Child maltreatment and cannabis use in young adulthood: a birth cohort study

Aims: To investigate whether: (1) child maltreatment is associated with life-time cannabis use, early-onset cannabis use, daily cannabis use and DSM-IV cannabis abuse in young adulthood; and (2) behaviour problems, tobacco use and alcohol use at age 14 are associated with cannabis use. Design: Birth cohort using linked government agency child protection data to define exposure to child maltreatment. Setting: The Mater-University of Queensland Study of Pregnancy in Brisbane, Australia. Participants: Of the original cohort of 7223 mother and child pairs, obtained from consecutive presentations for prenatal care at a hospital serving a cross-section of the community, 3778 (52.3%) of the young people participated at age 21\ua0years. Measurements: Exposure to child maltreatment was established by substantiated government agency reports. Cannabis outcomes were by self-report questionnaire and Composite International Diagnostic Interview (CIDI)-Auto at age 21. Associations were adjusted for a range of potential confounders. Additional adjustment was carried out for variables measured at age 14—youth behaviour problems [Achenbach Child Behavior Checklist (CBCL)], tobacco use and alcohol use. Findings: After adjustment, substantiated child maltreatment was associated with any life-time cannabis use [odds ratio (OR)\ua0=\ua01.60, 95% confidence interval (CI)\ua0=\ua01.08–2.39], cannabis use prior to age 17 (OR\ua0=\ua02.47, 95\ua0% CI\ua0=\ua01.67–3.65), daily cannabis use (OR\ua0=\ua02.68, 95% CI\ua0=\ua01.49–4.81) and DSM-IV cannabis abuse/dependence (OR\ua0=\ua01.72, 95% CI\ua0=\ua01.07–2.77). Externalizing behaviour and tobacco and alcohol use at age 14 were associated significantly with almost all cannabis outcomes (P\ua