Reducing adolescents' growth in substance use and delinquency: randomized trial effects of a parent-training prevention intervention.

The relationship between growth in adolescent substance use and delinquency was examined in a longitudinal, randomized controlled study of the Preparing for the Drug Free Years Program (PDFY), a universal family-focused prevention intervention. Latent growth curve modeling was used to analyze 5 waves of data collected from 429 rural adolescents. Results showed that adolescents assigned to the PDFY intervention condition had a slower rate of linear increase over time in both substance use and delinquency compared with adolescents assigned to the control condition. Moreover, pretest level of delinquency was a reliable, positive predictor of growth in substance use, whereas pretest level of substance use did not predict growth in delinquency.