Peer Victimization and DRD4 Genotype Influence Problem Behaviors in Young Children

Examining how and why polygenic dopamine composite levels moderate adolescents' vulnerability to peer victimization

Extensive literature documents that dopaminergic genes play an important role in the link between adverse environments and adolescents' problem behavior. However, little is known about the potential mechanism underlying adolescents' vulnerability to peer victimization. The current study examined the effect of the interplay between a polygenic dopamine composite (i.e., COMT Val158Met and DRD2-141C Ins/Del polymorphisms) and peer victimization on adolescents' externalizing problems as well as the mediating role of emotion dysregulation in the interactive effects in a sample of 393 Chinese adolescents (Mean age = 14.71 years; 50.1% girls). A significant moderation of dopaminergic genetic composite was observed in girls but not in boys. In addition, emotion dysregulation partially explained the moderating effect of dopaminergic genes. Specifically, girls with genic composite indexing low dopamine activity reported a higher level of emotion dysregulation when faced with more peer victimization. More difficulties with emotion regulation, in turn, predicted more pronounced externalizing problems in girls. This study underscores polygenic underpinnings of adolescent vulnerability to negative peer experiences and suggests the importance of considering sex differences when investigating genic influence on the relationship between adverse environments and externalizing problems.

A neural model of vulnerability and resilience to stress-related disorders linked to differential susceptibility

Expert opinion remains divided concerning the impact of putative risk factors on vulnerability to depression and other stress-related disorders. A large body of literature has investigated gene by environment interactions, particularly between the serotonin transporter polymorphism (5-HTTLPR) and negative environments, on the risk for depression. However, fewer studies have simultaneously investigated the outcomes in both negative and positive environments, which could explain some of the inconclusive findings. This is embodied by the concept of differential susceptibility, i.e., the idea that certain common gene polymorphisms, prenatal factors, and traits make some individuals not only disproportionately more susceptible and responsive to negative, vulnerability-promoting environments, but also more sensitive and responsive to positive, resilience-enhancing environmental conditions. Although this concept from the field of developmental psychology is well accepted and supported by behavioral findings, it is striking that its implementation in neuropsychiatric research is limited and that underlying neural mechanisms are virtually unknown. Based on neuroimaging studies that examined how factors mediating differential susceptibility affect brain function, we posit that environmental sensitivity manifests in increased salience network activity, increased salience and default mode network connectivity, and increased salience and central executive network connectivity. These changes in network function may bring about automatic exogenous attention for positive and negative stimuli and flexible attentional set-shifting. We conclude with a call to action; unraveling the neural mechanisms through which differential susceptibility factors mediate vulnerability and resilience may lead us to personalized preventive interventions.

Are Different Individuals Sensitive to Different Environments? Individual Differences in Sensitivity to the Effects of the Parent, Peer and School Environment on Externalizing Behavior and its Genetic and Environmental Etiology

Externalizing behavior is substantially affected by genetic effects, which are moderated by environmental exposures. However, little is known about whether these moderation effects differ depending on individual characteristics, and whether moderation of environmental effects generalizes across different environmental domains. With a large sample (N = 1,441 individuals) of early adolescent twins (ages 11 and 13), using a longitudinal multi-informant design, we tested interaction effects between negative emotionality and both positive and negative aspects of three key social domains: parents, peers, and schools, on the phenotypic variance as well as the etiology of externalizing. Negative emotionality moderated some of the environmental effects on the phenotypic, genetic, and environmental variance in externalizing, with adolescents at both ends of the negative emotionality distribution showing different patterns of sensitivity to the tested environmental influences. This is the first use of gene-environment interaction twin models to test individual differences in environmental sensitivity, offering a new approach to study such effects.

Longitudinal Links between Adolescent and Peer Conduct Problems and Moderation by a Sensitivity Genetic Index

The most extensively studied influence on adolescent conduct problem behaviors is peers, and the literature points to genetics as one source of individual differences in peer influence. The purpose of this study was to test the hypothesis that an environmental sensitivity genetic index comprised of DRD4, 5-HTTLPR, and GABRA2 variation would moderate the association between peer and adolescent conduct problems. Latent growth modeling was applied to PROSPER project longitudinal data from adolescents and their peers. Results showed the hypothesis was supported; adolescents with more copies of putative sensitivity alleles were more strongly influenced by their peers. The interaction form was consistent with differential susceptibility in follow-up analyses. Strengths and weaknesses of genetic aggregates for sensitivity research are discussed.

Genotype-environment correlation by intervention effects underlying middle childhood peer rejection and associations with adolescent marijuana use

Aggressive behavior in middle childhood can contribute to peer rejection, subsequently increasing risk for substance use in adolescence. However, the quality of peer relationships a child experiences can be associated with his or her genetic predisposition, a genotype-environment correlation (rGE). In addition, recent evidence indicates that psychosocial preventive interventions can buffer genetic predispositions for negative behavior. The current study examined associations between polygenic risk for aggression, aggressive behavior, and peer rejection from 8.5 to 10.5 years, and the subsequent influence of peer rejection on marijuana use in adolescence (n = 515; 256 control, 259 intervention). Associations were examined separately in control and intervention groups for children of families who participated in a randomized controlled trial of the family-based preventive intervention, the Family Check-Up . Using time-varying effect modeling (TVEM), polygenic risk for aggression was associated with peer rejection from approximately age 8.50 to 9.50 in the control group but no associations were present in the intervention group. Subsequent analyses showed peer rejection mediated the association between polygenic risk for aggression and adolescent marijuana use in the control group. The role of rGEs in middle childhood peer processes and implications for preventive intervention programs for adolescent substance use are discussed.

ADHD symptoms across adolescence: the role of the family and school climate and the DRD4 and 5-HTTLPR genotype

We examined bidirectional relations between attention-deficit/hyperactivity disorder (ADHD) symptoms and family and school climate, and the possible role of DRD4 and/or 5-HTTLPR genotypes herein. Three-wave longitudinal data of 1860 adolescents (mean ages 11, 13.5, and 16 years) from the general population and clinic-referred cohort of TRacking Adolescents' Individual Lives Survey were used. Using a multigroup Random Intercept Cross-Lagged Panel Model, we tested between-person (i.e., stable trait levels) and within-person (i.e., causal processes) associations across ADHD symptoms, family and school climate, and the extent to which these depended on genotype. Findings indicated no influence of genotype. Results did show significant between-person differences (ADHD symptoms with family climate r = .38; and school climate r = .23, p values < .001), indicating that higher stable levels of ADHD symptoms were associated with a less favorable family and school climate. Regarding within-person causal processes, ADHD symptoms predicted a less favorable family climate in early adolescence (β = .16, p < .01), while ADHD symptoms predicted a more favorable family climate in the later phase of adolescence (β = - .11, p < .01), a finding which we explain by normative developmental changes during adolescence. Overall, this study showed that negative associations between ADHD symptoms and both family and school climate are largely explained by stable between-person differences. We recommend applying the Random Intercept Cross-Lagged Path Model to developmental data to tease stable associations and change processes apart.

The Southern Illinois Twins/Triplets and Siblings Study (SITSS): A Longitudinal Study of Early Child Development

This article reviews the Southern Illinois Twins/Triplets and Siblings Study (SITSS) and describes some of the findings related to recent projects that were completed using this sample. At this time, the SITSS has enrolled 375 twin pairs, 12 triplet families, 1 family of quadruplets, 98 nontwin sibling pairs and 287 singletons. Testing begins for twins and triplets as young as age 1 and then occurs yearly on their birthdays until 5 years of age. Through age 20, various follow-up studies have been conducted on the SITSS sample to examine their social, emotional, and cognitive development across childhood and adolescence from a behavioral genetic perspective. A variety of methodologies have been used to investigate gene-environment correlations (rGE) and gene-environment interactions (GxE). Advanced statistical procedures (e.g., genetic likelihood indices and multilevel modeling) have been utilized to further investigate genetic underpinnings of behavior. Recent results have indicated genetic influences on the aggressiveness of preschoolers' media preferences, increased problem behaviors related to young children's overestimation of self-competence, and the influence of early life temperament and internalizing problems on adolescent health behaviors. Additionally, the SITSS has provided evidence for evocative rGE for various behaviors (aggression, prosocial and play), as well as findings supporting interactions between the dopamine receptor D4 gene (DRD4) and the environment (peer victimization, prenatal birth complications and parental sensitivity). Together, by use of multitrait and multimethodological investigations, this behavior genetic data set assists in furthering our understanding of biological and environmental influences on children's development.

An exploration of common dopaminergic variants and behavior problems in siblings at high risk for autism spectrum disorder

Younger siblings of children with ASD often exhibit elevated internalizing and externalizing problems. We investigated common dopaminergic variants (DRD4 and DRD2) in relation to behavior problems at 36 months. Genotypes linked to less efficient dopaminergic functioning were associated with higher internalizing problems in high-risk siblings.

Respiratory sinus arrhythmia in the fourth decade of life depends on birth weight and the DRD4 gene: Implications for understanding the development of emotion regulation

INTRODUCTION

The long allele of the DRD4 gene can confer different behavioral and emotional phenotypes depending upon environmental exposure, although the physiological changes underlying these phenotypes are not fully known. We sought to extend this work by assessing the interaction of the DRD4 gene and exposure to perinatal adversity (indexed by extremely low birth weight [ELBW]) on resting respiratory sinus arrhythmia (RSA), a neurophysiological measure of emotion regulation, in adulthood.

METHODS

We examined the interaction between the DRD4 gene and perinatal adversity on RSA at age 30-35 in a longitudinal cohort of ELBW survivors (n = 49) and NBW controls (n = 63). Buccal DNA samples were genotyped for short and long carriers of the exon III DRD4 VNTR gene. Resting RSA was assessed by electrocardiogram.

RESULTS

We report an interaction between birth weight status and DRD4 gene (F = 9.42, p = 0.003) in predicting RSA, such that DRD4 long carriers had the highest and lowest resting RSA depending on whether they were born NBW or ELBW, respectively. DRD4 short carriers were less sensitive to birth weight. Additionally, reduced RSA was correlated with a history of major depressive disorder, suggesting it was a reliable index of emotion dysregulation.

DISCUSSION

These results suggest that the perinatal environment influences autonomic nervous system functioning in individuals with genotypes that confer additional sensitivity. Whether the long-term autonomic outcomes of this environmental sensitivity are beneficial or detrimental appears to depend on the quality of the early life environment, and may influence the development of emotion regulatory and psychiatric problems in adulthood.

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

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

Genetic Influences on Peer and Family Relationships Across Adolescent Development: Introduction to the Special Issue

Nearly all aspects of human development are influenced by genetic and environmental factors, which conjointly shape development through several gene-environment interplay mechanisms. More recently, researchers have begun to examine the influence of genetic factors on peer and family relationships across the pre-adolescent and adolescent time periods. This article introduces the special issue by providing a critical overview of behavior genetic methodology and existing research demonstrating gene-environment processes operating on the link between peer and family relationships and adolescent adjustment. The overview is followed by a summary of new research studies, which use genetically informed samples to examine how peer and family environment work together with genetic factors to influence behavioral outcomes across adolescence. The studies in this special issue provide further evidence of gene-environment interplay through innovative behavior genetic methodological approaches across international samples. Results from the quantitative models indicate environmental moderation of genetic risk for coercive adolescent-parent relationships and deviant peer affiliation. The molecular genetics studies provide support for a gene-environment interaction differential susceptibility model for dopamine regulation genes across positive and negative peer and family environments. Overall, the findings from the studies in this special issue demonstrate the importance of considering how genes and environments work in concert to shape developmental outcomes during adolescence.