Antecedents and consequences of marijuana use trajectories over the life course in an African American population

Background: We examined developmental trajectories of marijuana use among a cohort of urban African Americans followed from first grade to mid adulthood. We compared risk factors in childhood and adolescence and consequences in mid adulthood across trajectory groups.

Methods: Using semiparametric group-based mixture modeling, five marijuana trajectories for men (n=455) and four trajectories for women (n=495) were identified extending from adolescence to young adulthood (age 32). We labeled the four trajectory groups similar for men and women "abstainers," "adolescent only users," "early adulthood decliners," and "persistent users." We named the unique fifth group for men "late starters."

Results: Multivariate multinomial logistic regressions show that childhood problem behaviors, adolescent family involvement, and dropping out of high school differentiated trajectory membership. Analyses comparing the trajectory groups on behavioral, social, and health outcomes at age 42 revealed that for both men and women, those in the persistent trajectory had the most problems, and those in the early adult decliner group also had specific problems. Male late starters also had poor outcomes.

Conclusions: The findings point to the value of identifying specific patterns of substance use over the life course and understanding the differences in their correlates and consequences. The implications of these findings are discussed.