Do Associations Between Family Violence and Childhood Aggression Vary According to Polygenic Serotonergic Differences?

• In Event: Enhancing Our Understanding of Risk Factors of Socioemotional Problems Through Cutting-Edge Methodological and Biopsychosocial Approaches

Abstract

Background. Children exposed to family violence, such as child-directed and child-witnessed parental violence, tend to manifest higher levels of childhood physical aggression (CPA), as well as antisocial behaviors in adolescence and early adulthood (Braga et al., 2017; Rivenbark et al., 2018). Genetically-informed studies additionally show that individual differences in CPA are partly inherited. Finally, family environment and genetic risk have been independently and jointly linked to CPA (Lubke et al., 2018; Porsch et al., 2016). While there is a general consensus about the polygenic nature of CPA, it remains unclear whether genes (eg., serotonergic genes) moderate the impact of child-directed and child-witnessed parental violence on this phenotype. We tested two hypotheses. First, that a haplotype-based serotonergic polygenic risk score previously associated with adolescent and adulthood antisocial behaviors (Langevin et al., 2020) also predicted childhood physical aggression; Second, that this haplotype-based serotonergic polygenic risk score moderates the link between forms of family violence and CPA.

Methods. Participants were 410 male members of the Quebec Study of Kindergarten Children, for whom DNA samples were collected. Yearly teacher-rated assessments of childhood physical aggression were prospectively collected between the ages of 7 and 11 years. Child-directed and child-witnessed parental violence was self-reported using an adapted version of the Revised Conflict Tactics Scales. On average, male participants for whom DNA was not collected exhibited higher levels of disruptive behaviours in kindergarten [t(1, 528.25)=-3.70, p=.001] and were from lower socioeconomic backgrounds [t(1, 469.76)=-6.40, p=.001]. Analyses were conducted using negative binomial regressions with robust estimators and included inverse probability weighted to account for non-random attrition.

Results. Findings show that the haplotype-based serotonergic polygenic risk score predicted higher childhood physical aggression levels [β(SE)=.20(.06), p<.001]. Moreover, this serotonergic polygenic risk moderated the link between child-directed parental violence and CPA [B(SE)=.02(.00), p<.001, R2=8.0%; Figure 1]. Youths who experienced more parental violence had higher CPA levels if they were also carrying moderate or higher serotonergic genetic risk, but not lower levels. Similarly, the association between having witnessed intra-parental violence and CPA varied according to polygenic serotonergic risk [B(SE)=.06(.01), p<.001; R2=5.7%; Figure 2]. Children who witnessed higher levels of intra-parental violence manifested significantly more aggressive behaviours than their peers only if they also carried higher serotonergic genetic risk.

Conclusion. This study extends previous research in two ways. Firstly, haplotype-based polygenic risk scores appear to be a promising strategy to capture cumulative and synergic effects of genetic differences. Secondly, our results provide further support to the Diathesis-stress model, which predicts greater sensitivity to adverse environments among individuals with higher genetic risk. Our findings extend previous research indicating a genetic moderation of serotonergic genes in the association between family adversity and violence and antisocial outcomes by relying on a haplotype-based cumulative risk score and according to two subtypes of parental violence.

Authors

• Stephanie Langevin, Duke University
  Presenting Author

• Isabelle Ouellet-Morin, Université de Montréal