Childhood conduct disorder trajectories, prior risk factors and cannabis use at age 16: birth cohort study

AIMS: To investigate prevalence of cannabis use and problem use in boys and girls at age 16 years and to investigate the role of adversity in early life and of conduct disorder between the ages of 4 and 13 years as risk factors for these outcomes. DESIGN: Birth cohort study SETTING: England. PARTICIPANTS: 4159 (2393 girls) participants in the ALSPAC birth cohort providing information on cannabis use at age 16. MEASUREMENTS: Cannabis use and problem cannabis use at age 16 were assessed by postal questionnaire. Material adversity, maternal substance use, maternal mental health and child conduct disorder were all assessed by maternal report. FINDINGS: Cannabis use was more common amongst girls than boys (21.4% vs 18.3%, p=0.005). Problem cannabis use was more common in boys than girls (3.6% vs 2.8%, p=0.007). Early Onset Persistent conduct problems were strongly associated with problem cannabis use (OR 6.46 95% CI 4.06-10.28). Residence in subsidised housing (OR 3.10 95% CI 1.95, 4.92); maternal cannabis use (OR 8.84 95% CI 5.64-13.9) and maternal smoking 20 or more cigarettes per day (OR 3.28 95% CI 1.85-5.82) all predicted problem cannabis use. Attributable risks for adolescent problem cannabis use associated with the above factors were 25%, 13%, 17% and 24% respectively. CONCLUSIONS: Maternal smoking and cannabis use, early material disadvantage and early onset persistent conduct problems are important risk factors for adolescent problem cannabis use. This may have implications for prevention.