Reciprocal Peer Network Processes on Substance Use and Delinquent Behavior in Adolescence: Analysis from a Longitudinal Youth Cohort Study

Peer context is a pivotal social process shaping adolescent health behavior. Using a representative youth cohort, we aimed to characterize the dynamics in friendship networks among Taiwanese adolescents, and further examined the reciprocal effects between substance use and delinquent behaviors that we hypothesized to manifest via the impacts of dynamic changes of the friendship network. The data were retrieved from the Taiwan Youth Project ( N = 2,566; 51% boys; M age at baseline = 12.3 ± 0.48 years). Participants were requested to nominate their best friends at school and to report their substance use, delinquent behaviors, and pubertal development. Stochastic actor-based modeling was used for the networking analyses. While taking their network structure into account, adolescents select friends based on similarity in class at school (β = 0.929 [standard error = 0.088], p < 0.001) and gender (β = 1.787 [0.188], p < 0.001), but not in their externalizing behaviors. In the behavior dynamics submodel, affiliation with male friends (β = 0.452 [0.178], p = 0.005) and peer substance use status (β = 0.613 [0.124], p = 0.004) were associated with a higher likelihood of engaging in delinquent behavior. Our findings highlight the influence of peers on the co-development of substance use and delinquent behavior in adolescents. Workers in healthcare and the public health sector should be aware of this and formulate prevention policies accordingly.