Evidence for Sex Convergence in Prevalence of Cannabis Use: A Systematic Review and Meta-Regression

Objective: Generally, cannabis use has been more prevalent in men than in women. However, emerging evidence suggests that the prevalence of cannabis use is converging among males and females from recent cohorts. This study aimed to systematically summarize published literature on birth cohort changes in male-to-female ratios in prevalence of cannabis use. Method: Twenty-two studies with a median sample size of 85,052 were identified for inclusion. Data were collected between 1979 and 2010, representing birth cohorts from 1936 to 1999. For quantitative synthesis, male-to-female ratios in prevalence of any cannabis use were calculated for all 5-year birth cohorts available, generating 348 separate ratios among birth cohorts from 1941 to 1995 in 30 countries. Random-effects meta-analyses generated pooled sex ratios, stratified by 5-year birth cohorts. Results: Of the 22 included studies, 10 reported some evidence of sex convergence in cannabis use among more recent cohorts. Quantitative synthesis found that the ratio of cannabis use prevalence in males and females decreased significantly from 2.0 among cohorts born in 1941 to 1.3 among those born in 1995. Conclusions: Findings support the narrowing sex gap in the prevalence of cannabis use. Results are concordant with a broader literature demonstrating sex convergence in prevalence of other substance use, particularly alcohol use and related harms. Both young women and men should be the target of prevention and early intervention efforts. Future research in more diverse global settings, especially in low- and middle-income countries, would enhance the international scope of the findings.