Community Matters: GxE Interactions between Dopamine and Serotonin Polymorphisms and Community-Level Factors in Predicting Childhood Aggression and Violent Behavior

Background and Purpose: Youth aggression and violent behavior span a continuum ranging from bullying behavior to engaging in fights, carrying weapons, committing assault, rape, and murder.  Research demonstrates that such behavior evolves throughout development, often beginning in childhood and progressing into adulthood. Gene by environment (GxE) research into youth aggression and violent behavior has begun to explore the interaction between genotypes and societal forces, but little is known about the interaction between dopamine and serotonin polymorphisms and social control, community violence exposure, and neighborhood instability.  Even less is known about the differential susceptibility of children who possess dopamine and serotonin polymorphisms to these societal factors.  This study draws upon the bioecological framework to understand to what extent GxE interactions between dopamine and serotonin polymorphisms and community-level factors affect the susceptibility to perpetrating childhood aggression and violent behavior (CAVB) in preadolescent children.

Methods: This stratified cross-sectional study analyzed data from the Fragile Families Child Wellbeing Study. The sample included children of single mothers who answered all questions measuring the dependent variable (CAVB) and who had children who possessed six dopamine and serotonin polymorphisms (Yr 3, n=2,102; Yr 5, n=2,065; Yr 9, n=2,007).  Variables include a latent construct of CAVB measured at year nine, a latent construct of social control and indexes of community instability and violence exposure measured at years 3, 5, and 9, and two genetic indexes containing specific dopamine and serotonin polymorphisms. Data analysis consisted of confirmatory factor analysis to develop the latent variables, ANOVA, bivariate correlation, and ordinary least squares regression to test models by gender and year. Differential susceptibility was identified via tests of simple slopes and regions of significance.

Results: We identified several significant GxE interactions. Boys who possessed fewer dopamine and serotonin alleles and who were exposed to low social control (at years 3 and 5) or high community instability (at year 5) were more likely to perpetrate CAVB at year 9 than boys with more alleles. Girls who possessed fewer dopamine and serotonin alleles and were exposed to low social control at year 3 perpetrated more CAVB at year 9 than girls who possessed more alleles. Moreover, girls who possessed fewer alleles were differentially susceptible to social control; that is, when exposed to low social control they perpetrated more CAVB, and when exposed to high social control, they perpetrated less CAVB than peers who possessed more alleles. 

Conclusions/Implications: Findings support the notion that community-level factors of social control and community instability matter for children who possess specific dopamine and serotonin polymorphisms and suggest that efforts to reduce childhood aggression and violent behavior also target these societal forces.  Implications for social work include policy development that addresses the economic and social well-being of neighborhoods and the high rate of resident turnover. Doing so may mitigate the negative effects of low social control on children living in impoverished communities.  Study findings also inform gene by intervention research that examines if children with dopamine and serotonin polymorphisms respond better to community-based interventions aimed at increasing social control.