points of measurement, and contemporaneous and constant b paths were used in an RCT. The RCT took place in all five geographical regions of Denmark and included 110 schools and 191 schoolteachers. The schools were randomized 1:1 in each geographical region to intervention or a wait-list control group. The intervention was the standardized MBSR. Data were collected at baseline and after 3 and 6  months. The outcomes were perceived stress, measured by Cohen's Perceived Stress Scale (PSS), symptoms of anxiety and depression, measured by Hopkins Symptom Check List-5 (SCL-5), and well-being measured by WHO-5 Well-being Index (WHO-5). The mediator was resting state measured by the Amsterdam Resting State Questionnaire (ARSQ).

Results

Statistically significant mediated effects of altered ARSQ-subscales scores for Discontinuity of Mind, Planning, and Comfort were found for the MBSR effect on all outcomes; PSS, SCL-5 and WHO-5. Furthermore, statistically significant mediated effects of altered sleepiness subscale score of the effects on PSS and SCL-5 of MBSR were found. No statistically significant mediating effects of the subscales Theory of Mind, Self and Somatic Awareness for the MBSR intervention effect were found.

Conclusion

The results support that the MBSR program can alter self-reported resting state, towards less mind wandering and more comfort, measured by the ARSQ, and that this may explain some of the mechanisms regarding the effectiveness of MBSR on mental health at 6 months, when provided as a universal intervention. The study provides insight into an active ingredient of how MBSR may improve mental health and well-being. It supports the suggestions that mindfulness meditation may be a sustainable way of training the mental health.Clinical trial registration:ClinicalTrials.gov, identifier NCT03886363.

The impact of omitting confounders in parallel process latent growth curve mediation models: Three sensitivity analysis approaches

Parallel process latent growth curve mediation models (PP-LGCMMs) are frequently used to longitudinally investigate the mediation effects of treatment on the level and change of outcome through the level and change of mediator. An important but often violated assumption in empirical PP-LGCMM analysis is the absence of omitted confounders of the relationships among treatment, mediator, and outcome. In this study, we analytically examined how omitting pretreatment confounders impacts the inference of mediation from the PP-LGCMM. Using the analytical results, we developed three sensitivity analysis approaches for the PP-LGCMM, including the frequentist, Bayesian, and Monte Carlo approaches. The three approaches help investigate different questions regarding the robustness of mediation results from the PP-LGCMM, and handle the uncertainty in the sensitivity parameters differently. Applications of the three sensitivity analyses are illustrated using a real-data example. A user-friendly Shiny web application is developed to conduct the sensitivity analyses.

Internet-delivered treatment for patients suffering from severe functional somatic disorders: Protocol for a randomized controlled trial

Background

Functional somatic disorders (FSDs) with symptoms from multiple organs, i.e., multi-system type, are common in the general population and may lead to disability and reduced quality of life. Evidence for efficient treatment programs has been established, however, there is a need for making treatments accessible to a larger group of patients. Internet-delivered therapy has become prevalent and has proven as effective as face-to-face therapy, while providing a flexible and easily accessible treatment alternative. The aim of the current study is to compare the efficacy of the therapist-assisted internet-delivered treatment program One step at a time (OneStep) with the internet-delivered self-help program Get started (GetStarted).

Methods

A total of 166 participants aged 18-60 years diagnosed with multi-system FSD will be assessed and randomized to either 1) OneStep: a 14-week program consisting of 11 treatment modules based on principles from cognitive behavioural therapy or 2) GetStarted consisting of 1 module on psychoeducation. The primary outcome is physical health, assessed by a Short Form Health Survey (SF-36) aggregate score of the subscales vitality, physical functioning, and bodily pain 3 months after end-of-treatment and self-reported improvement assessed by the Clinical Global Improvement Scale. Secondary outcomes include symptom load, depression, anxiety, and illness worry. Process measures include emotional distress, illness perception, illness behaviour, and symptom interference.

Conclusions

This study is the first study to test an internet-delivered treatment program for FSD, multi-system type and has the potential to show the importance of making evidence-based internet-delivered treatment for FSD more accessible.

Conceptualizing and Examining Change in Communication Research

Communication research often focuses on processes of communication, such as how messages impact individuals over time or how interpersonal relationships develop and change. Despite their importance, these change processes are often implicit in much theoretical and empirical work in communication. Intensive longitudinal data are becoming increasingly feasible to collect and, when coupled with appropriate analytic frameworks, enable researchers to better explore and articulate the types of change underlying communication processes. To facilitate the study of change processes, we (a) describe advances in data collection and analytic methods that allow researchers to articulate complex change processes of phenomena in communication research, (b) provide an overview of change processes and how they may be captured with intensive longitudinal methods, and (c) discuss considerations of capturing change when designing and implementing studies. We are excited about the future of studying processes of change in communication research, and we look forward to the iterations between empirical tests and theory revision that will occur as researchers delve into studying change within communication processes.

Time lags and time interactions in mixed effects models impacted longitudinal mediation effect estimates

OBJECTIVES

Longitudinal mediation effects can be estimated with mixed effects models. Mixed effects models are versatile, as they accommodate the estimation of contemporaneous, lagged, time-independent, and time-dependent effects. However, the inclusion of time lags and time interactions in mixed effects models for longitudinal mediation analysis has received little attention. This article demonstrates how time lags and time interactions in mixed effects models affect the interpretation of longitudinal mediation effect estimates.

STUDY DESIGN AND SETTING

We used a data example from the Amsterdam Growth and Health Longitudinal Study to illustrate how the inclusion of time lags and time interactions in mixed effects models may affect the size and interpretation of longitudinal mediation effect estimates.

RESULTS

The chosen time lags between the determinant, mediator, and outcome influenced the size and interpretation of the mediation effect estimates. Furthermore, time interactions can be used to model linear or nonlinear development of the mediation effects over time.

CONCLUSION

The inclusion of time lags and time interactions should be considered when estimating longitudinal mediation effects based on mixed effects models, as this enables the estimation of lagged and time-dependent effects.

The Effect of Neuroepo on Cognition in Parkinson's Disease Patients Is Mediated by Electroencephalogram Source Activity

We report on the quantitative electroencephalogram (qEEG) and cognitive effects of Neuroepo in Parkinson's disease (PD) from a double-blind safety trial (https://clinicaltrials.gov/, number NCT04110678). Neuroepo is a new erythropoietin (EPO) formulation with a low sialic acid content with satisfactory results in animal models and tolerance in healthy participants and PD patients. In this study, 26 PD patients were assigned randomly to Neuroepo (n = 15) or placebo (n = 11) groups to test the tolerance of the drug. Outcome variables were neuropsychological tests and resting-state source qEEG at baseline and 6 months after administering the drug. Probabilistic Canonical Correlation Analysis was used to extract latent variables for the cognitive and for qEEG variables that shared a common source of variance. We obtained canonical variates for Cognition and qEEG with a correlation of 0.97. Linear Mixed Model analysis showed significant positive dependence of the canonical variate cognition on the dose and the confounder educational level (p = 0.003 and p = 0.02, respectively). Additionally, in the mediation equation, we found a positive dependence of Cognition with qEEG for (p = < 0.0001) and with dose (p = 0.006). Despite the small sample, both tests were powered over 89%. A combined mediation model showed that 66% of the total effect of the cognitive improvement was mediated by qEEG (p = 0.0001), with the remaining direct effect between dose and Cognition (p = 0.002), due to other causes. These results suggest that Neuroepo has a positive influence on Cognition in PD patients and that a large portion of this effect is mediated by brain mechanisms reflected in qEEG.

lcsm: An R package and tutorial on latent change score modelling

Latent change score models (LCSMs) are used across disciplines in behavioural sciences to study how constructs change over time. LCSMs can be used to estimate the trajectory of one construct (univariate) and allow the investigation of how changes between two constructs (bivariate) are associated with each other over time. This paper introduces the R package lcsm, a tool that aims to help users understand, analyse, and visualise different latent change score models. The lcsm package provides functions to generate model syntax for basic univariate and bivariate latent change score models with different model specifications. It is also possible to visualise different model specifications in simplified path diagrams. An interactive application illustrates the main functions of the package and demonstrates how the model syntax and path diagrams change based on different model specifications. This R package aims to increase the transparency of reporting analyses and to provide an additional resource to learn latent change score modelling.

Safety aid elimination as a brief, preventative intervention for social anxiety: A randomized controlled trial in university students

Although there are a variety of treatment options for social anxiety, effective prevention strategies for those with subclinical social anxiety are limited. This study evaluated a single session group formatted prevention program focused on the reduction of safety behaviors in both a proof-of-concept study and a randomized controlled trial (RCT). Participants (N = 59) were nontreatment seeking Japanese university students with high levels of social anxiety. Participants were randomized to either an active treatment focused on identification and elimination of safety behavior or a control group involving the discussion of healthy coping strategies. Both conditions met for 120 min in small groups (4 to 6 participants per group). The preliminary proof-of-concept study as well as the RCT demonstrated high levels of acceptability. Findings from the RCT indicated significant improvement in social anxiety symptoms among those in the active treatment condition at post-treatment, which was maintained at follow-up. In addition, participants in the treatment condition showed significant improvement in levels of depression. The effect size difference in symptoms between conditions was in the large range. The present study provides preliminary support for the efficacy of a newly developed treatment program targeting safety behaviors in students with subclinical social anxiety. The current results also illustrate the promise of a brief, indicated prevention strategy focused on safety behavior among those with subclinical social anxiety.

Is patient activation a mediator of the effect of a health promoting intervention in adults at high risk of type 2 diabetes? A longitudinal path model analysis within a randomised trial

Background

Exploring mediators of preventive intervention effects has important implications for the planning of complex interventions. Our aim was to assess the extent to which knowledge, skills and confidence to manage health, here measured as “patient activation”, was a mediator of the effect of the intervention “Live your life without diabetes” on weight, waist circumference and systolic blood pressure at 12 months follow-up in adults at high risk of type 2 diabetes.

Methods

Autoregressive path models with three time points of measurement, and contemporaneous and constant b paths were used in a randomised controlled trial (RCT). The RCT took place in a Danish municipal healthcare center and included 127 individuals aged 28 to 70 years with fasting plasma glucose: 6.1–6.9 mmol/l and/or glycated haemoglobin (HbA_1c): 42.0–47.9 mmol/mol. Participants were randomised to routine care (n = 64), or intervention (n = 63). The intervention group received an empirical and theory-based intervention delivered over four two-h group sessions during five weeks, and two further sessions after one and six months. The outcomes were weight, waist circumference and systolic blood pressure, and the mediator was patient activation, measured by the self-reported Patient Activation Measure (PAM). Data for the present study was derived from questionnaires and clinical measures from baseline, three- and 12-months follow-up.

Results

Mediated effects via PAM on: weight: − 0.09 kg (95% CI − 0.38 to 0.20) out of the total effect − 1.09 kg (95% CI − 3.05 to 0.87); waist circumference: − 0.04 cm (95% CI − 0.36 to 0.28) out of the total effect − 1.86 cm (95% CI − 4.10 to 0.39); and systolic blood pressure: − 0.31 mmHg (− 1.10 to 0.49) out of the total effect − 2.73 mmHg (95% CI − 6.34 to 0.87).

Conclusion

We found no mediating effects of patient activation as a single variable of the intervention “Live your life without diabetes” on weight, waist circumference and systolic blood pressure at 12 months follow-up in adults at high risk of type 2 diabetes. Our study demonstrates an analytic approach for estimating mediating effects in complex interventions that comply with the criteria on temporal ordered data. Future studies should include possible interacting variables.

Dynamic change meets mechanisms of change: Examining mediators in the latent change score framework

Researchers in behavioral sciences are often interested in longitudinal behavior change outcomes and the mechanisms that influence changes in these outcomes over time. The statistical models that are typically implemented to address these research questions do not allow for investigation of mechanisms of dynamic change over time. However, latent change score models allow for dynamic change (not just linear or exponential change) over time and have flexibility in parameter constraints that other longitudinal models do not have. Developmental researchers also frequently utilize mediation analyses to investigate mechanisms of influence in longitudinal research implemented in path analytic or latent growth curve models. In this article, we provide three examples of how mediation can be tested in the latent change score framework by combining aspects of traditional mediation models with latent change score models of repeated measures outcomes (and mediators and predictors) with more than two timepoints. We also provide the Mplus syntax to complete these analyses and practical considerations of latent change score mediation (LCSM) models.

Temporal Associations between Depression and Hostility in the Context of a Divorce Intervention

Divorce interventions have been found effective in reducing negative outcomes for newly divorced people, including depression and hostility. Typically, divorce interventions cover a variety of issues that may influence people's level of depression and hostility. However, it is unclear whether the interventions differentially affect the outcomes. That is, it may be that intervention participation leads to a reduction in depression, which is associated with a prospective reduction in hostility - or vice versa. The current study used a sample of 1,856 recently divorced Danes, who completed questionnaires at baseline, 3-, 6-, and 12-month post-divorce. Structural equation modeling revealed that while depression and hostility were concurrently associated, there were no prospective associations, except for baseline depression predicting 3-month hostility. Moreover, the associations did not differ by gender. The results suggest that the intervention content may have influenced both depression and hostility. These findings may be useful in guiding future divorce intervention developments.

COVID-19-related stressful experiences and posttraumatic stress disorder symptoms among college students in China: A moderated mediation model of perceived control over the future and empathy

The current study aims to investigate the mediating effect of perceived control over the future and the moderating effect of empathy on the association between stressful experiences and PTSD symptoms among college students in China in response to COVID-19. A sample of 1,225 college students (70.69% were female, M age = 20.22 years, SD = 2.02) were recruited using web-based surveys at wave 1 (W1) and wave 2 (W2) longitudinally. Results showed that COVID-19-related stressful experiences were significantly associated with PTSD symptoms. Perceived control over the future partially mediated the relationship between these two variables ( indirect effect size = 0.09, p < 0.01). Empathy significantly moderated the path from perceived control over the future to PTSD symptoms, suggesting that the association was stronger for individuals with higher levels of empathy. Findings suggest a protective effect of perceived control over the future on college students’ PTSD symptoms during the COVID-19 pandemic. Such a protective effect was intensified by empathy. Future intervention to manage PTSD symptoms should be tailored to positive future expectations and empathy.

The Effects of a Mindfulness Program on Mental Health in Students at an Undergraduate Program for Teacher Education: A Randomized Controlled Trial in Real-Life

Background: In this study, we aimed to investigate the effects of a mindfulness program including Mindfulness-Based Stress Reduction (MBSR) on the mental health of student teachers when offered at their educational institution in a real-life context.

Methods: A parallel randomized controlled trial (RCT) was conducted among self-selected student teachers at a Danish undergraduate program for teacher education in the autumns of 2019 and 2020. Participation was not recommended in case of (1) clinical depression or a diagnosis of psychosis or schizophrenia, (2) abuse of alcohol, drugs, and/or medicine. Randomization was performed by a Statistician who was blinded to the identity of the students. Data was collected using self-reported questionnaires. The primary outcome was a change in perceived stress 3 months from baseline. Secondary outcome measures were symptoms of anxiety and depression, well-being, resilience, mindfulness, and thoughts and feelings during rest. The effects were analyzed according to the intention-to-treat principle using mixed-effect linear regression models. Mediating effects of mindfulness skills on the mental health outcomes were explored using structural equation modeling.

Results: The study group included 67 student teachers with 34 allocated to the intervention group (median age: 25 years; women: n = 24, 71%); and 33 students (median age: 25 years; women: n = 25, 76%) allocated to a waiting list control group. At baseline, mean Perceived Stress Scale (PSS) scores were 18.88 (SD: 5.75) in the intervention group and 17.91 (SD: 6.36) in the waiting list control group. A total of 56 students completed the questionnaire at a 3-month follow-up (28 in both the intervention- and the control group). Statistically significant effects of the intervention were found on perceived stress, symptoms of anxiety and depression, well-being, and on three of seven resting-state dimensions. No effects were found on resilience or mindfulness. Statistically significant mediated effects via resting-state dimensions were found.

Conclusion The findings suggested that offering a mindfulness program at an undergraduate program for teacher education could significantly improve the mental health among self-selected students within 3 months. Results of mediation analysis supported the hypothesis that some of the effects might be explained by reduced distracting thoughts.

Clinical Trial Registration: [www.ClinicalTrials.gov], identifier [NCT04558099].

The role of mindfulness and relaxation in improved sleep quality following a mind-body and activity program for chronic pain

Objectives

Poor sleep quality is prevalent among individuals with chronic pain and contributes to increased physical and emotional dysfunction. However, treatments that improve sleep quality among individuals with chronic pain are scant. A previously developed mind-body activity program for chronic pain has been shown to be feasible and associated with improvements in pain and physical and emotional function. Using secondary data-analysis, the purpose of this study was to understand whether participants also experienced significant and sustained improvements in sleep quality over time and whether these improvements were explained by change in two core treatment targets, relaxation and mindfulness.

Methods

Participants with heterogenous chronic pain (N = 82) were randomized to a mind-body activity intervention with (GetActive-Fitbit; n=41) or without (GetActive; n=41) a Fitbit device. Sleep quality was measured with the PSQI, mindfulness with the CAMS-R, and relaxation with the relaxation subscale of the MOCS-A. Mediation was tested via mixed-models analysis.

Results

Both intervention groups experienced significant and comparable improvements in sleep quality from baseline to post-treatment, which were sustained through a 3-month follow-up. Mindfulness and relaxation also improved significantly over time and these improvements were associated with improved sleep quality. Mindfulness and relaxation fully mediated improvement in sleep quality (medium to large effect sizes).

Conclusions

Results suggest that, despite not targeting sleep explicitly, the two mind-body activity programs hold promise for sustainably improving sleep quality among patients with chronic pain. Targeting mindfulness and relaxation may facilitate these improvements.

Mediation of outcomes for cognitive behavioral therapy targeted to parents of children with Functional Abdominal Pain Disorders

OBJECTIVE

There is a large body of evidence for the efficacy of Cognitive Behavioral Therapy (CBT) in treating Functional Abdominal Pain Disorders (FAPD) in children. In most CBT interventions for FAPD, parents participate together with their children. However, only one study to date has examined targeting parents alone for treatment. The aim of the current study was to examine mediators of a parent-only CBT treatment incorporating social learning (SLCBT) for FAPD in children.

METHODS

We examined mediators of child outcomes in an existing randomized controlled trial (n = 316) of parent-only social learning CBT compared to an education condition. Hypothesized mediators (parental protectiveness, perceived threat of pain, catastrophizing) were assessed at 3 months post-treatment, and outcomes (parent ratings of disability, quality of life, school absences, and health care visits) were assessed at 6 months post-treatment. Mediation analyses were performed using Hayes' PROCESS macro.

RESULTS

Pain catastrophizing significantly mediated treatment effects for all outcomes (B ranged from -1.65 to 2.22). Reduction in pain threat was a significant mediator for all outcomes (B ranged from -1.84 to 3.13) except school absences and health care visits. Decrease in parental protectiveness mediated effects on disability and missed school (B ranged from -1.47 to 1.34). Mediation effects did not differ by in-person or remote delivery of SLCBT.

CONCLUSION

Changes in maladaptive parental thoughts and behaviors following parent-only SLCBT intervention appeared to mediate the effects of the intervention. Parental catastrophizing appears to be a particularly important target given that decreases in that variable mediated all outcomes.

Efficacy and cost-effectiveness of a Transdiagnostic group-based exercise intervention: study protocol for a pragmatic multi-site randomized controlled trial

BACKGROUND

Mental disorders are prevalent and cause considerable burden of disease. Exercise has been shown to be efficacious to treat major depressive disorders, insomnia, panic disorder with and without agoraphobia and post traumatic stress disorder (PTSD).

METHODS

This pragmatic, two arm, multi-site randomised controlled trial will evaluate the efficacy and cost-effectiveness of the manualized, group-based six-months exercise intervention "ImPuls", among physically inactive patients with major depressive disorders, insomnia, panic disorder, agoraphobia and PTSD within a naturalistic outpatient context in Germany. A minimum of 375 eligible outpatients from 10 different study sites will be block-randomized to either ImPuls in addition to treatment as usual (TAU) or TAU only. ImPuls will be conducted by trained exercise therapists and delivered in groups of six patients. The program will combine (a) moderate to vigorous aerobic exercise carried out two-three times a week for at least 30 min with (b) behavior change techniques for sustained exercise behavior change. All outcomes will be assessed pre-treatment, post-treatment (six months after randomization) and at follow-up (12 months after randomization). Primary outcome will be self-reported global symptom severity assessed with the Brief Symptom Inventory (BSI-18). Secondary outcomes will be accelerometry-based moderate to vigorous physical activity, self-reported exercise, disorder-specific symptoms, quality-adjusted life years (QALY) and healthcare costs. Intention-to-treat analyses will be conducted using mixed models. Cost-effectiveness and cost-utility analysis will be conducted using incremental cost-effectiveness and cost-utility ratios.

DISCUSSION

Despite its promising therapeutic effects, exercise programs are currently not provided within the outpatient mental health care system in Germany. This trial will inform service providers and policy makers about the efficacy and cost-effectiveness of the group-based exercise intervention ImPuls within a naturalistic outpatient health care setting. Group-based exercise interventions might provide an option to close the treatment gap within outpatient mental health care settings.

TRIAL REGISTRATION

The study was registered in the German Clinical Trials Register (ID: DRKS00024152 , 05/02/2021).

Discernment of mediator and outcome measurement in the PACE trial

OBJECTIVE

When measuring latent traits, such as those used in psychology and psychiatry, it can be unclear whether the instruments used are measuring different concepts. This issue is particularly important in the context of mediation analysis, since for a sound mediation hypothesis the mediator and outcome should be distinct. We sought to assess the extent of measurement overlap between cognitive and behavioural mediators and physical functioning and fatigue outcomes in a large trial of treatments for chronic fatigue syndrome.

METHODS

A secondary analysis of 640 participants in the "Pacing, graded Activity, and Cognitive behaviour therapy" trial was conducted. Potential measurement overlap was assessed using generalised linear latent variable models where confirmatory factor models quantified the extent to which the addition of cross-loading items significantly improved model fit.

RESULTS

We considered 13 mediators and two outcomes, giving a total of 26 mediator-outcome pairs. Of these, only six showed evidence of cross-loading items, supporting the suggestion that the chosen mediator and outcome constructs were conceptually distinct.

CONCLUSION

This study highlights how established psychometric methods can be applied to assess measurement overlap in mediation analyses. We found minimal overlap between cognitive and behavioural mediators and physical functioning and fatigue outcomes that are often used in studies of chronic fatigue syndrome. The use of such methods in mediational studies where questionnaires are used to quantify latent traits would add to their robustness and transparency.

Change in negative attention bias mediates the association between attention bias modification training and depression symptom improvement

OBJECTIVE

Attention bias modification training (ABMT) is purported to reduce depression by targeting and modifying an attentional bias for sadness-related stimuli. However, few tests of this hypothesis have been completed.

METHOD

The present study examined whether change in attentional bias mediated a previously reported association between ABMT condition (active ABMT, sham ABMT, assessments only; N = 145) and depression symptom change among depressed adults. The preregistered, primary measure of attention bias was a discretized eye-tracking metric that quantified the proportion of trials where gaze time was greater for sad stimuli than neutral stimuli.

RESULTS

Contemporaneous longitudinal simplex mediation indicated that change in attentional bias early in treatment partially mediated the effect of ABMT on depression symptoms. Specificity analyses indicated that in contrast to the eye-tracking mediator, reaction time assessments of attentional bias for sad stimuli (mean bias and trial level variability) and lapses in sustained attention did not mediate the association between ABMT and depression change. Results also suggested that mediation effects were limited to a degree by suboptimal measurement of attentional bias for sad stimuli.

CONCLUSION

When effective, ABMT may improve depression in part by reducing an attentional bias for sad stimuli, particularly early on during ABMT. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

Explaining the Efficacy of an Internet-Based Behavioral Activation Intervention for Major Depression: A Mechanistic Study of a Randomized-Controlled Trial

Background

Behavioral activation is an effective treatment for depression that is theorized to facilitate structured increases in enjoyable activities that increase opportunities for contact with positive reinforcement; to date, however, only few mechanistic studies focused on a standalone intervention.

Method

Interventions using internet-based behavioral activation or psychoeducation were compared based on data from a randomized-controlled trial of 313 patients with major depressive disorder. Activation level and depression were measured fortnightly (baseline, Weeks 2, 4, 6, 8, 10), using the Patient Health Questionnaire-9 and the Behavioral Activation for Depression Scale-Short Form, respectively. Analysis was performed to determine if a change in activation level mediated treatment efficacy.

Results

Latent growth modeling showed that internet-based behavioral activation treatment significantly reduced depressive symptoms from baseline to the end of treatment (standardized coefficient = -.13, p = .017) by increasing the rate of growth in the activation level (mediated effect estimate = -.17, 95% CI [-.27, -.07]. Results from mixed effects and simplex models showed that it took 4 weeks before mediation occurred (i.e., a significant change in activation that led to a reduction in depressive symptoms).

Conclusion

Activation level likely mediated the therapeutic effect of behavioral activation on depression in our intervention. This finding may be of significant value to clinicians and depressed individuals who should anticipate a 4-week window before seeing a prominent change in activation level and a 6-week window before depressive symptomatology reduces. Future research must consolidate our findings on how behavioral activation works and when mediation occurs.

Endostatin as a Mediator Between Endothelial Function and Cognitive Performance in Those at Risk for Vascular Cognitive Impairment

Background:

Patients with coronary artery disease have an increased risk for developing vascular cognitive impairment. Endothelial function is often diminished and has been associated with lower cognitive performance in these patients. The link between endothelial function and cognition in coronary artery disease is not fully understood. Angiogenesis may play a role in mediating the association between endothelial function and cognition since angiogenic processes rely heavily on the endothelium.

Objective:

The aim of this study was to determine if markers of angiogenesis mediate the relationship between endothelial function and cognition in coronary artery disease patients.

Methods:

In 50 participants with coronary artery disease, endothelial function was assessed using peripheral arterial tonometry. Vascular endothelial growth factor (pro-angiogenic) and endostatin (anti-angiogenic) were measured in peripheral serum samples. Cognition was assessed using the Montreal Cognitive Assessment. A mediation analysis, using a bias corrected inferential bootstrapping method with 10,000 permutations, was used to determine if vascular endothelial growth factor or endostatin mediated an association between peripheral arterial tonometry measures and cognitive performance on the Montreal Cognitive Assessment.

Results:

Endostatin, but not vascular endothelial growth factor, mediated a relationship between endothelial function and cognitive performance when controlling for total years of education, body mass index, coronary artery bypass graft, stent, diabetes, and diuretic use. This analysis was also significant when delayed recall was substituted for the overall score on the Montreal Cognitive Assessment.

Conclusion:

These results suggest that endostatin mediates an association between endothelial function and cognitive performance in coronary artery disease.

Understanding Between-Person Interventions With Time-Intensive Longitudinal Outcome Data: Longitudinal Mediation Analyses

BACKGROUND

Mediation analysis is an important tool for understanding the processes through which interventions affect health outcomes over time. Typically the temporal intervals between X, M, and Y are fixed by design, and little focus is given to the temporal dynamics of the processes.

PURPOSE

In this article, we aim to highlight the importance of considering the timing of the causal effects of a between-person intervention X, on M and Y, resulting in a deeper understanding of mediation.

METHODS

We provide a framework for examining the impact of a between-person intervention X on M and Y over time when M and Y are measured repeatedly. Five conceptual and analytic steps involve visualizing the effects of the intervention on Y, M, the relationship of M and Y, and the mediating process over time and selecting an appropriate analytic model.

RESULTS

We demonstrate how these steps can be applied to two empirical examples of health behavior change interventions. We show that the patterns of longitudinal mediation can be fit with versions of longitudinal multilevel structural equation models that represent how the magnitude of direct and indirect effects vary over time.

CONCLUSIONS

We urge researchers and methodologists to pay more attention to temporal dynamics in the causal analysis of interventions.

Mendelian randomisation for mediation analysis: current methods and challenges for implementation

Mediation analysis seeks to explain the pathway(s) through which an exposure affects an outcome. Traditional, non-instrumental variable methods for mediation analysis experience a number of methodological difficulties, including bias due to confounding between an exposure, mediator and outcome and measurement error. Mendelian randomisation (MR) can be used to improve causal inference for mediation analysis. We describe two approaches that can be used for estimating mediation analysis with MR: multivariable MR (MVMR) and two-step MR. We outline the approaches and provide code to demonstrate how they can be used in mediation analysis. We review issues that can affect analyses, including confounding, measurement error, weak instrument bias, interactions between exposures and mediators and analysis of multiple mediators. Description of the methods is supplemented by simulated and real data examples. Although MR relies on large sample sizes and strong assumptions, such as having strong instruments and no horizontally pleiotropic pathways, our simulations demonstrate that these methods are unaffected by confounders of the exposure or mediator and the outcome and non-differential measurement error of the exposure or mediator. Both MVMR and two-step MR can be implemented in both individual-level MR and summary data MR. MR mediation methods require different assumptions to be made, compared with non-instrumental variable mediation methods. Where these assumptions are more plausible, MR can be used to improve causal inference in mediation analysis.

Mediators of the Disparities in Depression Between Sexual Minority and Heterosexual Individuals: A Systematic Review

Evidence suggests that sexual minorities (e.g., those identifying as lesbian, gay, or bisexual) experience increased rates of depression compared to heterosexual individuals. Minority stress theory suggests that this disparity is due to stigma experienced by sexual minorities. Stigma processes are proposed to contribute to reduced coping/support resources and increased vulnerability processes for mental health problems. This review provided a systematic examination of research assessing the evidence for mediating factors that help explain such disparities. A literature search was conducted using the databases PubMed, PsycINFO, and Web of Science. The review included 40 identified studies that examined mediators of sexual minority status and depressive outcomes using a between-group design (i.e., heterosexual versus sexual minority participants). Studies of adolescents and adult samples were both included. The most common findings were consistent with the suggestion that stressors such as victimization, harassment, abuse, and increased stress, as well as lower social and family support, may contribute to differing depression rates in sexual minority compared to heterosexual individuals. Differences in psychological processes such as self-esteem and rumination may also play a role but have had insufficient research attention so far. However, caution is needed because many papers had important methodological shortcomings such as the use of cross-sectional designs, inferior statistical analyses for mediation, or measures that had not been properly validated. Although firm conclusions cannot be drawn, the current evidence base highlights many factors potentially suitable for further exploration in high-quality longitudinal research or randomized studies intervening with the potential mediators.

Mind-Body Activity Program for Chronic Pain: Exploring Mechanisms of Improvement in Patient-Reported, Performance-Based and Ambulatory Physical Function

BACKGROUND

Improving physical function among patients with chronic pain is critical for reducing disability and healthcare costs. However, mechanisms underlying improvement in patient-reported, performance-based, and ambulatory physical function in chronic pain remain poorly understood.

PURPOSE

To explore psychosocial mediators of improvement in patient-reported, performance-based, and objective/accelerometer-measured physical function among participants in a mind-body activity program.

METHODS

Individuals with chronic pain were randomized to one of two identical 10-week mind-body activity interventions aimed at improving physical function with (GetActive-Fitbit; N=41) or without (GetActive; N=41) a Fitbit device. They completed self-reported (WHODAS 2.0), performance-based (6-minute walk test), and objective (accelerometer-measured step-count) measures of physical function, as well as measures of kinesiophobia (Tampa Kinesiophobia Scale), mindfulness (CAMS-R), and pain resilience (Pain Resilience Scale) before and after the intervention. We conducted secondary data analyses to test mediation via mixed-effects modeline.

RESULTS

Improvements in patient-reported physical function were fully and uniquely mediated by kinesiophobia (Completely Standardized Indirect Effect (CSIE)=.18; CI=0.08, 0.30; medium-large effect size), mindfulness (CSIE=-.14; CI=-25, -.05; medium effect size) and pain resilience (CSIE=-.07; CI=-.16, -.005; small-medium effect size). Improvements in performance-based physical function were mediated only by kinesiophobia (CSIE=-.11; CI=-23, -.008; medium effect size). No measures mediated improvements in objective (accelerometer measured) physical function.

CONCLUSION

Interventions aiming to improve patient-reported physical function in patients with chronic pain may benefit from skills that target kinesiophobia, mindfulness, and pain resilience, while those focused on improving performance-based physical function should target primarily kinesiophobia. More research is needed to understand mechanisms of improvement in objective, accelerometer-measured physical function.

TRIAL REGISTRATION

ClinicalTrials.gov NCT03412916.

Mediators for the Effect of Compassion Cultivating Training: A Longitudinal Path Analysis in a Randomized Controlled Trial Among Caregivers of People With Mental Illness

Background: There is a paucity of research on mediators of change, within compassion training programs. The aim was to investigate the mediators, of an 8-week compassion cultivation training (CCT) program, on the effect of psychological distress on caregivers of people with a mental illness. Method: Longitudinal path models in a randomized controlled trial (RCT). One hundred ninety-two participants were assessed for eligibility, and 161 participants were included into the trial and randomized. The main outcome was psychological distress measured by the Depression, Anxiety and Stress scale at 6 months. Mediators included self-compassion (SC), mindfulness (FM), emotion regulation (ER), emotion suppression (ES), and cognitive reappraisal (CR). Baseline, post, and 3- and 6-month follow-up measurements were collected. Results: The mediated effects for CCT are as follows: depression at 6 months: SC: -1.81 (95% CI: -3.31 to -0.31); FM: -1.98 (95% CI: -3.65 to -0.33); ER: -0.14 (95% CI: -1.31 to 1.02); anxiety at 6 months: SC: -0.71 (95% CI: -1.82 to 0.40); FM: -1.24 (95% CI: -2.39 to -0.09); ER: 0.18 (95% CI: -1.04 to 1.40); stress at 6 months: SC: -1.44 (95% CI: -2.84 to -0.05); FM: -2.17 (95% CI: -3.63 to -0.71); ER: -0.27 (95% CI: -1.51 to 0.98). Conclusion: Mindfulness and self-compassion are important components in reducing psychological distress experienced by informal caregivers of people with a mental illness. Results contribute to the knowledge about the underlying mechanisms of CCT.

How and for whom does supportive adjustment to multiple sclerosis cognitive-behavioural therapy work? A mediated moderation analysis

The supportive adjustment for multiple sclerosis (saMS) randomised controlled trial showed cognitive behavioural therapy (CBT) reduced distress at 12-months compared to supportive listening (SL). Larger changes in distress and functional impairment following CBT occurred in participants with clinical distress at baseline. This secondary analysis investigates whether CBT treatment effects occur through pre-defined CBT mechanisms of change in the total cohort and clinically distressed subgroup. 94 participants were randomised to saMS CBT or SL. Primary outcomes were distress and functional impairment (12 months). Mediators included cognitive-behavioural variables at post-treatment (15 weeks). Structural equation mediation and mediated-moderation models adjusting for baseline confounders assessed mediation overall and by distress level. Significant mediation was found but only for those with clinical distress at baseline. Illness acceptance (-0.20, 95% confidence interval -0.01 to -0.46) and reduced embarrassment avoidance behaviours (-0.22, -0.02 to -0.58) mediated CBT's effect on distress. Changes in beliefs about processing emotions (-0.19, -0.001 to -0.46) mediated CBT's effect on functional impairment. saMS CBT had effects on distress and functional impairment via some of the hypothesised mechanisms drawn from a theoretical model of adjustment for MS but only among participants with clinical distress at baseline. Increasing acceptance and emotional expression and decreasing embarrassment avoidance improves MS adjustment.

Beyond intervention into daily life: A systematic review of generalisation following social communication interventions for young children with autism

Researchers have generally considered autistic individuals to have difficulties generalising learned skills across novel contexts. Successful generalisation is necessary for an intervention to have benefits in everyday life beyond the original learning environment. We conducted a systematic review of randomised controlled trials of early social communication interventions for children with autism in order to explore generalisation and its measurement. We identified nine RCTs that provided evidence of initial target learning and measured generalisation, of which eight demonstrated at least some successful generalisation across people, settings, and/or activities. The findings did not support the widely reported generalisation 'difficulties' associated with autism. However, generalisation was not consistent across all skills within studies, and one study found no generalisation despite evidence for initial target learning within the intervention context. In general, there are few methodologically sound social communication intervention studies exploring generalisation in autism and no consensus on how it should be measured. In particular, failure to demonstrate initial learning of target skills within the intervention setting and an absence of formal mediation analyses of the hypothesised mechanisms limit current research. We outline a framework within which measurement of generalisation can be considered for use in future trials. To maximise the effectiveness of interventions, the field needs to gain a better understanding of the nature of generalisation among autistic individuals and what additional strategies may further enhance learning. Autism Res 2020, 13: 506-522. © 2020 The Authors. Autism Research published by International Society for Autism Research published by Wiley Periodicals, Inc. LAY SUMMARY: It is generally considered that autistic individuals experience difficulties applying things they have learned in one context into different settings (e.g. from school to home). This is important to consider for intervention studies. Our review does not support a complete lack of generalisation but instead suggests that after early social communication intervention, autistic children can transfer some skills to new contexts. Overall, there is limited research in this area and further work is needed.

Impact of telephone delivered case-management on the effectiveness of collaborative care for depression and anti-depressant use: A systematic review and meta-regression

BACKGROUND

The health service delivery framework collaborative care is an effective intervention for depression. However, uncertainties remain about how to optimise its delivery at scale. Structured case management is a core component of collaborative care; its delivery via the telephone may improve access.

AIMS

To examine using meta-regression if telephone delivered case management diminishes the clinical effectiveness of collaborative care on depressive symptoms and anti-depressant use relative to face-to-face delivery methods.

METHODS

Randomised controlled trials were eligible if they included collaborative care interventions for adults with depression identified using self-report measures or diagnostic interviews and reported depression outcomes. Sociodemographics, intervention characteristics, depressive symptoms, and anti-depressant use were extracted. Random effects univariable and multivariable meta-regression analyses were used to examine the moderating effect of telephone delivered case-management on outcomes.

RESULTS

Ninety-four trials were identified comprising of 103 comparisons across 24, 132 participants with depression outcomes and 67 comparisons from 15,367 participants with anti-depressant use outcomes. Telephone delivered case management did not diminish the effects of collaborative care on depressive symptoms (β = -0.01, 95% CI -0.12 to 0.10; p = 0.86). Telephone delivered case management decreased anti-depressant medication use (relative risk 0.76, 95% CI 0.63 to 0.92; p = 0.005); this effect remained when assessed simultaneously alongside other study-level moderators of collaborative care.

CONCLUSION

Using remote platforms such as the telephone to deliver case management may be a feasible way to implement collaborative care with no loss of effectiveness on depressive symptoms. However, adherence to anti-depressant medication may decrease when telephone case management is used.