Research review: gene-environment interaction research in youth depression - a systematic review with recommendations for future research

Psychobiological responses to choir singing and creative arts activities in children and adolescents with mental disorders: results of a pilot study

BACKGROUND

Children and adolescents living with mental health problems often experience stress and poor mood states, which may influence their quality of life and well-being. Arts interventions may improve mood and well-being and reduce physiological stress in this vulnerable population.

METHODS

A cohort of patients in child and adolescent psychiatry (N = 42; age range: 12-18 years) participated in one of four arts activities including choir singing (n = 11), textile design (n = 9), drama (n = 16), and clownery (n = 6). They were led by professional artists and delivered through five consecutive 90-min daily afternoon sessions over the course of 1 week. Questionnaires of mood and saliva samples before and after each session served to assess short-term psychobiological changes. In addition, patients reported their quality of life and well-being at the beginning and at the end of the 1‑week program.

RESULTS

Results showed that alertness was significantly enhanced after textile design (∆post-pre = 4.08, 95% CI [0.77, 7.39]) and after singing (∆post-pre = 2.20, 95% CI [-0.55, 4.94]). Moreover, mood tended to be positively affected by textile design (∆post-pre = 2.89, 95% CI [-0.39, 6.18]). Quality of life increased significantly after singing (∆post-pre = 5.49, 95% CI [1.05, 9.92]). Arts participation except singing was associated with significant reductions in salivary cortisol (sCort) (textile design ∆post-pre = -0.81 ng/mL, 95% CI [-1.48, -0.14]; drama ∆post-pre = -0.76 ng/mL, 95% CI [-1.28, -0.24]; clownery ∆post-pre = -0.74 ng/mL, 95% CI [-1.47, -0.01]). No significant changes were observed for well-being over the whole program and salivary immunoglobulin A (sIgA) after any of the arts activities.

DISCUSSION

These results suggest that arts participation can improve mood state and reduce stress in young people with mental disorders, but there is a need for further studies.

Adherence to the Mediterranean diet and depressive, anxiety, and stress symptoms in Spanish adolescents: results from the EHDLA study

Depression and anxiety are prevalent and disabling conditions among adolescents. The aim of this study was to examine the relationship between adherence to the Mediterranean diet (MD) and depressive, anxiety, and stress symptoms in adolescents. This cross-sectional study included a sample of 698 adolescent students from a region of Spain (mean age of 13.9 ± 1.5 years; 56.2% girls). Adherence to the MD was evaluated with the Mediterranean Diet Quality Index in children and adolescents (KIDMED). Mental health symptoms were measured with the Depression, Anxiety, and Stress Scale (DASS-21). Logistic regression models were performed, including a wide range of potential confounders. Compared to individuals with low adherence to the MD, those with moderate and high adherence had lower odds of experiencing depressive symptoms (odds ratio [OR] = 0.40, 95% confidence interval [CI] 0.24-0.65 and OR = 0.33, 95% CI 0.20-0.55, respectively), which were statistically significant even after adjustment. No significant associations were found regarding anxiety or stress symptoms. Therefore, according to our results, higher adherence to the MD is inversely related to having depressive symptoms among adolescents, regardless of socioeconomic, anthropometric, and lifestyle factors. Considering the deleterious effects of mental health problems in youths, further research on the role of nonpharmacological strategies for the prevention and treatment of depressive symptoms in adolescence is essential.

Childhood trauma, psychache, and depression among university students: a moderated mediation model

Background

Childhood trauma is a potential threat to depression and can have a lifelong impact on the mental health of university students. Our study aimed to construct a moderated mediation model to explore the relationship between childhood trauma, psychache, ambivalence over emotional expression, physical activity, and depression in university students.

Methods

A cross-sectional study was conducted in three universities in China, recruiting 476 university students using self-report questionnaires. The moderated mediation model was examined using the SPSS PROCESS model 21.

Results

Ambivalence over emotional expression (F=12.843), childhood trauma (F=117.639), and psychache (F=581.594) all had a significant positive effect on depression (p<0.001), explaining 2.9%, 21.7%, and 56.8% of the variance, respectively. On the chain of influence between childhood trauma and depression, the mediating effect of psychache, the moderating effect of ambivalence over emotional expression, and the moderating effect of physical activity are all significant the overall indirect effect value of the three is 0.287, accounting for 61.59% of the total effect.

Conclusion

This study investigated the relationship between childhood trauma, ambivalence over emotional expression, psychache, physical activity, and depression in university students. Future interventions should focus on developing good emotional expression among university students, increasing opportunities for physical activity, and reducing psychache to reduce depression.

The Effect of Peer Relationships on Adolescent Loneliness: The Role of Psychological Resilience and the OXTR Gene

Background

Based on the gene-environment interaction paradigm, this study explored the effect of peer relationships on adolescent loneliness and the role of psychological resilience and the oxytocin receptor gene (OXTR).

Methods

A survey was conducted in a sample of 619 adolescents, and their oral cells were collected for DNA extraction and genotyping.

Results

The results showed that (1) both peer relationships and psychological resilience significantly affected adolescent loneliness; (2) psychological resilience partially mediated the relationship between peer relationships and loneliness in adolescents; (3) OXTR gene rs53576 polymorphism moderated both the first and second half of the indirect pathway of the mediation model. Specifically, carriers of the rs53576 polymorphism A/A genotype showed a significantly enhanced effect of peer relationships on adolescent psychological resilience, while carriers of the rs53576 polymorphism G/G genotype showed a significantly enhanced effect of psychological resilience on adolescent loneliness.

Conclusion

These findings helped elucidate the developmental mechanisms of adolescent loneliness in terms of peer relationships, psychological resilience, and OXTR gene polymorphisms.

Gene-environment interactions in human health

Gene-environment interactions (G × E), the interplay of genetic variation with environmental factors, have a pivotal impact on human complex traits and diseases. Statistically, G × E can be assessed by determining the deviation from expectation of predictive models based solely on the phenotypic effects of genetics or environmental exposures. Despite the unprecedented, widespread and diverse use of G × E analytical frameworks, heterogeneity in their application and reporting hinders their applicability in public health. In this Review, we discuss study design considerations as well as G × E analytical frameworks to assess polygenic liability dependent on the environment, to identify specific genetic variants exhibiting G × E, and to characterize environmental context for these dynamics. We conclude with recommendations to address the most common challenges and pitfalls in the conceptualization, methodology and reporting of G × E studies, as well as future directions.

Cohort profile: BioMD-Y (biopsychosocial factors of major depression in youth) - a biobank study on the molecular genetics and environmental factors of depression in children and adolescents in Munich

PURPOSE

BioMD-Y is a comprehensive biobank study of children and adolescents with major depression (MD) and their healthy peers in Germany, collecting a host of both biological and psychosocial information from the participants and their parents with the aim of exploring genetic and environmental risk and protective factors for MD in children and adolescents.

PARTICIPANTS

Children and adolescents aged 8-18 years are recruited to either the clinical case group (MD, diagnosis of MD disorder) or the typically developing control group (absence of any psychiatric condition).

FINDINGS TO DATE

To date, four publications on both genetic and environmental risk and resilience factors (including FKBP5, glucocorticoid receptor activation, polygenic risk scores, psychosocial and sociodemographic risk and resilience factors) have been published based on the BioMD-Y sample.

FUTURE PLANS

Data collection is currently scheduled to continue into 2026. Research questions will be further addressed using available measures.

Genetics, epigenetics, and neurobiology of childhood-onset depression: an umbrella review

Depression is a serious and persistent psychiatric disorder that commonly first manifests during childhood. Depression that starts in childhood is increasing in frequency, likely due both to evolutionary trends and to increased recognition of the disorder. In this umbrella review, we systematically searched the extant literature for genetic, epigenetic, and neurobiological factors that contribute to a childhood onset of depression. We searched PubMed, EMBASE, OVID/PsychInfo, and Google Scholar with the following inclusion criteria: (1) systematic review or meta-analysis from a peer-reviewed journal; (2) inclusion of a measure assessing early age of onset of depression; and (3) assessment of neurobiological, genetic, environmental, and epigenetic predictors of early onset depression. Findings from 89 systematic reviews of moderate to high quality suggest that childhood-onset depressive disorders have neurobiological, genetic, environmental, and epigenetic roots consistent with a diathesis-stress theory of depression. This review identified key putative markers that may be targeted for personalized clinical decision-making and provide important insights concerning candidate mechanisms that might underpin the early onset of depression.

Serotonergic multilocus genetic variation moderates the association between interpersonal relationship and adolescent depressive symptoms

BACKGROUND

Research suggests that genetic variants linked to serotonin functioning moderate the association between environmental stressors and depressive symptoms, but examining gene-environment interactions with single polymorphisms limits power.

METHODS

A multilocus genetic profile score (MGPS) approach to measuring serotonergic multilocus genetic variation and examined interactions with interpersonal relationship, insomnia with depressive symptoms as outcomes in an adolescent sample (average age = 14.15 ± 0.63 years since first measurement; range: 13 to 15).

RESULTS

(1) interpersonal relationship predicted adolescent depressive symptoms; (2) insomnia mediated the effect of interpersonal relationships on adolescent depressive symptoms; (3) the THP2 gene rs4570625 polymorphism G allele was a key risk factor for depressive symptom, and the MGPS moderated the effects of teacher-student relationship and insomnia on adolescent depressive symptom. Specifically, as the MGPS increased, the effects of insomnia on adolescent depressive symptom were enhanced; further, when the MGPS score increased, the effect of teacher-student relationship on depression showed a similar phenomenon with an increased slope and enhanced prediction; and (4) the results of sensitivity analysis showed that multilocus genetic interaction with the environment had a better explanatory power and stability for depression than single polymorphism studies.

CONCLUSION

MGPS provides substantial power to examine gene-environmental interactions linked to affective outcomes among adolescents.

Future self-continuity and depression among college students: The role of presence of meaning and perceived social support

INTRODUCTION

Future self-continuity has been shown to have a protective effect against depression. This study aims to investigate the longitudinal relationship between future self-continuity and depression among college students, and to explore the mediating role of the presence of meaning and the moderating role of perceived social support.

METHODS

We conducted two studies in China in 2022 and 2023. Study 1 was a longitudinal cross-lagged study that examined the relationship between future self-continuity and depression among 173 participants (49.13% females, Mage  = 19.39, SD = 1.63). Study 2 was a cross-sectional study that explored the mediating role of the presence of meaning and the moderating role of perceived social support among 426 participants (48.59% females, Mage  = 19.30, SD = 1.60).

RESULTS

Study 1 showed that future self-continuity (T1) could significantly predict depression (T2), but depression (T1) could not predict future self-continuity (T2). Study 2 showed that after controlling for gender, the presence of meaning mediated the relationship between future self-continuity and depression, whereas perceived social support moderated the first half of the mediated model's pathway and the direct pathway.

CONCLUSIONS

These findings suggest that enhancing the future self-continuity of college students and increasing the level of presence of meaning are effective measures for alleviating depression. Meanwhile, educators and families are called upon to provide more social support to college students.

The Effects of Social Rank and Neighborhood and School Environment on Adolescent Depression and Suicidal Ideation: A Structural Equation Modeling Approach

Depression and suicide constitute major public health problems, and their prevalence has been increasing among adolescents in the United States. More research is needed to understand the association between multilevel risk factors and depression and suicidal ideation in adolescents, particularly factors related to perceived social rank and environmental stress. The present study examined relationships among family mental history of mental illness, in-utero and perinatal complications, social rank factors, environmental factors, and depression and suicidal ideation in the past month in a clinical population of adolescents. A cross-sectional survey was administered in outpatient clinics to 197 adolescents ages 12-18 who were primarily Black and female. Findings from structural equation modeling showed the largest effects for the social rank factor on depression and suicidal ideation in the past month. These findings highlight the importance of preventive interventions for coping with social hierarchies to prevent depression and suicidal ideation.

Family therapy for adolescents with depression and suicidal ideation: A systematic review and meta-analysis

OBJECTIVE

To systematically review and meta-analyze the effectiveness of family therapy compared to other active treatments for adolescents with depressive disorders or suicidal ideation.

METHOD

We conducted a systematic search of The Cochrane Central Register of Controlled Trials, Medline, Embase, PsycINFO, AMED, CINAHL and Web of Science and performed two meta-analyses of outcomes for depressive symptoms and suicidal ideation.

RESULTS

We screened 5,940 records and identified 10 randomized controlled studies of family therapy for depressive disorder or suicidal ideation in adolescents with an active treatment comparison group. Nine studies reported outcome measures of depressive symptoms and four reported outcome measures of suicidal ideation. The meta-analysis showed no significant difference between family therapy and active comparison treatments for end-of-treatment levels of depression. For suicidal ideation our meta-analysis showed a significant effect in favour of family therapy over comparison treatments for suicidal ideation.

CONCLUSIONS

Based on the current body of research, we found that family therapy is not superior to other psychotherapies in the treatment of depressive disorder. However, family therapy leads to significantly improved outcomes for suicidal ideation, compared to other psychotherapies. The evidence for the treatment of depression is of low quality needs more research.

Is a Genetic Diathesis for Poor Nutrition Becoming More Crucial Due to the Uniformity of COVID Social Stress?

The important role of nutrition in proper neural functioning and mental health has seen wider acceptance, but is still sadly under recognized given the existent body of research. This Special Issue was designed to unite authoritative information on this topic in one volume. This editorial provides an overview of the issue, and suggests that the combination of social isolation, lack of exercise, and remaining indoors that overtook industrialized societies during 2020 are specific factors expected to change the Gene × Environment interactions for anxiety and depression. Importantly, the recent environmental changes may make biological diatheses for nutritional deficiencies even more problematic. The concept of G × E interaction is dissected to clarify a non-intuitive scenario: heritability may increase, even when a sharp increase in prevalence is entirely the result of an environmental change (e.g., COVID anxiety and isolation). Key research is highlighted, specific genetic examples are noted, and theoretical implications regarding natural selection are discussed.

A genetically informed Registered Report on adverse childhood experiences and mental health

Children who experience adversities have an elevated risk of mental health problems. However, the extent to which adverse childhood experiences (ACEs) cause mental health problems remains unclear, as previous associations may partly reflect genetic confounding. In this Registered Report, we used DNA from 11,407 children from the United Kingdom and the United States to investigate gene-environment correlations and genetic confounding of the associations between ACEs and mental health. Regarding gene-environment correlations, children with higher polygenic scores for mental health problems had a small increase in odds of ACEs. Regarding genetic confounding, elevated risk of mental health problems in children exposed to ACEs was at least partially due to pre-existing genetic risk. However, some ACEs (such as childhood maltreatment and parental mental illness) remained associated with mental health problems independent of genetic confounding. These findings suggest that interventions addressing heritable psychiatric vulnerabilities in children exposed to ACEs may help reduce their risk of mental health problems.

Relationship between adverse childhood experiences and symptom severity in adult men with Tourette Syndrome

Childhood adversity is associated with the development or expression of many neuropsychiatric disorders, including those with strong genetic underpinnings. Despite reported associations between perceived stress and tic severity, the relationship between potentially traumatic events in childhood and Tourette Syndrome (TS), a highly heritable neuropsychiatric disorder, is unknown. This study aimed to assess whether exposure to eight categories of adverse childhood experiences (ACEs) is associated with TS severity and impairment, and whether TS genetic risk modifies this association. Online survey data were collected from 351 adult males with TS who previously participated in genetic studies. Participants completed the ACE questionnaire and a lifetime version of the Yale Global Tic Severity Scale (YGTSS). Demographic and relevant health data were assessed; polygenic risk scores (PRS) measuring aggregated TS genetic risk were derived using genome-wide association data. Univariable and multivariable linear regressions examined the relationships between childhood adversity and retrospectively recalled worst-ever tic severity and impairment, adjusting for covariates. Potential gene-by-environment (GxE) interactions between ACE and PRS were estimated. After covariate adjustment, there was a significant graded dose-response relationship between ACE Scores and increases in lifetime worst-ever tic severity and impairment. There was some evidence that TS genetic risk moderated the relationship between ACE Score and tic impairment, but not tic severity, particularly for individuals with higher TS polygenic risk. We provide evidence that childhood adversity is associated with higher lifetime TS severity and impairment, although future longitudinal studies with genetically-sensitive designs are needed to determine whether these relationships are causal and/or directional.

Emotional self-regulation, impulsivity, 5-HTTLPR and tobacco use behavior among psychiatric inpatients

BACKGROUND

While the serotonin transporter (SLC6A4) gene, 5-HTTLPR, interacts with the social environment to influence both emotional self-regulation and smoking behavior, less is known about interactions between emotional self-regulation and 5-HTTLPR or their joint influence on tobacco use. Here, we examined such interactions among psychiatric inpatients, the population with the highest rates of smoking.

METHODS

Participants (506 adults) were psychiatric inpatients at The Menninger Clinic in Houston TX between 2012 and 16. Most were white (89%), male (55%), with a mean age of 32.3 years. Participants completed the Difficulties in Emotional Regulation Scale (DERS) at admission. We examined interactions with smoking among three DERS subscales and 5-HTTLPR, controlling for sex, race and age.

RESULTS

Smoking rates were higher among those with the 5-HTTPLR L'L' genotype compared to peers carrying an S' allele (47.9% vs. 37.4%, respectively). Among S' allele carrying participants, impulse control difficulties (OR = 1.09; 95%CI: 1.03-1.14) and lack of emotion clarity (OR = 1.06; 95%CI: 1.00-1.11) increased risk for ever using tobacco, while accessing more ways to regulate emotion (OR = 0.95; 95%CI: 0.92-0.99) offered a protective effect against ever using tobacco. Neither demographic nor DERS covariates were associated with using tobacco among the L'L' group.

LIMITATIONS

This ethnically homogenous sample limits generalizability and using a binary outcome can over-estimate a gene environment interaction effect.

CONCLUSIONS

Emotional self-regulation exerts a stronger influence on using tobacco among carriers of an S' allele of 5-HTTLPR than peers with the L'L' genotype. Promoting emotional self-regulatory skills may have benefits for preventing tobacco use.

The effect of environment on cross-sensitization between methylphenidate and amphetamine in female rats

Methylphenidate (MPD) and amphetamine (AMP) are both psychostimulants that are often used to treat behavioral disorders. More recently, it has also been increasingly used illicitly for recreation as well as to improve intellectual performance. Many factors such as age, gender, genetic background, and environment govern the development of behavioral sensitization to MPD and cross-sensitization with other drugs, which are experimental behavioral markers indicating potential of substance dependence and abuse. This study examines the effects of the environment and age when MPD was exposed in adulthood alone as well as in adolescence into adulthood on cross-sensitization with AMP in female SD rats by randomizing animals to either receive the drug in a home cage or a test cage during adolescence, adulthood, or both. In a 34 day experiment, 16 groups of animals starting in adolescence were treated with saline on experimental day one (ED1), followed by a 6 day (ED2-ED7) treatment with either saline, 0.6 mg/kg AMP, 0.6, 2.5, or 10.0 mg/kg MPD. Experimental groups were then subject to a 3-day washout period (ED8-ED10) and then a retreatment with the respective drug on ED11 in adolescence (P-38 to P-49). Experiments continued in the same animal groups now in adulthood (P-60) with a saline treatment (ED1), followed by the same sequence of treatments in adolescence (ED2-ED11;P-61 to P-69). A rechallenge with the same AMP or MPD dose was performed on ED11 (P-70) followed by a single exposure to 0.6 mg/kg AMP on ED12 (P-71) to assess for cross sensitization between MPD and AMP. Animals treated with MPD in both adolescence and adulthood and in the last experimental day of AMP (ED12) showed higher intensity of cross-sensitivity between MPD and AMP as compared to animals treated with MPD only in adulthood. AMP and MPD treatment in adolescence and into adulthood in the home or test cage resulted in significantly higher responses to the drug as compared to those treated only in adulthood. Overall, we conclude that environmental alteration and adolescent exposure to MPD appeared to increase the risk of cross-sensitization to AMP in female SD rats i.e, using MPD in adolescence may increase the probability of becoming dependent on drugs of abuse. This further indicates that age, sex, and environment all influence the response to MPD and AMP, and further work is needed to elucidate the risks associated with MPD and AMP use.

Gene-Environment Interactions in Vitamin D Status and Sun Exposure: A Systematic Review with Recommendations for Future Research

Vitamin D is essential for good health. Dermal vitamin D production is dependent on environmental factors such as season and latitude, and personal factors such as time spent outdoors and genetics. Varying heritability of vitamin D status by season has been reported, suggesting that gene-environment interactions (GxE) may play a key role. Thus, understanding GxE might significantly improve our understanding of determinants of vitamin D status. The objective of this review was to survey the existing methods in GxE on vitamin D studies and report on GxE effect estimates. We searched the Embase, Medline (Ovid), and Web of Science (Core Collection) databases. We included only primary research that reported on GxE effects on vitamin D status using 25-hydroxyvitamin D as a biomarker. Sun exposure was the only environmental exposure identified in these studies. The quality assessment followed the Newcastle–Ottawa Scale for cohort studies. Seven studies were included in the final narrative synthesis. We evaluate the limitations and findings of the available GxE in vitamin D research and provide recommendations for future GxE research. The systematic review was registered on PROSPERO (CRD42021238081).

Predicting Alcohol Use From Genome-Wide Polygenic Scores, Environmental Factors, and Their Interactions in Young Adulthood

OBJECTIVE

Alcohol use during emerging adulthood is associated with adverse life outcomes, but its risk factors are not well known. Here, we predicted alcohol use in 3153 young adults aged 22 years from a) genome-wide polygenic scores (GPS) based on genome-wide association studies for the target phenotypes number of drinks per week and Alcohol Use Disorders Identification Test scores, b) 30 environmental factors, and c) their interactions (i.e., G × E effects).

METHODS

Data were collected from 1994 to 2018 as a part of the UK Twins Early Development Study.

RESULTS

GPS accounted for up to 1.9% of the variance in alcohol use (i.e., Alcohol Use Disorders Identification Test score), whereas the 30 measures of environmental factors together accounted for 21.1%. The 30 GPS by environment interactions did not explain any additional variance, and none of the interaction terms exceeded the significance threshold after correcting for multiple testing.

CONCLUSIONS

GPS and some environmental factors significantly predicted alcohol use in young adulthood, but we observed no GPS by environment interactions in our study.

Sensitive period-regulating genetic pathways and exposure to adversity shape risk for depression

Animal and human studies have documented the existence of developmental windows (or sensitive periods) when experience can have lasting effects on brain structure or function, behavior, and disease. Although sensitive periods for depression likely arise through a complex interplay of genes and experience, this possibility has not yet been explored in humans. We examined the effect of genetic pathways regulating sensitive periods, alone and in interaction with common childhood adversities, on depression risk. Guided by a translational approach, we: (1) performed association analyses of three gene sets (60 genes) shown in animal studies to regulate sensitive periods using summary data from a genome-wide association study of depression (n = 807,553); (2) evaluated the developmental expression patterns of these genes using data from BrainSpan (n = 31), a transcriptional atlas of postmortem brain samples; and (3) tested gene-by-development interplay (dGxE) by analyzing the combined effect of common variants in sensitive period genes and time-varying exposure to two types of childhood adversity within a population-based birth cohort (n = 6254). The gene set regulating sensitive period opening associated with increased depression risk. Notably, 6 of the 15 genes in this set showed developmentally regulated gene-level expression. We also identified a statistical interaction between caregiver physical or emotional abuse during ages 1-5 years and genetic risk for depression conferred by the opening genes. Genes involved in regulating sensitive periods are differentially expressed across the life course and may be implicated in depression vulnerability. Our findings about gene-by-development interplay motivate further research in large, more diverse samples to further unravel the complexity of depression etiology through a sensitive period lens.

Social Capital and Depressive Episodes: Gender Differences in the ELSA-Brasil Cohort

Introduction: The association between social capital and depression is a frequent research topic in developed countries, often with inconclusive results. Furthermore, for both social capital and depression, there are gender differences established in the literature. This study investigates gender differences in the association of social capital with the incidence and maintenance of depressive episodes.

Methods: Baseline and second wave data (4 years of follow-up) from the Longitudinal Study of Adult Health (ELSA-Brasil), a multicenter cohort of civil servants with 15,105 workers aged 35–74 years, were used. Social capital was assessed using the Resource Generator, a scale composed of two different dimensions: “social support” and “prestige and education.” Depressive episodes were assessed using the Clinical Interview Schedule - Revised (CIS-R). The statistical analysis was performed using multinomial regression with adjustments for possible confounding factors.

Results: Among men, low social capital in the “social support” dimension was associated with the incidence of depressive episodes (RR = 1.66; 95% CI: 1.01–2.72). Among women, social support was associated with the maintenance of depressive episodes (RR = 2.66; 95% CI: 1.61–4.41). Social capital was not associated with the incidence or maintenance of depressive episodes in the “prestige and education” dimension in both genders.

Conclusion: The results highlight the importance of the dimension “social support” in both genders in its association with mental health. The resource-based social capital approach proved to be adequate for investigating mental health and confirms the idea that social networks can be useful in the treatment and prevention of depressive episodes.

Polygenic Risk for Major Depression Interacts with Parental Criticism in Predicting Adolescent Depressive Symptom Development

Research has focused more and more on the interplay between genetics and environment in predicting different forms of psychopathology, including depressive symptoms. While the polygenic nature of depressive symptoms is increasingly recognized, only few studies have applied a polygenic approach in gene-by-environment interaction (G × E) studies. Furthermore, longitudinal G × E studies on developmental psychopathological properties of depression are scarce. Therefore, this 6-year longitudinal community study examined the interaction between genetic risk for major depression and a multi-informant longitudinal index of critical parenting in relation to depressive symptom development from early to late adolescence. The sample consisted of 327 Dutch adolescents of European descent (56% boys; M_age T₁ = 13.00, SD_age T₁ = 0.44). Polygenic risk for major depression was based on the Hyde et al. (Nature Genetics, 48, 1031–1036, 2016) meta-analysis and genetic sensitivity analyses were based on the 23andMe discovery dataset. Latent Growth Models suggested that polygenic risk score for major depression was associated with higher depressive symptoms across adolescence (significant main effect), particularly for those experiencing elevated levels of critical parenting (significant G × E). These findings highlight how polygenic risk for major depression in combination with a general environmental factor impacts depressive symptom development from early to late adolescence.

Intergenerational transmission: Theoretical and methodological issues and an introduction to four Dutch cohorts

Behaviors, traits and characteristics are transmitted from parents to offspring because of complex genetic and non-genetic processes. We review genetic and non-genetic mechanisms of intergenerational transmission of psychopathology and parenting and focus on recent methodological advances in disentangling genetic and non-genetic factors. In light of this review, we propose that future studies on intergenerational transmission should aim to disentangle genetic and non-genetic transmission, take a long-term longitudinal perspective, and focus on paternal and maternal intergenerational transmission. We present four large longitudinal cohort studies within the Consortium on Individual Development, which together address many of these methodological challenges. These four cohort studies aim to examine the extent to which genetic and non-genetic transmission from the parental generation shapes parenting behavior and psychopathology in the next generation, as well as the extent to which self-regulation and social competence mediate this transmission. Conjointly, these four cohorts provide a comprehensive approach to the study of intergenerational transmission.

Social support and unsupportive interactions in relation to depressive symptoms: Implication of gender and the BDNF polymorphism

Reduced levels of brain derived neurotrophic factor (BDNF), through its role in neurogenesis and neuroplasticity, may be involved in the evolution and maintenance of depression. Depression has also been tied to fewer social relationships, which can vary by gender. Thus, we assessed whether the functional single nucleotide polymorphism (SNP) on the BDNF gene, Val66Met, moderated the relationship between depressive symptoms and perceived social support and unsupportive relationships, and whether these associations differed by gender. Among 945 students, (n = 667 females; n= 278 males), depressive scores were inversely related to social support, and positively related with unsupportive relations. Females reported greater social support and depressive scores compared to males. A3-way interaction was found between unsupportive relations, the Val66Met SNP, and gender, such that irrespective of genotype, females displayed astrong relationship between unsupport and depressive scores. Male Met carriers displayed this relationship, but this was less apparent among males with the Val/Val genotype. The Val66Met SNP did not moderate the link between support and depressive scores. This BDNF SNP may serve to moderate the links between psychosocial factors and depressive symptoms, but such links are nuanced, being gender-dependent and varying with the nature of the social interactions experienced.

Environmental risk factors for liver cancer and nonalcoholic fatty liver disease

Purpose of review

The objective of this review was to summarize recent epidemiologic research examining the associations between environmental exposures and liver cancer and nonalcoholic fatty liver disease (NAFLD).

Recent findings

There were 28 liver cancer studies showing positive associations for exposures to aflatoxin, air pollution, polycyclic aromatic hydrocarbons, asbestos, chimney sweeping occupation, and paints; an inverse association for ultraviolet radiation; and null/inconsistent results for organic solvents, pesticides, perfluorooctanoic acid, nuclear radiation, iron foundry occupation, and brick kiln pollution. There were n=5 NAFLD studies showing positive associations for heavy metals, methyl tertiary-butyl ether, and selenium; and no association with trihalomethanes.

Summary

Evidence suggests that particular environmental exposures may be associated with liver cancer and NAFLD. Future liver cancer studies should examine specific histological subtypes and assess historical environmental exposures. Future NAFLD research should examine incident, biopsy-confirmed cases and the potential role of obesity and/or diabetes in studies of environmental factors and NAFLD.

Genome-wide gene-environment interaction in depression: A systematic evaluation of candidate genes: The childhood trauma working-group of PGC-MDD

Gene by environment (GxE) interaction studies have investigated the influence of a number of candidate genes and variants for major depressive disorder (MDD) on the association between childhood trauma and MDD. Most of these studies are hypothesis driven and investigate only a limited number of SNPs in relevant pathways using differing methodological approaches. Here (1) we identified 27 genes and 268 SNPs previously associated with MDD or with GxE interaction in MDD and (2) analyzed their impact on GxE in MDD using a common approach in 3944 subjects of European ancestry from the Psychiatric Genomics Consortium who had completed the Childhood Trauma Questionnaire. (3) We subsequently used the genome-wide SNP data for a genome-wide case-control GxE model and GxE case-only analyses testing for an enrichment of associated SNPs. No genome-wide significant hits and no consistency among the signals of the different analytic approaches could be observed. This is the largest study for systematic GxE interaction analysis in MDD in subjects of European ancestry to date. Most of the known candidate genes/variants could not be supported. Thus, their impact on GxE interaction in MDD may be questionable. Our results underscore the need for larger samples, more extensive assessment of environmental exposures, and greater efforts to investigate new methodological approaches in GxE models for MDD.

Gene-based interaction analysis shows GABAergic genes interacting with parenting in adolescent depressive symptoms

BACKGROUND

Most gene-environment interaction studies (G × E) have focused on single candidate genes. This approach is criticized for its expectations of large effect sizes and occurrence of spurious results. We describe an approach that accounts for the polygenic nature of most psychiatric phenotypes and reduces the risk of false-positive findings. We apply this method focusing on the role of perceived parental support, psychological control, and harsh punishment in depressive symptoms in adolescence.

METHODS

Analyses were conducted on 982 adolescents of Caucasian origin (M_age (SD) = 13.78 (.94) years) genotyped for 4,947 SNPs in 263 genes, selected based on a literature survey. The Leuven Adolescent Perceived Parenting Scale (LAPPS) and the Parental Behavior Scale (PBS) were used to assess perceived parental psychological control, harsh punishment, and support. The Center for Epidemiologic Studies Depression Scale (CES-D) was the outcome. We used gene-based testing taking into account linkage disequilibrium to identify genes containing SNPs exhibiting an interaction with environmental factors yielding a p-value per single gene. Significant results at the corrected p-value of p < 1.90 × 10^-4 were examined in an independent replication sample of Dutch adolescents (N = 1354).

RESULTS

Two genes showed evidence for interaction with perceived support: GABRR1 (p = 4.62 × 10^-5 ) and GABRR2 (p = 9.05 × 10^-6 ). No genes interacted significantly with psychological control or harsh punishment. Gene-based analysis was unable to confirm the interaction of GABRR1 or GABRR2 with support in the replication sample. However, for GABRR2, but not GABRR1, the correlation of the estimates between the two datasets was significant (r (46) = .32; p = .027) and a gene-based analysis of the combined datasets supported GABRR2 × support interaction (p = 1.63 × 10^-4 ).

CONCLUSIONS

We present a gene-based method for gene-environment interactions in a polygenic context and show that genes interact differently with particular aspects of parenting. This accentuates the importance of polygenic approaches and the need to accurately assess environmental exposure in G × E.

Cortisol reactivity to stress among youth: stability over time and genetic variants for stress sensitivity

Stress sensitivity may be one process that can explain why some genetically at-risk individuals are more susceptible to some types of stress-reactive psychopathologies. Dysregulation of the limbic-hypothalamic-pituitary-adrenal (LHPA) axis, including cortisol reactivity to challenge, represents a key aspect of stress sensitivity. However, the degree of stability over time among youth, especially differential stability as a function of particular genetic variants, has not been investigated. A general community sample of children and adolescents (mean age = 11.4; 56% girls) provided a DNA sample and completed 2 separate laboratory stress challenges, across an 18-month follow-up (N = 224 at Time 1; N = 194 at Time 2), with repeated measures of salivary cortisol. Results showed that test-retest stability for several indices of cortisol reactivity across the laboratory challenge visits were significant and of moderate magnitude for the whole sample. Moreover, gene variants of several biologically plausible systems relevant for stress sensitivity (especially 5-HTTLPR and CRHR1) demonstrated differential stability of cortisol reactivity over 18-months, such that carriers of genotypes conferring enhanced environmental susceptibility exhibited greater stability of cortisol levels over time for some LHPA axis indices. Findings suggest that LHPA axis dysregulation may exhibit some trait-like aspects underlying stress sensitivity in youth, especially for those who carry genes related to greater genetic susceptibility to environmental stress.

Future Directions in Sleep and Developmental Psychopathology

It is critical for psychologists to gain a better understanding about the intersection between sleep and developmental psychopathology. However, while many strive to answer the question of whether sleep causes developmental psychopathology, or vice versa, ultimately the relationship between sleep and developmental psychopathology is complex and dynamic. This article considers future directions in the field of clinical child and adolescent psychology that go beyond this mechanistic question, highlighting areas important to address for clinicians and researchers who strive to better understand how best to serve children and adolescents with developmental psychopathology. Questions are presented about what is normal in terms of sleep across development, the role of individual variability in terms of sleep needs and vulnerability to sleep loss, and how sleep may serve as a risk or resilience factor for developmental psychopathology, concluding with considerations for interventions.

Harsh Parenting and Serotonin Transporter and BDNF Val66Met Polymorphisms as Predictors of Adolescent Depressive Symptoms

Depressive symptoms are prevalent and rise during adolescence. The present study is a prospective investigation of environmental and genetic factors that contribute to the growth in depressive symptoms and the frequency of heightened symptoms during adolescence. Participants included 206 mother-father-adolescent triads (M age at Time 1 = 13.06 years, SD = .51, 52% female). Harsh parenting was observationally assessed during a family conflict paradigm. DNA was extracted from saliva samples and genotyped for the 5-HTTLPR and BDNF Val66Met polymorphisms. Adolescents provide self-reports of depressive symptoms annually across early adolescence. The results reveal Gene × Environment interactions as predictors of adolescent depressive symptom trajectories in the context of harsh parenting as an environmental risk factor. A BDNF Val66Met × Harsh Parenting interaction predicted the rise in depressive symptoms across a 3-year period, whereas a 5-HTTLPR × Harsh Parenting interaction predicted greater frequency in elevated depressive symptoms. The findings highlight the importance of unique genetic and environmental influences in the development and course of heightened depressive symptoms during adolescence.

Detection of gene-environment interaction in pedigree data using genome-wide genotypes

Heritability may be estimated using phenotypic data collected in relatives or in distantly related individuals using genome-wide single nucleotide polymorphism (SNP) data. We combined these approaches by re-parameterizing the model proposed by Zaitlen et al and extended this model to include moderation of (total and SNP-based) genetic and environmental variance components by a measured moderator. By means of data simulation, we demonstrated that the type 1 error rates of the proposed test are correct and parameter estimates are accurate. As an application, we considered the moderation by age or year of birth of variance components associated with body mass index (BMI), height, attention problems (AP), and symptoms of anxiety and depression. The genetic variance of BMI was found to increase with age, but the environmental variance displayed a greater increase with age, resulting in a proportional decrease of the heritability of BMI. Environmental variance of height increased with year of birth. The environmental variance of AP increased with age. These results illustrate the assessment of moderation of environmental and genetic effects, when estimating heritability from combined SNP and family data. The assessment of moderation of genetic and environmental variance will enhance our understanding of the genetic architecture of complex traits.

Gene-environment interactions in psychopathology throughout early childhood: a systematic review

Up to 20% of children and adolescents worldwide suffer from mental health problems. Epidemiological studies have shown that some of these problems are already present at an early age. The recognition that psychopathology is a result of an interaction between individual experiences and genetic characteristics has led to an increase in the number of studies using a gene-environment approach (G×E). However, to date, there has been no systematic review of G×E studies on psychopathology in the first 6 years of life. Following a literature search and a selection process, 14 studies were identified and most (n=12) of the studies found at least one significant G×E effect. This review provides a systematic characterization of the published G×E studies, providing insights into the neurobiological and environmental determinants involved in the etiology of children's psychopathology.

GENOME-WIDE ASSOCIATION STUDY (GWAS) AND GENOME-WIDE BY ENVIRONMENT INTERACTION STUDY (GWEIS) OF DEPRESSIVE SYMPTOMS IN AFRICAN AMERICAN AND HISPANIC/LATINA WOMEN

BACKGROUND

Genome-wide association studies (GWAS) have made little progress in identifying variants linked to depression. We hypothesized that examining depressive symptoms and considering gene-environment interaction (GxE) might improve efficiency for gene discovery. We therefore conducted a GWAS and genome-wide by environment interaction study (GWEIS) of depressive symptoms.

METHODS

Using data from the SHARe cohort of the Women's Health Initiative, comprising African Americans (n = 7,179) and Hispanics/Latinas (n = 3,138), we examined genetic main effects and GxE with stressful life events and social support. We also conducted a heritability analysis using genome-wide complex trait analysis (GCTA). Replication was attempted in four independent cohorts.

RESULTS

No SNPs achieved genome-wide significance for main effects in either discovery sample. The top signals in African Americans were rs73531535 (located 20 kb from GPR139, P = 5.75 × 10(-8) ) and rs75407252 (intronic to CACNA2D3, P = 6.99 × 10(-7) ). In Hispanics/Latinas, the top signals were rs2532087 (located 27 kb from CD38, P = 2.44 × 10(-7) ) and rs4542757 (intronic to DCC, P = 7.31 × 10(-7) ). In the GEWIS with stressful life events, one interaction signal was genome-wide significant in African Americans (rs4652467; P = 4.10 × 10(-10) ; located 14 kb from CEP350). This interaction was not observed in a smaller replication cohort. Although heritability estimates for depressive symptoms and stressful life events were each less than 10%, they were strongly genetically correlated (rG = 0.95), suggesting that common variation underlying self-reported depressive symptoms and stressful life event exposure, though modest on their own, were highly overlapping in this sample.

CONCLUSIONS

Our results underscore the need for larger samples, more GEWIS, and greater investigation into genetic and environmental determinants of depressive symptoms in minorities.

FKBP5 polymorphisms moderate the influence of adverse life events on the risk of anxiety and depressive disorders in preschool children

FKBP5 is thought to be involved in the pathogenesis of stress-related disorders. Studies have shown that FKBP5 genotypes moderate the risk of post-traumatic stress disorder and depression in traumatized adults. We aimed to replicate this finding in a sample of preschool children. Parents of preschoolers (N = 186) were interviewed using the Preschool Age Psychiatric Assessment (PAPA) to evaluate the presence of anxiety and depressive disorders and to quantify the child's exposure to adverse events. All FKBP5 polymorphisms showed significant interactions with mild to moderate life events, but not with severe life events, in predicting the risk of anxiety and/or depressive disorders (p = 0.003-0.019). Children who experienced a high number of mild to moderate life events had a higher risk of developing an anxiety and/or depressive disorder if they were carriers of the minor allele compared to major allele homozygotes. Results indicate that genetic variation in FKBP5 influences the risk of anxiety and/or depressive disorders in preschool age by altering the sensitivity to the deleterious effects of mild to moderate adverse events. In case of severe life events, the FKBP5 genotype does not seem to play a role, suggesting that severe life events might influence directly the risk of anxiety and/or depressive disorders independent of an FKBP5 genotype-dependent vulnerability.

The Genetics of Stress-Related Disorders: PTSD, Depression, and Anxiety Disorders

Research into the causes of psychopathology has largely focused on two broad etiologic factors: genetic vulnerability and environmental stressors. An important role for familial/heritable factors in the etiology of a broad range of psychiatric disorders was established well before the modern era of genomic research. This review focuses on the genetic basis of three disorder categories-posttraumatic stress disorder (PTSD), major depressive disorder (MDD), and the anxiety disorders-for which environmental stressors and stress responses are understood to be central to pathogenesis. Each of these disorders aggregates in families and is moderately heritable. More recently, molecular genetic approaches, including genome-wide studies of genetic variation, have been applied to identify specific risk variants. In this review, I summarize evidence for genetic contributions to PTSD, MDD, and the anxiety disorders including genetic epidemiology, the role of common genetic variation, the role of rare and structural variation, and the role of gene-environment interaction. Available data suggest that stress-related disorders are highly complex and polygenic and, despite substantial progress in other areas of psychiatric genetics, few risk loci have been identified for these disorders. Progress in this area will likely require analysis of much larger sample sizes than have been reported to date. The phenotypic complexity and genetic overlap among these disorders present further challenges. The review concludes with a discussion of prospects for clinical translation of genetic findings and future directions for research.

The Involvement of Genes in Adolescent Depression: A Systematic Review

Numerous studies have reported on the roles of genetic factors in the development of depression in adolescents and young adults. However, there are few systematic reviews that update our understanding of adolescent depression with the biological findings identifying the roles of gene expression and/or polymorphism(s). This review systematically summarized the findings that clearly identified the contribution of a gene to the risk of depression in adolescents between the ages of 10 and 19 years old and young adults between the ages of 20 and 25 years old. Data were obtained through searching PubMed, Embase, and Web of Science. A total of 47 studies on early adolescence and three studies on young adults were included in the current review. Most articles studied genes in the serotonergic system (n = 26), dopaminergic system (n = 3), and the Brain-derived neurotropic factor (BDNF) gene (n = 12). 92.3% of studies (24/26) identified positive associations of 5-HTTLPR polymorphism with depressive illness or depressive symptoms. 83.3% of studies (10/12) found positive association between BDNF Val66Met genotype and adolescent depressive symptoms. More studies should be conducted on the 18 genes reported in a few studies to clarify their roles in the risk for adolescent depression.

The BDNF Val66Met Polymorphism Interacts with Maternal Parenting Influencing Adolescent Depressive Symptoms: Evidence of Differential Susceptibility Model

Although depressive symptoms are common during adolescence, little research has examined gene-environment interaction on youth depression. This study chose the brain-derived neurotrophic factor (BDNF) gene, tested the interaction between a functional polymorphism resulting amino acid substitution of valine (Val) to methionine (Met) in the proBDNF protein at codon 66 (Val66Met), and maternal parenting on youth depressive symptoms in a sample of 780 community adolescents of Chinese Han ethnicity (aged 11-17, M = 13.6, 51.3 % females). Participants reported their depressive symptoms and perceived maternal parenting. Results indicated the BDNF Val66Met polymorphism significantly moderated the influence of maternal warmth-reasoning, but not harshness-hostility, on youth depressive symptoms. Confirmatory model evaluation indicated that the interaction effect involving warmth-reasoning conformed to the differential-susceptibility rather than diathesis-stress model of person-X-environment interaction. Thus, Val carriers experienced less depressive symptoms than Met homozygotes when mothering was more positive but more symptoms when mothering was less positive. The findings provided evidence in support of the differential susceptibility hypothesis of youth depressive symptoms and shed light on the importance of examining the gene-environment interaction from a developmental perspective.

Interleukin 1B gene (IL1B) variation and internalizing symptoms in maltreated preschoolers

Evidence now implicates inflammatory proteins in the neurobiology of internalizing disorders. Genetic factors may influence individual responses to maltreatment; however, little work has examined inflammatory genetic variants in adults and none in children. The present study examined the role of an interleukin 1B gene (IL1B) variant in preschoolers exposed to maltreatment and other forms of adversity in internalizing symptom development. One hundred ninety-eight families were enrolled, with one child (age 3-5 years) from each family. Adversity measures included child protective service documentation of moderate-severe maltreatment in the last 6 months and interview-assessed contextual stressors. Internalizing symptoms were measured using the Child Behavior Checklist and the Diagnostic Infant and Preschool Assessment. Maltreated children had higher major depressive disorder (MDD) and posttraumatic stress disorder symptoms and marginally higher internalizing symptoms on the Child Behavior Checklist. Controlling for age, sex, and race, IL1B genotype was associated with MDD symptoms (p = .002). Contextual stressors were significantly associated with MDD and posttraumatic stress disorder and marginally with internalizing symptoms. The IL1B genotype interacted with contextual stress such that children homozygous for the minor allele had more MDD symptoms (p = .045). These results suggest that genetic variants of IL1B may modulate the development of internalizing symptoms in the face of childhood adversity.

The effects of the interplay of genetics and early environmental risk on the course of internalizing symptoms from late childhood through adolescence

Internalizing symptoms during adolescence and beyond is a major public health concern, particularly because severe symptoms can lead to the diagnosis of a number of serious psychiatric conditions. This study utilizes a unique sample with a complex statistical method in order to explore Gene × Environment interactions found in internalizing symptoms during adolescence. Data for this study were drawn from a longitudinal prevention intervention study (n = 798) of Baltimore city school children. Internalizing symptom data were collected using self-report and blood or saliva samples genotyped using Affymetrix 6.0 microarrays. A major depression polygenic score was created for each individual using information from the major depressive disorder Psychiatric Genetics Consortium and used as a predictor in a latent trait-state-occasion model. The major depressive disorder polygenic score was a significant predictor of the stable latent trait variable, which captures time-independent phenotypic variability. In addition, an early childhood stressor of death or divorce was a significant predictor of occasion-specific variables. A Gene × Environment interaction was not a significant predictor of the latent trait or occasion variables. These findings support the importance of genetics on the stable latent trait portion of internalizing symptoms across adolescence.

Genetic determinants of depression: recent findings and future directions

LEARNING OBJECTIVES

After participating in this activity, learners should be better able to: 1. Evaluate current evidence regarding the genetic determinants of depression 2. Assess findings from studies of gene-environment interaction 3. Identify challenges to gene discovery in depression Depression is one of the most prevalent, disabling, and costly mental health conditions in the United States and also worldwide. One promising avenue for preventing depression and informing its clinical treatment lies in uncovering the genetic and environmental determinants of the disorder as well as their interaction (G × E). The overarching goal of this review article is to translate recent findings from studies of genetic association and G × E related to depression, particularly for readers without in-depth knowledge of genetics or genetic methods. The review is organized into three major sections. In the first, we summarize what is currently known about the genetic determinants of depression, focusing on findings from genome-wide association studies (GWAS). In the second section, we review findings from studies of G × E, which seek to simultaneously examine the role of genes and exposure to specific environments or experiences in the etiology of depression. In the third section, we describe the challenges to genetic discovery in depression and promising strategies for future progress.

Effect of the serotonin transporter gene and of environment on the continuity of anxiety and depression traits throughout adolescence

Aims. Many studies of various stress reactive phenotypes suggest that 5-HTTLPR short allele carriers (S-carriers) are characterised by the stable trait of negative affectivity that is converted to psychopathology only under conditions of stress. In this study, we examined the moderating role of the 5-HTTLPR on the relationship between two objective chronic risk factors, i.e. socioeconomic status (SES) and family structure, and internalising symptoms across adolescence. Methods. A multigroup path analysis was employed in a general adolescent population sample of a 5-year follow-up study. Results. Internalising problems were significantly more stable in the S-carriers. The focus on the main dimensions of internalising problems, i.e. anxiety and depression, revealed two different developmental patterns. In the S-carriers Anxiety problems seemed to be more stable and to predict a possible evolution towards the development of Depressive problems. In the long allele homozygotes (LL-subjects) the anxiety trait was significantly less stable, and, in late-adolescence, seemed to be significantly predicted by SES, suggesting a possible gene-environment interaction (G × E). Family structure seemed to play a role in a G × E perspective only until early-adolescence, while during late-adolescence SES seemed to play a pivotal role in interaction with 5-HTTLPR, with the S-allele playing a protective role. Conclusions. Future models of the developmental link between environmental adversities and internalising behaviour therefore need to consider that the effect of G × E interaction, may be associated with internalising behaviour via different mechanisms during different time frames and that shifts in the strength of this effect should be expected across development.

Research review: Polygenic methods and their application to psychiatric traits

BACKGROUND

Despite evidence from twin and family studies for an important contribution of genetic factors to both childhood and adult onset psychiatric disorders, identifying robustly associated specific DNA variants has proved challenging. In the pregenomics era the genetic architecture (number, frequency and effect size of risk variants) of complex genetic disorders was unknown. Empirical evidence for the genetic architecture of psychiatric disorders is emerging from the genetic studies of the last 5 years.

METHODS AND SCOPE

We review the methods investigating the polygenic nature of complex disorders. We provide mini-guides to genomic profile (or polygenic) risk scoring and to estimation of variance (or heritability) from common SNPs; a glossary of key terms is also provided. We review results of applications of the methods to psychiatric disorders and related traits and consider how these methods inform on missing heritability, hidden heritability and still-missing heritability.

FINDINGS

Genome-wide genotyping and sequencing studies are providing evidence that psychiatric disorders are truly polygenic, that is they have a genetic architecture of many genetic variants, including risk variants that are both common and rare in the population. Sample sizes published to date are mostly underpowered to detect effect sizes of the magnitude presented by nature, and these effect sizes may be constrained by the biological validity of the diagnostic constructs.

CONCLUSIONS

Increasing the sample size for genome wide association studies of psychiatric disorders will lead to the identification of more associated genetic variants, as already found for schizophrenia. These loci provide the starting point of functional analyses that might eventually lead to new prevention and treatment options and to improved biological validity of diagnostic constructs. Polygenic analyses will contribute further to our understanding of complex genetic traits as sample sizes increase and as sample resources become richer in phenotypic descriptors, both in terms of clinical symptoms and of nongenetic risk factors.

Translating multilevel theory into multilevel research: challenges and opportunities for understanding the social determinants of psychiatric disorders

INTRODUCTION

The observation that features of the social environment, including family, school, and neighborhood characteristics, are associated with individual-level outcomes has spurred the development of dozens of multilevel or ecological theoretical frameworks in epidemiology, public health, psychology, and sociology, among other disciplines. Despite the widespread use of such theories in etiological, intervention, and policy studies, challenges remain in bridging multilevel theory and empirical research.

METHODS

This paper set out to synthesize these challenges and provide specific examples of methodological and analytical strategies researchers are using to gain a more nuanced understanding of the social determinants of psychiatric disorders, with a focus on children's mental health. To accomplish this goal, we begin by describing multilevel theories, defining their core elements, and discussing what these theories suggest is needed in empirical work. In the second part, we outline the main challenges researchers face in translating multilevel theory into research. These challenges are presented for each stage of the research process. In the third section, we describe two methods being used as alternatives to traditional multilevel modeling techniques to better bridge multilevel theory and multilevel research. These are (1) multilevel factor analysis and multilevel structural equation modeling; and (2) dynamic systems approaches.

CONCLUSIONS

Through its review of multilevel theory, assessment of existing strategies, and examination of emerging methodologies, this paper offers a framework to evaluate and guide empirical studies on the social determinants of child psychiatric disorders as well as health across the life course.

Dopamine genetic risk score predicts depressive symptoms in healthy adults and adults with depression

BACKGROUND

Depression is a common source of human disability for which etiologic insights remain limited. Although abnormalities of monoamine neurotransmission, including dopamine, are theorized to contribute to the pathophysiology of depression, evidence linking dopamine-related genes to depression has been mixed. The current study sought to address this knowledge-gap by examining whether the combined effect of dopamine polymorphisms was associated with depressive symptomatology in both healthy individuals and individuals with depression.

METHODS

Data were drawn from three independent samples: (1) a discovery sample of healthy adult participants (n = 273); (2) a replication sample of adults with depression (n = 1,267); and (3) a replication sample of healthy adult participants (n = 382). A genetic risk score was created by combining functional polymorphisms from five genes involved in synaptic dopamine availability (COMT and DAT) and dopamine receptor binding (DRD1, DRD2, DRD3).

RESULTS

In the discovery sample, the genetic risk score was associated with depressive symptomatology (β = -0.80, p = 0.003), with lower dopamine genetic risk scores (indicating lower dopaminergic neurotransmission) predicting higher levels of depression. This result was replicated with a similar genetic risk score based on imputed genetic data from adults with depression (β = -0.51, p = 0.04). Results were of similar magnitude and in the expected direction in a cohort of healthy adult participants (β = -0.86, p = 0.15).

CONCLUSIONS

Sequence variation in multiple genes regulating dopamine neurotransmission may influence depressive symptoms, in a manner that appears to be additive. Further studies are required to confirm the role of genetic variation in dopamine metabolism and depression.

The Association Between Peer and own Aggression is Moderated by the BDNF Val-met Polymorphism

Peer antisocial behavior robustly predicts adolescents' own behavior but not all adolescents are equally vulnerable to their peers' influence and genetic factors may confer vulnerability. This study used data of n = 3081 adolescents from the Avon Longitudinal Study of Parents and Children (ALSPAC) to examine whether BDNF, a polymorphism that affects psychological functioning, moderates the association between affiliation with aggressive peers at age 10 and own aggression at age 15. A significant gene-environment interaction was found, where those who affiliated with aggressive peers in childhood showed increased risk for being aggressive in adolescence if they carried the BDNF met-met variant compared to val-val carriers. Our findings underline the importance of both biological and social factors for adolescent development.