Change in marijuana use from adolescence to young adulthood and its relation to gestational alcohol and marijuana...

Many studies have examined changes in marijuana use across adolescence, but few have examined factors associated with transitions from adolescence to young adulthood. We examined prenatal exposures to alcohol and marijuana and adolescent risk and protective factors that best distinguished among abstinence, continuity, or cessation of marijuana use from 16 to 22 years.

Data were from the Maternal Health Practices and Child Development Project at the prenatal and 16- and 22-year follow-up phases. The offspring were of lower socioeconomic status with an average of 12.8 years of education at 22 years. Participants' frequency and quantity of marijuana use over the past year were used to determine change in use. A discriminant analysis was applied to distinguish among the identified groups. The risk factors considered included prenatal substance exposures and age 16 demographics, behavior, and home environment.

Four categories of transitions were defined based on marijuana use from 16 to 22 years: non-users (n = 193), stop/decrease (n = 81), continue at same level/increase (n = 125), and initiation after the 16-year phase (n = 122). The factors that best distinguished among these groups were peers' marijuana use, delinquency, caregivers' financial strain, prenatal exposure to alcohol and marijuana, and race.

Prenatal alcohol and marijuana exposure were significantly related to transitions of marijuana use from adolescence to young adulthood, controlling for peers' use, behavior problems, and home environment. While gestational marijuana exposure was associated with early initiation/increasing use, alcohol exposure was related to later initiation. The findings emphasize the long-term effects of prenatal exposure to alcohol and marijuana.