Developmental trajectories of marijuana use from adolescence to adulthood: personal predictors.

OBJECTIVE To investigate the relationship between early adolescent personal characteristics and the developmental trajectories of marijuana use extending from early adolescence to adulthood. DESIGN This study used a longitudinal design. Data were obtained using structured questionnaires administered by trained interviewers. SETTING Interviews were conducted in the participants' homes in upstate New York. PARTICIPANTS Participants were drawn from a randomly selected cohort and were studied prospectively since 1975 (T1) at a mean age of 6 years. The follow-up data used for this study were collected at 6 time points when the participants were aged between 14 and 37 years in 1983 (T2), 1985-1986 (T3), 1992 (T4), 1997 (T5), 2002 (T6), and 2005-2006 (T7). MAIN OUTCOME MEASURES Developmental trajectories of marijuana use. RESULTS Semiparametric group-based modeling and logistic regression analyses were used to analyze the data. The following 5 distinct trajectories of marijuana use were identified: nonusers or experimenters, occasional users, quitters or decreasers, increasing users, and chronic users. Chronic users compared with other groups studied (nonusers or experimenters, occasional users, quitters or decreasers, and increasing users) reported low self-control, externalizing behavior, and an orientation to sensation seeking. CONCLUSIONS Personal attributes of low self-control, externalizing behavior, and an orientation to sensation seeking have long-term predictive power for distinct trajectories of marijuana use over time. The importance of these findings for prevention and treatment programs is discussed.