Time-varying Effects of GABRG1 and Maladaptive Peer Behavior on Externalizing Behavior from Childhood to Adulthood: Testing Gene × Environment × Development Effects

Abstract

Engagement in externalizing behavior is problematic. Deviant peer affiliation increases risk for externalizing behavior. Yet, peer effects vary across individuals and may differ across genes. This study determines gene × environment × development interactions as they apply to externalizing behavior from childhood to adulthood. A sample (n = 687; 68% male, 90% White) of youth from the Michigan Longitudinal Study was assessed from ages 10 to 25. Interactions between γ-amino butyric acid type A receptor γ1 subunit (GABRG1; rs7683876, rs13120165) and maladaptive peer behavior on externalizing behavior were examined using time-varying effect modeling. The findings indicate a sequential risk gradient in the influence of maladaptive peer behavior on externalizing behavior depending on the number of G alleles during childhood through adulthood. Individuals with the GG genotype are most vulnerable to maladaptive peer influences, which results in greater externalizing behavior during late childhood through early adulthood.

Keywords: Externalizing behavior; GABRG1; Genes; Peers; TVEM.

Figure 1.

Michigan Longitudinal Study Assessment Schedule Note. Assessments were conducted every three years beginning when the target child was 3 to 5 years of age. T = three-year intervals. Annual assessments were also conducted during late childhood. A = annual assessments. The current study focuses on assessments contained within the box.

Figure 2.

Time-varying effect model for peer delinquency on externalizing behavior Note. GABRG1 rs7683876 effects depicted. Solid lines represent trajectories, while the dotted lines represent the 95% confidence intervals. Values above the line represent positive associations. Values below the blue line represent negative associations. Confidence intervals that include the blue line are not significant. The y-axes represent estimated effects across time.

Figure 3.

Time-varying effect model for peer substance use on externalizing behavior Note. GABRG1 rs7683876 effects depicted. Solid lines represent trajectories, while the dotted lines represent the 95% confidence intervals. Values above the line represent positive associations. Values below the blue line represent negative associations. Confidence intervals that include the blue line are not significant. The y-axes represent estimated effects across time.