Predicting adolescent substance use: the effects of depressed mood and positive expectancies.

This study examined whether sixth-graders' depressed mood and positive substance use expectancies predicted increases over the next two years in students' lifetime and 30-day cigarette, alcohol, and marijuana use, and whether sixth graders' positive substance use expectancies moderated the relationship between baseline depressed mood and changes over the next two years in the use of these substances. Study data came from a randomized controlled trial of Project ALERT, a school-based substance use prevention program, in which students from 34 schools completed self-report surveys as sixth (n=5782), seventh (n=5065), and eighth graders (n=4940). Primary analyses were performed using Hierarchical Nonlinear Modeling. Over time, there were significant effects of baseline positive expectancies on each of the six measures of substance use. Baseline depressed mood predicted increases over time only for lifetime use of cigarettes and alcohol, and for 30-day alcohol use. Positive expectancies significantly moderated the effects of adolescent depressed mood only on lifetime marijuana use. Although depressed mood predicted substance use for half of our variables, our results suggest that positive expectancies are a more consistent predictor of adolescent substance use, and that they may moderate the effects of depressed mood on marijuana, but not cigarette or alcohol, use. Substance use prevention programs may benefit from addressing adolescents' perceptions about the positive consequences of drug use.