Multiple Risk Factor Model Predicting Cannabis Use and Use Disorders: A Longitudinal Study

Background: Identification of factors associated with the initiation and continuation of cannabis use is important for any preventive work. Objectives: This study aimed to examine the early life course predictors of cannabis use and the development of cannabis use disorder in early adulthood. Methods: Data from Mater Hospital and University of Queensland Study of Pregnancy (MUSP), a population-based prospective birth cohort study. Participants were a cohort of 2,493 young adults who completed the life-time version of the Composite International Diagnostic Interview-computerized version (CIDI-Auto) at the 21-year follow-up, and for whom data were available from previous follow-ups. Ever use and age at first use of cannabis was assessed via self-report, and cannabis use disorder was measured based on Diagnostic and Statistical Manual version IV (DSM-IV) diagnostic criteria. Life course predictors were obtained between the child's birth and the 14-year follow-up. Results: Of 2,493 young adults, 51.4% reported having ever used cannabis, and 21.1% of young adults were classified as having ever had a cannabis use disorder. Child's gender, changes in maternal marital status, maternal smoking, child school performance, childhood sexual abuse, early adolescence smoking and alcohol consumption, and adolescent aggression/delinquency were strongly associated with young adult cannabis use and use disorder. Exposure to multiple risk factors was associated with greater risk of outcomes. Conclusions: There are a number of strong predictors of cannabis use identified in this study. They suggest that the social context within which children are reared has a major influence on cannabis use and use disorders.