Copeland WE, Hill SN, Shanahan L, et al. - For a range of adult outcomes, most problematic was daily, continued-over-time cannabis use beginning in adolescence. Later risk was not eliminated completely in correlation with cessation of early use; but fewer negative outcomes were evident with early cessation, with weaker effect sizes.

• The mixed findings reported in research on associations of early cannabis use with adult functioning might be due to the wide variations in the definitions of early cannabis use.

• A 20+-year longitudinal, community-representative study of 1,420 participants form the basis for these analyses.

• In models that adjusted for gender and race/ethnicity, all definitions of early use correlated with multiple adult outcomes.

• In models that further adjusted for childhood psychiatric problems and family adversities, association of only daily use and a persistent developmental subtype (defined as daily/problematic use that began in adolescence and continued into early adulthood) was observed with later substance use/disorders, poorer functional outcomes, and derailments in the transition to adulthood.