Students as change agents: new ways of engaging with learning and teaching in higher education

This is a set of practitioner resources for those wanting to set up student-based research projects in their institutions

Psychosocial adversity and adolescents’ mental health problems:Moderating influences of basal cortisol, resting heart rate and Dopamine Receptor D4

Exposure to stressors is a well-established risk factor for psychopathology, both externalizing (aggressive and rule-breaking) and internalizing (mood and anxiety) problems, but affects some individuals more than others. Central to this dissertation are three biological factors that may increase or decrease the risk of psychopathology after exposure to stressors (thus reflecting susceptibility or resilience): basal cortisol level upon waking, resting heart rate, and the Dopamine D4 Receptor 7-repeat allele (DRD4-7R). The results showed that all three biological factors significantly changed the risk of psychopathology after exposure to stressors, although findings on basal cortisol were not consistent. The results also showed that the influence of basal cortisol and resting heart rate on the relationship between stressors and psychopathology was dependent on the degree of general vulnerability, measured as parental psychiatric history. However, effects were small and not always in the expected direction. Therefore, it seems unlikely that a single biological measure such as basal cortisol, resting heart rate, or a genetic polymorphism will someday be useful to the clinical practice in terms of risk assessment or in determining treatment course. Future research may focus on combinations of established risk or resilience factors. The studies described in this dissertation are based on data from TRAILS (TRacking Adolescents’ Individual Lives Survey, www.trails.nl), both the population-based birth cohort (n = 2230) and the parallel clinic-referred cohort (n = 543) and the first three measurement waves when participants were on average 11, 13.5, and 16 years old

Chronic Stressors and Adolescents' Externalizing Problems:Genetic Moderation by Dopamine Receptor D4. The TRAILS Study

The existing literature does not provide consistent evidence that carriers of the Dopamine D4 Receptor 7-repeat allele are more sensitive to adverse environmental influences, resulting in enhanced externalizing problems, compared to noncarriers. One explanation is that the adverse influences examined in prior studies were not severe, chronic, or distressing enough to reveal individual differences in sensitivity reflected by DRD4-7R. This study examined whether the 7-repeat allele moderated the association between chronic stressors capturing multiple stressful aspects of individuals' lives and externalizing problems in adolescence. We expected that chronic stressor levels would be associated with externalizing levels only in 7-repeat carriers. Using Linear Mixed Models, we analyzed data from 1621 Dutch adolescents (52.2% boys), obtained in three measurement waves (mean age approximately 11, 13.5, and 16 years) from the TRacking Adolescents' Individual Lives Survey (TRAILS) population-based birth cohort and the parallel clinic-referred cohort. Across informants, we found that higher levels of chronic stressors were related to higher externalizing levels in 7-repeat carriers but not in noncarriers, as hypothesized. Although previous studies on the 7-repeat allele as a moderator of environmental influences on adolescents' externalizing problems have not convincingly demonstrated individual differences in sensitivity to adverse environmental influences, our findings suggest that adolescent carriers of the Dopamine D4 Receptor 7-repeat allele are more sensitive to chronic, multi-context stressors than noncarriers

A multiverse analysis of early attempts to replicate memory suppression with the Think/No-think Task

In 2001, Anderson and Green [2001. Suppressing unwanted memories by executive control. Nature, 410(6826), 366-369] showed memory suppression using a novel Think/No-think (TNT) task. When participants attempted to prevent studied words from entering awareness, they reported fewer of those words than baseline words in subsequent cued recall (i.e., suppression effect). The TNT literature contains predominantly positive findings and few null-results. Therefore we report unpublished replications conducted in the 2000s (N = 49; N = 36). As the features of the data obtained with the TNT task call for a variety of plausible solutions, we report parallel "universes" of data-analyses (i.e., multiverse analysis) testing the suppression effect. Two published studies (Wessel et al., 2005. Dissociation and memory suppression: A comparison of high and low dissociative individuals' performance on the Think-No think Task. Personality and Individual Differences, 39(8), 1461-1470, N = 68; Wessel et al., 2010. Cognitive control and suppression of memories of an emotional film. Journal of Behavior Therapy and Experimental Psychiatry, 41(2), 83-89. https://doi.org/10.1016/j.jbtep.2009.10.005, N = 80) were reanalysed in a similar fashion. For recall probed with studied cues (Same Probes, SP), some tests (sample 3) or all (samples 2 and 4) showed statistically significant suppression effects, whereas in sample 1, only one test showed significance. Recall probed with novel cues (Independent Probes, IP) predominantly rendered non-significant results. The absence of statistically significant IP suppression effects raises problems for inhibition theory and its implication that repression is a viable mechanism of forgetting. The pre-registration, materials, data, and code are publicly available (https://osf.io/qgcy5/).</p

Chronic Stress and Adolescents' Mental Health:Modifying Effects of Basal Cortisol and Parental Psychiatric History. The TRAILS Study

Large individual differences in adolescent mental health following chronic psychosocial stress suggest moderating factors. We examined two established moderators, basal cortisol and parental psychiatric history, simultaneously. We hypothesized that individuals with high basal cortisol, assumed to indicate high context sensitivity, would show relatively high problem levels following chronic stress, especially in the presence of parental psychiatric history. With Linear Mixed Models, we investigated the hypotheses in 1917 Dutch adolescents (53.2 % boys), assessed at ages 11, 13.5, and 16. Low basal cortisol combined with the absence of a parental psychiatric history increased the risk of externalizing but not internalizing problems following chronic stress. Conversely, low basal cortisol combined with a substantial parental psychiatric history increased the risk of internalizing but not externalizing problems following chronic stress. Thus, parental psychiatric history moderated stress- cortisol interactions in predicting psychopathology, but in a different direction than hypothesized. We conclude that the premise that basal cortisol indicates context sensitivity may be too crude. Context sensitivity may not be a general trait but may depend on the nature of the context (e.g., type or duration of stress exposure) and on the outcome of interest (e.g., internalizing vs. externalizing problems). Although consistent across informants, our findings need replication

The Role of Basal Cortisol in Predicting Change in Mental Health Problems Across the Transition to Middle School

Purpose: The period in which the transition to middle school occurs is marked by major changes in social context, social rules, and scholastic responsibilities. Some adolescents thrive during this period whereas others are overwhelmed and fail to cope adequately with their changing environment. We investigated basal cortisol upon waking as a predictor of change in mental health problems across the transition to middle school. By taking into account the transition experience, we extend prior findings that high basal cortisol predicts deteriorated mental health after the transition. In individuals with high awakening cortisol, we expected mental health problems to increase after negative transition experiences and to decrease after positive transition experiences, reflecting differential susceptibility. Evidence for the former but not the latter would suggest diathesis-stress. Methods: Data from 1,664 subjects were obtained from two measurement waves (mean ages, 11 and 13.5 years) of the TRacking Adolescents' Individual Lives Survey. Using linear regression, we investigated effects of awakening cortisol level, school transition experience, and their hypothesized interaction on change in mental health problems. Results: We found that a negative but not a positive experience was predictive of change in mental health. Importantly, our results showed that a negative experience predicts deteriorated mental health only in adolescents with high awakening cortisol but not in adolescents with low awakening cortisol. This finding was robust across informants. The converse, high awakening cortisol predicting decreasing mental health problems after a positive transition was not found. Conclusions: These results support the diathesis-stress model but not the differential susceptibility hypothesis. (c) 2015 Society for Adolescent Health and Medicine. All rights reserved

Models predict change in plasma triglyceride concentrations and long-chain n-3 polyunsaturated fatty acid proportions in healthy participants after fish oil intervention

Introduction: Substantial response heterogeneity is commonly seen in dietary intervention trials. In larger datasets, this variability can be exploited to identify predictors, for example genetic and/or phenotypic baseline characteristics, associated with response in an outcome of interest. Objective: Using data from a placebo-controlled crossover study (the FINGEN study), supplementing with two doses of long chain n-3 polyunsaturated fatty acids (LC n-3 PUFAs), the primary goal of this analysis was to develop models to predict change in concentrations of plasma triglycerides (TG), and in the plasma phosphatidylcholine (PC) LC n-3 PUFAs eicosapentaenoic acid (EPA) + docosahexaenoic acid (DHA), after fish oil (FO) supplementation. A secondary goal was to establish if clustering of data prior to FO supplementation would lead to identification of groups of participants who responded differentially. Methods: To generate models for the outcomes of interest, variable selection methods (forward and backward stepwise selection, LASSO and the Boruta algorithm) were applied to identify suitable predictors. The final model was chosen based on the lowest validation set root mean squared error (RMSE) after applying each method across multiple imputed datasets. Unsupervised clustering of data prior to FO supplementation was implemented using k-medoids and hierarchical clustering, with cluster membership compared with changes in plasma TG and plasma PC EPA + DHA. Results: Models for predicting response showed a greater TG-lowering after 1.8 g/day EPA + DHA with lower pre-intervention levels of plasma insulin, LDL cholesterol, C20:3n-6 and saturated fat consumption, but higher pre-intervention levels of plasma TG, and serum IL-10 and VCAM-1. Models also showed greater increases in plasma PC EPA + DHA with age and female sex. There were no statistically significant differences in PC EPA + DHA and TG responses between baseline clusters. Conclusion: Our models established new predictors of response in TG (plasma insulin, LDL cholesterol, C20:3n-6, saturated fat consumption, TG, IL-10 and VCAM-1) and in PC EPA + DHA (age and sex) upon intervention with fish oil. We demonstrate how application of statistical methods can provide new insights for precision nutrition, by predicting participants who are most likely to respond beneficially to nutritional interventions