Identification and prediction of drinking trajectories in early and mid-adolescence.

The aim of this study was to identify subgroups of early and mid-adolescents with different drinking trajectories. In addition, we examined whether gender, parental, and peer factors predicted adolescents' membership of these drinking trajectories. We used longitudinal data of 428 families (fathers, mothers, mid-adolescents, and their younger siblings). Latent Class Growth Analyses were performed to identify drinking trajectories. Four drinking trajectories emerged for early adolescents: abstainers, light drinkers, increasers, and heavy drinkers. For mid-adolescents, we identified a fifth group (stable drinkers) in addition to the four trajectories identified for early adolescents. Our results showed that being a boy, having a best friend or father who drinks heavily, and having parents who are permissive toward adolescents' alcohol creates increased risk for both siblings to attend the more heavy drinking trajectories.