Prenatal marijuana exposure, age of marijuana initiation, and the development of psychotic symptoms in young adults.

BACKGROUND: Studies have demonstrated that an early age of onset of marijuana use (EAOM) is associated with a higher risk of developing psychotic symptoms (PS) compared to initiating marijuana use at a later age or not at all. Research has also found that prenatal marijuana exposure (PME) predicts EAOM. This report evaluates the relationships among PME, EAOM, and PS.
METHOD: Subjects were initially interviewed in their fourth prenatal month. Women and offspring who completed the birth assessment (n = 763) were selected for follow-up. Women and their offspring were followed until the offspring were 22 years of age: 596 offspring were evaluated. At age 22, PS were assessed in the offspring with the Diagnostic Interview Schedule using DSM-IV criteria. Analyses controlled for significant covariates including other prenatal substance exposures, race, gender, and offspring substance use at 22 years.
RESULTS: PME and EAOM significantly predicted increased rates of PS at 22 years controlling for other significant covariates. The direct effect of PME on PS was marginally significant (p = 0.06) when EAOM was entered into the model and other covariates were fixed. In the mediation analysis, EAOM did not significantly mediate the association between PME and PS, controlling for significant covariates, nor was the indirect pathway significant when structural equation modeling was used. The total effect of the direct and indirect pathways was significant.
CONCLUSIONS: In addition to EAOM, PME may also play a role in the association between marijuana use and the development of PS. This could highlight a new area for prevention.