Using parent-offspring pairs and trios to estimate indirect genetic effects in education.

We investigated indirect genetic effects (IGEs), also known as genetic nurture, in education with a novel approach that uses phased data to include parent-offspring pairs in the transmitted/nontransmitted study design. This method increases the power to detect IGEs, enhances the generalizability of the findings, and allows for the study of effects by parent-of-origin. We validated and applied this method in a family-based subsample of adolescents and adults from the Lifelines Cohort Study in the Netherlands (N = 6147), using the latest genome-wide association study data on educational attainment to construct polygenic scores (PGS). Our results indicated that IGEs play a role in education outcomes in the Netherlands: we found significant associations of the nontransmitted PGS with secondary school level in youth between 13 and 24 years old as well as with education attainment and years of education in adults over 25 years old (ß = 0.14, 0.17 and 0.26, respectively), with tentative evidence for larger maternal IGEs. In conclusion, we replicated previous findings and showed that including parent-offspring pairs in addition to trios in the transmitted/nontransmitted design can benefit future studies of parental IGEs in a wide range of outcomes.

Family dysfunction, stressful life events, and mental health problems across development in the offspring of parents with an affective disorder.

BACKGROUND: Offspring of parents with affective disorders (OAD) are at risk of developing a wide range of mental disorders. Deficits in the rearing environment and high levels of stress are well-known risk factors for negative outcomes in OAD. Building on prior research, we aim to examine the longitudinal relationships between family dysfunction, stressful life events, and mental health in OAD and control offspring of parents with no affective disorder. In the present study, we hypothesized that high levels of family dysfunction would be associated with more internalizing and externalizing problems across time in OAD than in controls, and that family dysfunction would mediate the relationship between stressful life events in adolescence and poor mental health in adulthood, particularly in OAD. METHODS: As part of the TRacking Adolescents' Lives Survey (TRAILS), 2230 participants (51% female, Mage = 11.1 years, SD = 0.6, at baseline) and their parents completed measures across six time points, spanning 15 years. Mental health, family dysfunction, and stressful life events were assessed with the Youth and Adult Self-Report, Family Assessment Device, and an in-house measure, respectively. RESULTS: Multi-group structured equation modeling revealed that family dysfunction was linked to internalizing and externalizing problems in OAD, but not controls, across time. Risk status did not moderate family dysfunction's mediation of the relationship between stressful life events and negative outcomes in adulthood. CONCLUSIONS: OAD show high sensitivity to dysfunction in the rearing environment across childhood and adolescence, which supports the use of family based interventions to prevent the development of mental disorders in high-risk youth.

Genomics Research of Lifetime Depression in the Netherlands: The BIObanks Netherlands Internet Collaboration (BIONIC) Project.

In this cohort profile article we describe the lifetime major depressive disorder (MDD) database that has been established as part of the BIObanks Netherlands Internet Collaboration (BIONIC). Across the Netherlands we collected data on Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5) lifetime MDD diagnosis in 132,850 Dutch individuals. Currently, N = 66,684 of these also have genomewide single nucleotide polymorphism (SNP) data. We initiated this project because the complex genetic basis of MDD requires large population-wide studies with uniform in-depth phenotyping. For standardized phenotyping we developed the LIDAS (LIfetime Depression Assessment Survey), which then was used to measure MDD in 11 Dutch cohorts. Data from these cohorts were combined with diagnostic interview depression data from 5 clinical cohorts to create a dataset of N = 29,650 lifetime MDD cases (22%) meeting DSM-5 criteria and 94,300 screened controls. In addition, genomewide genotype data from the cohorts were assembled into a genomewide association study (GWAS) dataset of N = 66,684 Dutch individuals (25.3% cases). Phenotype data include DSM-5-based MDD diagnoses, sociodemographic variables, information on lifestyle and BMI, characteristics of depressive symptoms and episodes, and psychiatric diagnosis and treatment history. We describe the establishment and harmonization of the BIONIC phenotype and GWAS datasets and provide an overview of the available information and sample characteristics. Our next step is the GWAS of lifetime MDD in the Netherlands, with future plans including fine-grained genetic analyses of depression characteristics, international collaborations and multi-omics studies.

Childhood abuse v. neglect and risk for major psychiatric disorders.

BACKGROUND: Childhood maltreatment (CM) is a strong risk factor for psychiatric disorders but serves in its current definitions as an umbrella for various fundamentally different childhood experiences. As first step toward a more refined analysis of the impact of CM, our objective is to revisit the relation of abuse and neglect, major subtypes of CM, with symptoms across disorders. METHODS: Three longitudinal studies of major depressive disorder (MDD, N = 1240), bipolar disorder (BD, N = 1339), and schizophrenia (SCZ, N = 577), each including controls (N = 881), were analyzed. Multivariate regression models were used to examine the relation between exposure to abuse, neglect, or their combination to the odds for MDD, BD, SCZ, and symptoms across disorders. Bidirectional Mendelian randomization (MR) was used to probe causality, using genetic instruments of abuse and neglect derived from UK Biobank data (N = 143 473). RESULTS: Abuse was the stronger risk factor for SCZ (OR 3.51, 95% CI 2.17-5.67) and neglect for BD (OR 2.69, 95% CI 2.09-3.46). Combined CM was related to increased risk exceeding additive effects of abuse and neglect for MDD (RERI = 1.4) and BD (RERI = 1.1). Across disorders, abuse was associated with hallucinations (OR 2.16, 95% CI 1.55-3.01) and suicide attempts (OR 2.16, 95% CI 1.55-3.01) whereas neglect was associated with agitation (OR 1.24, 95% CI 1.02-1.51) and reduced need for sleep (OR 1.64, 95% CI 1.08-2.48). MR analyses were consistent with a bidirectional causal effect of abuse with SCZ (IVWforward = 0.13, 95% CI 0.01-0.24). CONCLUSIONS: Childhood abuse and neglect are associated with different risks to psychiatric symptoms and disorders. Unraveling the origin of these differences may advance understanding of disease etiology and ultimately facilitate development of improved personalized treatment strategies.

Uncovering the genetic architecture of broad antisocial behavior through a genome-wide association study meta-analysis.

Despite the substantial heritability of antisocial behavior (ASB), specific genetic variants robustly associated with the trait have not been identified. The present study by the Broad Antisocial Behavior Consortium (BroadABC) meta-analyzed data from 28 discovery samples (N = 85,359) and five independent replication samples (N = 8058) with genotypic data and broad measures of ASB. We identified the first significant genetic associations with broad ASB, involving common intronic variants in the forkhead box protein P2 (FOXP2) gene (lead SNP rs12536335, p = 6.32 × 10-10). Furthermore, we observed intronic variation in Foxp2 and one of its targets (Cntnap2) distinguishing a mouse model of pathological aggression (BALB/cJ strain) from controls (BALB/cByJ strain). Polygenic risk score (PRS) analyses in independent samples revealed that the genetic risk for ASB was associated with several antisocial outcomes across the lifespan, including diagnosis of conduct disorder, official criminal convictions, and trajectories of antisocial development. We found substantial genetic correlations of ASB with mental health (depression rg = 0.63, insomnia rg = 0.47), physical health (overweight rg = 0.19, waist-to-hip ratio rg = 0.32), smoking (rg = 0.54), cognitive ability (intelligence rg = -0.40), educational attainment (years of schooling rg = -0.46) and reproductive traits (age at first birth rg = -0.58, father's age at death rg = -0.54). Our findings provide a starting point toward identifying critical biosocial risk mechanisms for the development of ASB.

Annual Research Review: Stability of psychopathology: lessons learned from longitudinal population surveys.

BACKGROUND: Psychopathology has been long recognized as a fluctuating process with various expressions over time, which can only be properly understood if we follow individuals and their social context from childhood up until adulthood. Longitudinal population-based studies have yielded powerful data to analyze this process. However, the resulting publications have not been reflected upon with regard to (a) the homotypic and heterotypic stability of internalizing and externalizing problems and (b) how transactions between psychopathology and environmental factors shape its development. METHODS: In this narrative review, we primarily focused on population-based studies that followed cohorts repeatedly from an early age (<18 years) onwards, across multiple stages of development, using statistical methods that permit inferences about within-person bidirectional associations between internalizing and externalizing problems or psychopathology-environment transactions. RESULTS: There is robust evidence that mental health problems in childhood or adolescence predict psychiatric problems later in development. In terms of the broadband domains internalizing and externalizing problems, homotypic stability greatly exceeds heterotypic stability and transitions from purely internalizing to purely externalizing problems or vice versa are rare. Homotypic rank-order stabilities seem to increase over time. Findings regarding transactions with environmental factors are less robust, due to widely varying research topics and designs, and a scarcity of studies that separated between-person differences from within-person changes. In general, however, the literature shows little consistent evidence for substantial mutual prospective influences between psychopathology and environmental factors. CONCLUSIONS: Longitudinal surveys have strongly augmented insight into homotypic and heterotypic stability and change. Attempts to unravel the myriad of risk and protective factors that place individuals on particular pathways or deflect them from these pathways are still in a pioneering phase and have not yet generated robust findings. As a way forward, we propose to join forces and develop a common risk factor taxonomy.

Genetic confounding in bullying research: Causal claims revisited.

Bullying research has shown repeatedly that victims of bullying have an increased risk for later internalizing problems and bullies have an increased risk for later externalizing problems. Bullying involvement is often, either explicitly or implicitly, presented as part of a causal mechanism for maladjustment. However, genetic vulnerability may confound the reported associations. This study examined to what extent genetic vulnerability can account for the reported associations between bullying involvement (age 11-14) and later internalizing and externalizing problems (age 16), using data from the TRacking Adolescents' Individual Lives Survey (n = 1604). Because polygenic scores capture only a fraction of the total genetic effect, they were extrapolated to the size of single-nucleotide polymorphism and twin heritability estimates to examine genetic confounding while controlling for (hypothetical) polygenic scores that fully capture the genetic effect. Genetic vulnerability for internalizing and externalizing problems confounded, respectively, the association between bullying victimization and later internalizing problems, and the association between bullying perpetration and later externalizing problems. As such, this study showcases a method that can be broadly used to assess the magnitude of genetic confounding. Caution is, however, warranted in interpreting particularly the less straightforward extrapolations of polygenic scores to the size of twin heritability estimates.

Direct and indirect associations between childhood adversity and emotional and behavioral problems at age 14: A network analytical approach.

We applied network analysis combined with community detection algorithms to examine how adverse experiences (AEs) (e.g., abuse, bullying victimization, financial difficulties) are, individually and conjunctively, associated with emotional and behavioral problems at age fourteen in the Dutch TRacking Adolescents' Individual Lives Survey (TRAILS, N = 1880, 52.2% female). We found that bullying victimization, peer rejection, parental mental health problems, emotional abuse, and sexual abuse were the only AEs directly contributing to risk of emotional problems. Parental divorce and emotional abuse were the only AEs directly contributing to risk of behavioral problems. Most AEs (e.g., parental employment, parental physical illness) were not conditionally associated with emotional and behavioral problems but may nevertheless contribute to emotional and behavioral problems via associations with other AEs (e.g., parental unemployment and emotional abuse). Community detection algorithms suggested that many of the AEs cluster together (e.g., physical abuse, emotional abuse, and sexual abuse; financial difficulties and parental unemployment), sometimes with emotional and behavioral problems (e.g., bullying victimization, peer rejection and emotional problems). Our findings shed light on how individual AEs contribute to risks of emotional and behavioral problems directly, and indirectly through associations with other AEs.

Educational level, attention problems, and externalizing behaviour in adolescence and early adulthood: the role of social causation and health-related selection-the TRAILS study.

Social causation and health-related selection may contribute to educational differences in adolescents' attention problems and externalizing behaviour. The social causation hypothesis posits that the social environment influences adolescents' mental health. Conversely, the health-related selection hypothesis proposes that poor mental health predicts lower educational attainment. From past studies it is unclear which of these mechanisms predominates, as attention problems and externalizing behaviour have the potential to interfere with educational attainment, but may also be affected by differences in the educational context. Furthermore, educational gradients in mental health may reflect the impact of 'third variables' already present in childhood, such as parental socioeconomic status (SES), and IQ. We investigated both hypotheses in relation to educational differences in externalizing behaviour and attention problems throughout adolescence and young adulthood. We used data from a Dutch cohort (TRAILS Study; n = 2229), including five measurements of educational level, externalizing behaviour, and attention problems from around age 14-26 years. First, we evaluated the directionality in longitudinal associations between education, externalizing behaviour, and attention problems with and without adjusting for individual differences using fixed effects. Second, we assessed the role of IQ and parental SES in relation to attention problems, externalizing behaviour, and educational level. Attention problems predicted decreases in education throughout all of adolescence and young adulthood. Differences in parental SES contributed to increases in externalizing behaviour amongst the lower educational tracks in mid-adolescence. Childhood IQ and parental SES strongly predicted education around age 14. Parental SES, but not IQ, also predicted early adolescent attention problems and externalizing behaviour. Our results provide support for the health-related selection hypothesis in relation to attention problems and educational attainment. Further, our results highlight the role of social causation from parental SES in determining adolescent educational level, attention problems, and externalizing behaviour.

Association between adolescent oral contraceptive use and future major depressive disorder: a prospective cohort study.

BACKGROUND: Because of the widespread use of oral contraceptives (OCs) and the devastating effects of depression both on an individual and a societal level, it is crucial to understand the nature of the previously reported relationship between OC use and depression risk. Insight into the impact of analytical choices on the association is important when interpreting available evidence. Hence, we examined the association between adolescent OC use and subsequent depression risk in early adulthood analyzing all theoretically justifiable models. METHODS: Data from the prospective cohort study TRacking Adolescents' Individual Lives Survey, among women aged 13-25 years were used. Adolescent OC use (ages 16-19 years) was used as a predictor and major depressive disorder (MDD) in early adulthood (ages 20-25 years), as assessed by the Diagnostic and Statistical Manual of Mental Disorders-IV oriented Lifetime Depression Assessment Self-Report and the Composite International Diagnostic Interview, was used as an outcome. A total of 818 analytical models were analyzed using Specification Curve Analysis in 534 adolescent OC users and 191 nonusers. RESULTS: Overall, there was an association of adolescent OC use and an episode of MDD in early adulthood [median odds ratio (OR)median = 1.41; ORmin = 1.08; ORmax = 2.18, p < .001], which was driven by the group of young women with no history of MDD (ORmedian = 1.72; ORmin = 1.21; ORmax = 2.18, p < .001). CONCLUSIONS: In summary, adolescent OC use was associated with a small but robust increased risk for experiencing an episode of MDD, especially among women with no history of MDD in adolescence. Understanding the potential side effects of OCs will help women and their doctors to make informed choices when deciding among possible methods of birth control.

Continuity of Psychopathology Throughout Adolescence and Young Adulthood.

OBJECTIVE: This study tested two opposing hypotheses on the continuity of psychopathology throughout adolescence and young adulthood; differentiation versus dynamic mutualism. Differentiation predicts that co-occurrence decreases, while dynamic mutualism predicts that co-occurrence increases due to causal interactions amongst mental health problems. METHOD: Using data from the Dutch TRacking Adolescents' Individual Lives Survey (n = 2228, 51% female), we studied the development of self-reported internalizing, externalizing, and attention problems at ages 11 to 26 across six waves. Random-intercept cross-lagged panel modeling was employed to distinguish within-person development from stable between-person processes. RESULTS: Large stable between-person associations indicated that adolescents with internalizing problems tended to have both externalizing and attention problems as well. On a within-person level, mental health problems showed partial stability and strong cross-sectional co-occurrence. Within-wave associations of internalizing with externalizing or attention problems decreased between age 11 and 16 years, after which they increased again. Little heterotypic continuity was found: age 11 externalizing predicted age 13 attention, which in turn predicted age 16 externalizing problems, and internalizing predicted externalizing problems across ages 22 to 26. Findings were similar for males and females. CONCLUSIONS: Our findings suggest co-occurrence decreases during early and middle adolescence, supporting differentiation. While co-occurrence increased again into young adulthood, this could not be labeled as dynamic mutualism because little evidence for heterotypic continuity was found in this phase of life. The strong stable links between internalizing, externalizing, and attention problems stress the importance of targeting these mental health problems and their shared risk factors together.

Self-control, Mental Health Problems, and Family Functioning in Adolescence and Young Adulthood: Between-person Differences and Within-person Effects.

Adolescents' self-control develops in the context of mental health and family functioning, but it is unclear how the interplay of self-control, mental health, and family functioning unfolds across time within individuals. Separating within-person from between-person effects, random-intercept cross-lagged panel models were applied to adolescents (from ages 11 to 26) from a Dutch cohort (n = 2228, 51% female). Adolescents with low self-control were likely to have mental health problems and poorly functioning families. Although within-person changes in the study variables were not meaningfully associated in a reciprocal manner, changes in self-control and mental health were concurrently associated. This suggests that besides stable connections between self-control, mental health, and family functioning in adolescence and young adulthood, changes in self-control and mental health are developmentally linked as well.

Editorial: Factualities - establishing empirical truths in child psychology and psychiatry.

Empirical science is a fact-finding enterprise. This raises the question when we know enough about a particular topic to draw firm conclusions and can stop searching for additional evidence in order to save efforts for issues that are less well-established. Clarity on when scientific evidence has passed the stage of to-be-tested hypotheses is important, and setting up criteria for such stopping rules is a necessary as well as thought-provoking challenge. Not only over-investigating phenomena is undesirable but the opposite, falsely assuming beliefs to be facts, as well. Two common reasons for such misperceptions are that negative news is more likely to spread around than positive news (negativity instinct), and that individuals tend to look at problems from always the same perspective (single-perspective instinct). Our field is not immune to those instincts: child psychologists and psychiatrists tend to focus on messages suggesting that the burden of children´s mental health problems calls for more intervention and research, rather than on reports that the majority of children are doing quite well. This focus on problems may obscure the reality that the vast majority of children and adolescents never experience severe mental health problems, despite the challenges of growing up in a complex world.

Risk factors in preadolescent boys and girls for the development of eating pathology in young adulthood.

OBJECTIVE: Despite a growing literature on potential risk factors for eating disorders, longitudinal research starting before adolescence is scarce, and little is known about risk factors in males. We investigated risk factors in preadolescent boys and girls for the development of eating pathology in adolescence and young adulthood. METHOD: This study is part of TRAILS (TRacking Adolescents' Individual Lives Survey), a Dutch population-based cohort study (N = 2,229) from preadolescence into adulthood. Potential risk factors were measured at age 11, based on self-report, reports of one of the parents, and records of the Preventive Child Healthcare. Variables included sociodemographic variables, pregnancy and perinatal factors, eating- and weight-related factors, psychological functioning, stressful experiences and family factors. At age 19, two-stage screening including interviews by eating disorder experts was used to examine the prevalence of eating disorders. At age 22 and 26, eating pathology was assessed by the Eating Disorder Diagnostic Scale. RESULTS: Preadolescent anxious distress and high weight were associated with eating pathology in adolescence and young adulthood in both boys and girls. Overeating in preadolescence was found to be a prodromal symptom of eating disorders during late adolescence. No evidence was found for sex-specific risk factors. DISCUSSION: Anxious preadolescents with high weight are at increased risk for the development of eating pathology later on. Clinicians should be aware of eating disorder symptoms - like overeating - in this high-risk group of children, and could consider an early intervention to prevent the development of full-blown eating disorders.

Psychosocial and biological risk factors of anxiety disorders in adolescents: a TRAILS report.

Anxiety disorders are a common problem in adolescent mental health. Previous studies have investigated only a limited number of risk factors for the development of anxiety disorders concurrently. By investigating multiple factors simultaneously, a more complete understanding of the etiology of anxiety disorders can be reached. Therefore, we assessed preadolescent socio-demographic, familial, psychosocial, and biological factors and their association with the onset of anxiety disorders in adolescence. This study was conducted among 1584 Dutch participants of the TRacking Adolescents' Individual Lives Survey (TRAILS). Potential risk factors were assessed at baseline (age 10-12), and included socio-demographic (sex, socioeconomic status), familial (parental anxiety and depression), psychosocial (childhood adversity, temperament), and biological (body mass index, heart rate, blood pressure, cortisol) variables. Anxiety disorders were assessed at about age 19 years through the Composite International Diagnostic Interview (CIDI). Univariate and multivariate logistic regression analyses were performed with onset of anxiety disorder as a dependent variable and the above-mentioned putative risk factors as predictors. Of the total sample, 25.7% had a lifetime diagnosis of anxiety disorder at age 19 years. Anxiety disorders were twice as prevalent in girls as in boys. Multivariate logistic regression analysis showed that being female (OR = 2.38, p < .01), parental depression and anxiety (OR = 1.34, p = .04), temperamental frustration (OR = 1.31, p = .02) and low effortful control (OR = 0.76, p = .01) independently predicted anxiety disorders. We found no associations between biological factors and anxiety disorder. After exclusion of adolescents with an onset of anxiety disorder before age 12 years, being female was the only significant predictor of anxiety disorder. Being female was the strongest predictor for the onset of anxiety disorder. Psychological and parental psychopathology factors increased the risk of diagnosis of anxiety, but to a lesser extent. Biological factors (heart rate, blood pressure, cortisol, and BMI), at least as measured in the present study, are unlikely to be useful tools for anxiety prevention and intervention strategies.

Social Withdrawal and Romantic Relationships: A Longitudinal Study in Early Adulthood.

Involvement in romantic relationships is a salient developmental task in late adolescence and early adulthood, and deviations from normative romantic development are linked to adverse outcomes. This study investigated to what extent social withdrawal contributed to deviations from normative romantic development, and vice versa, and the interplay between withdrawal and couples' relationship perceptions. The sample included 1710 young adults (55-61% female) from the Tracking Adolescents' Individual Lives Survey cohort and their romantic partners. Data were collected across 4 waves, covering romantic relationships from ages 17 to 29 years. The results showed that higher withdrawal predicted a higher likelihood of romantic non-involvement by adulthood, consistently being single at subsequent waves, and entering one's first relationship when older. Withdrawal moderately decreased when youth entered their first relationship. Male's withdrawal in particular affected romantic relationship qualities and dynamics. These results provide new insights into the developmental sequelae of withdrawn young adults' romantic relationship development.

An evaluation of the efficacy of two add-on ecological momentary intervention modules for depression in a pragmatic randomized controlled trial (ZELF-i).

BACKGROUND: Depression treatment might be enhanced by ecological momentary interventions (EMI) based on self-monitoring and person-specific feedback. This study is the first to examine the efficacy of two different EMI modules for depression in routine clinical practice. METHODS: Outpatients starting depression treatment at secondary mental health services (N = 161; MIDS-DEPRESSION = 35.9, s.d. = 10.7; MAGE = 32.8, s.d. = 12.1; 46% male) participated in a pragmatic randomized controlled trial with three arms. Two experimental groups engaged in 28 days of systematic self-monitoring (5 times per day), and received weekly feedback on either positive affect and activities (Do-module) or negative affect and thinking patterns (Think-module). The control group received no additional intervention. Participants completed questionnaires on depressive symptoms (primary outcome), social functioning, and empowerment before and after the intervention period, and at four measurements during a 6-month follow-up period. RESULTS: Of the 90 (out of 110) participants who completed the intervention, 86% would recommend it. However, the experimental groups did not show significantly more or faster changes over time than the control group in terms of depressive symptoms, social functioning, and empowerment. Furthermore, the trajectories of the two EMI modules were very similar. CONCLUSIONS: We did not find statistical evidence that this type of EMI augments the efficacy of regular depression treatment, regardless of module content. We cannot rule out that EMIs have a positive impact on other domains or provide a more efficient way of delivering care. Nonetheless, EMI's promise of effectiveness has not materialized yet.

Measurement and genetic architecture of lifetime depression in the Netherlands as assessed by LIDAS (Lifetime Depression Assessment Self-report).

BACKGROUND: Major depressive disorder (MDD) is a common mood disorder, with a heritability of around 34%. Molecular genetic studies made significant progress and identified genetic markers associated with the risk of MDD; however, progress is slowed down by substantial heterogeneity as MDD is assessed differently across international cohorts. Here, we used a standardized online approach to measure MDD in multiple cohorts in the Netherlands and evaluated whether this approach can be used in epidemiological and genetic association studies of depression. METHODS: Within the Biobank Netherlands Internet Collaboration (BIONIC) project, we collected MDD data in eight cohorts involving 31 936 participants, using the online Lifetime Depression Assessment Self-report (LIDAS), and estimated the prevalence of current and lifetime MDD in 22 623 unrelated individuals. In a large Netherlands Twin Register (NTR) twin-family dataset (n ≈ 18 000), we estimated the heritability of MDD, and the prediction of MDD in a subset (n = 4782) through Polygenic Risk Score (PRS). RESULTS: Estimates of current and lifetime MDD prevalence were 6.7% and 18.1%, respectively, in line with population estimates based on validated psychiatric interviews. In the NTR heritability estimates were 0.34/0.30 (s.e. = 0.02/0.02) for current/lifetime MDD, respectively, showing that the LIDAS gives similar heritability rates for MDD as reported in the literature. The PRS predicted risk of MDD (OR 1.23, 95% CI 1.15-1.32, R2 = 1.47%). CONCLUSIONS: By assessing MDD status in the Netherlands using the LIDAS instrument, we were able to confirm previously reported MDD prevalence and heritability estimates, which suggests that this instrument can be used in epidemiological and genetic association studies of depression.

Editorial: Something special - the scientific challenges of rare risks.

Globalization has sparked international collaboration in our field, and this trend is expected to continue in the years to come. This offers excellent opportunities to learn more about the influence of children's sociocultural environments on their development and mental health. A particular challenge when studying risk factors across cultures and populations is that the risk associated with a particular exposure may depend on its prevalence: rarity tends to aggravate impact. This phenomenon complicates not only comparisons across cultures, but also those across subpopulations and time periods within a population. Moreover, it may counteract the effectiveness of risk-reducing public health efforts. On the bright side, the extent to which the impact of a risk factor is determined by its rarity provides researchers with valuable tools to deepen and sharpen theories about the nature and working mechanisms of that risk factor, with prevention and treatment strategies that also benefit youth in exceptional conditions as a likely consequence.

Temperament in preadolescence is associated with weight and eating pathology in young adulthood.

OBJECTIVE: Few longitudinal studies have investigated the role of temperament traits on weight and eating problems thus far. We investigated whether temperament in preadolescence influences body weight and the development of eating pathology in adolescence and young adulthood. METHOD: This study used data from TRAILS (Tracking Adolescents' Individual Lives Survey), a Dutch community cohort study (N = 2,230) from preadolescence into adulthood. At age 11, the temperament dimensions negative affectivity and effortful control were measured with the Early Adolescent Temperament Questionnaire-Revised. Body mass index (BMI) was measured at all assessment waves. At age 19, the prevalence of eating disorders was investigated by two-stage screening including interviews by eating disorder experts. At age 22 and 26, the Eating Disorder Diagnostic Scale was used to assess the level of eating pathology. RESULTS: Higher negative affectivity in preadolescence was associated with higher BMI and eating pathology in young adulthood. Lower effortful control in preadolescence was found to be a risk factor for the development of obesity in young adulthood. No association was found between effortful control in preadolescence and eating pathology in later life. DISCUSSION: Both negative affectivity and effortful control play a role in the development of weight or eating problems during adolescence.