Developmental and generational trends in alcohol, cannabis and tobacco use--a ten year cohort analysis.

Six surveys of drug use (including alcohol) among Ontario (Canada) students (grades 7-13) were conducted between 1968-1979. Cohort analyses identified significant increases in the prevalence and incidence of alcohol and cannabis use for all cohorts with, however, some moderation of cannabis use in recent years within the oldest cohort. Recent tobacco use has shown a reduction in the earlier strong trends towards increased use. Developmental influences on drug use were stronger than generational influences. Implications for preventive intervention are discussed.