The longitudinal influence of peers on the development of alcohol use in late adolescence: a growth mixture analysis.

This study examines heterogeneity in the developmental trajectories of alcohol use in adolescents and the accompanying trajectory-specific longitudinal influence of exposure to their deviant peers. Using a national data set on alcohol use (N = 188), a growth mixture model capturing growth trajectories in adolescent alcohol use from ages 14 to 18 years was first examined. This was followed by an investigation of age-varying influences of peers on adolescent alcohol use and the co-development of peer influence and adolescent alcohol use. Results of growth mixture modeling of repeated-measures data on adolescent alcohol use showed two distinct latent classes of developmental trajectory with significant differences in levels of use. Analyses of exposure to deviant peer and adolescent alcohol use variables indicated differential effects of peers across trajectory classes. Stronger prospective influences for the trajectory group having a low initial status of use were found. Findings from this study suggest the need to consider heterogeneity in the study of peer influence on alcohol use during adolescence to facilitate more refined targeting of prevention/intervention programs.