Childhood and Adolescent Predictors of Maturing out of Marijuana Use

Introduction: Little research has been conducted to examine maturing out of marijuana use and the research that has been done has focused primarily on proximal predictors in young adulthood, such as marriage, parenthood, and career. This study examines whether childhood and adolescent risk and protective factors (RPFs) can differentiate adolescent heavy marijuana users who mature out of use from those who continue to use heavily into young adulthood. Our selection of RPFs is based on previous research and includes factors that have differentiated marijuana users from nonusers from the individual, family, and peer domains. These RPFs are assessed in childhood (ages 7-9), early adolescence (ages 10-12), middle adolescence (ages 13-16), and late adolescence (ages 17-19). In addition, we examine reasons for substance use at age 16.

Methods: Data come from the youngest cohort from the Pittsburgh Youth Study, who was followed at least annually from the first grade through approximately age 20 and again at approximately ages 25 and 28 years. Young men who scored in the top 25% in terms of marijuana use frequency during ages 13-16 (mean frequency = 92 times per year) were assigned to the maturing out group (N = 55) if they did not use marijuana in young adulthood (ages 25 and 28) and assigned to the chronic group (N = 47) if they used at least weekly in young adulthood. These young men were also compared to a group of young men who did not use any marijuana prior to age 17 (N=250).

Results: The maturing out and chronic heavy users did not differ significantly in their marijuana use frequency through middle adolescence, although they did differ from age 17 on. T-test and chi square analyses indicated that risk and protective factors measured during childhood throughout adolescence and reasons for use could not differentiate these two groups except for friends’ drug use at ages 17-19, which was higher for the chronic than the maturing out group, and educational aspirations at ages 13-16, which were lower for the maturing out group. In contrast, nonusers differed significantly from heavy users on most of the individual, peer, and family measures with the heavy users scoring worse.

Conclusions: It appears that childhood and adolescent RPFs that differentiate adolescent heavy marijuana users from nonusers cannot prospectively differentiate heavy users who mature out from those who continue to use heavily in young adulthood. Further research is needed to identify turning points and life events during young adulthood that influence whether adolescent heavy marijuana users will continue to use heavily in adulthood or mature out of use to better inform preventive interventions.