Trajectory classes of cannabis use and heavy drinking among rural African American adolescents: multi-level predictors of class membership.

Rural African American youth's cannabis use and heavy drinking across adolescence and young adulthood demonstrate distinct developmental courses; a small number of risk factors and measures of biological and perceived stress differentiate class membership prognostically. Variability over time in these measures, specifically an increase in deviant peer affiliation, may help to account for steep increases in young adulthood.