Is there a gender paradox in the association between conduct problems and cannabis use? A cohort-study among Swedish adolescents

Introduction: Conduct problems (CP) predict cannabis use prospectively but the research is mixed as to whether this association is stronger among girls. A stronger association among girls would suggest a ‘gender paradox’ as both CP and cannabis use is less common in this group. This study aimed to assess whether the longitudinal association between CP and cannabis use in Swedish adolescents is stronger among girls. Methods: Data from two waves of a nationally representative cohort study of Swedish adolescents born in 2001 were used. Baseline measurements were collected in 9th grade (at age 15–16) and follow-up measures at 11th grade (at age 17–18). Results: CP at baseline were significantly associated with cannabis use at follow-up adjusted for hyperactivity problems, emotional problems, socio-demographics, parental monitoring, school grades and truancy at baseline (odds ratio [OR] 1.14, 95% confidence interval [CI] 1.06–1.24) but not when also adjusting for substance use at baseline. Boys were more likely to have used cannabis during the past year, even when controlling for prior substance use (OR 2.29, 95% CI 1.76–2.98). The association between CP and cannabis use was significantly weaker for boys (OR 0.83, 95% CI 0.72–0.95 in the fully adjusted model). The predicted probability of cannabis use was stable at 0.13 for boys across levels of CP, but ranged from 0.05 to 0.16 for girls. Discussion and Conclusion: The longitudinal association between CP and cannabis use was stronger among girls. The findings are indicative of a ‘gender paradox’ in the association between CP and cannabis use.