Longitudinal Peer Influences on Adolescent Externalizing Behavior Problems are Moderated by a Genetic Susceptibility Gene Score

• In Event: 2-015 - Peer influences on child and adolescent social competencies: Evaluating genetic and environmental influences

Integrative Statement

Introduction. Peers become a stronger source of environmental influence as adolescents begin to spend more time with peers. Time spent with peers who encourage antisocial behavior can facilitate high risk behaviors among adolescents; peer susceptibility, however, is not uniform across adolescents and some youth are more and less influenced by their peers. Research on genetic susceptibility has identified genetic markers related to differences in environmental sensitivity. Few studies, however, have taken a polygenic approach to quantifying genetic sensitivity to environments. In the current study we used adolescent data from the PROSPER project (90% Caucasian, 60% female) to investigate the influence of peer externalizing behavior problems on target-adolescent externalizing behavior problems over the course of adolescence. In addition, we tested the hypothesis that an aggregate genetic risk score implicated in environmental susceptibility would moderate peer influence.
Method. Data for the current study comes from a subset of participants from the PROSPER project (N = 1,776) who also provided DNA. Eight waves of data spanning 6th to 12th grade were used. At each wave, adolescents completed a series of 12 items about the frequency of externalizing behavior problems in the prior year. During the first 5 waves, peer nomination data were collected by asking adolescents to list their best/closest friends in their grade. Peer Externalizing was derived from the same 12 item externalizing behavior problems measure among the target-adolescent’s peers who reciprocally nominated them as best/close friend. Three genes were included in the Differential Susceptibility (DS) gene score: DRD4 (0 = 7-, 1 = 7+), 5-HTTLPR (0 = L/L vs. 1 = S-carrier), and GABRA2 (rs279845, 0 = C/C, .5 = C/T, 1 = T/T), which were chosen based on prior work. For Adolescent Externalizing, 8 waves of data were used to create a linear growth model using wave 5 as the intercept. For Peer Externalizing, the 5 available waves (waves 1-5) were used to estimate linear growth term and wave 5 intercept.
Results. Results (Figure 1) showed that the Peer Externalizing intercept and slopes significantly predicted the Adolescent Externalizing intercept and slope (β’s = .462 and .497, respectively). In addition, the DS gene score was significantly related to the Adolescent Externalizing intercept (β = .052, p < .05) and slope (β = .055, p < .05) after controlling for Peer Externalizing. This result suggests that more copies of putative sensitivity alleles were related to higher (intercept) and faster increase (slope) in externalizing behavior problems during adolescence. Next, the interaction between the DS gene score and the Peer Externalizing intercept and between the DS gene score and Peer Externalizing slope were added to the model. Results showed the interaction between the DS gene score and Peer Externalizing intercept on the Adolescent Externalizing intercept was significant (b = .926, p < .05) as was the interaction for the Adolescent Externalizing slope (DS gene score*PeerSlope; b = .859, p < .019). Results are discussed in terms of peer influence on externalizing behavior problems in adolescence and genetic susceptibility to environments.

Authors

• Gabriel Schlomer, University at Albany
  Presenting Author

• H. Harrington (Bo) Cleveland, Penn State University
  Non-Presenting Author

• David Vandenbergh, The Pennsylvania State University
  Non-Presenting Author

• Mark Feinberg, The Pennsylvania State University
  Non-Presenting Author