Bi-directional Effects of Peer Relationships and Adolescent Substance Use: A Longitudinal Study.

Understanding the predictors of the onset and maintenance of substance use in adolescence is important because it is a recognized health risk. The present longitudinal study examined whether negative peer influence and peer connectedness predicted changes in adolescent alcohol, cigarette, marijuana, and other illegal drug use, and reciprocally whether substance use predicted changes in peer relationships. Adolescents (N = 1940; 52 % female; 52 % European New Zealanders, 30 % Maori, 12 % Pacific Islander) aged 10-15 years completed measures annually for 3 years. Cross-lagged panel models were used to examine bi-directional effects. Negative peer influence predicted increased use of all substances. In turn, alcohol, cigarette, and marijuana use predicted increased negative peer influence, but this effect was inconsistent over time. Peer connectedness, predicted to diminish the frequency of substance use, was found to be unrelated to it. Breaking the reciprocal cycle between peer coercion and substance use would seem to be useful for reducing substance use.