Frequent teenage cannabis use: Prevalence across adolescence and associations with young adult psychopathology and functional well-being in an urban cohort.

Background: Amidst cannabis legalization efforts and laws, we do not fully understand how the youngest frequent cannabis users fare during young adulthood. This study aims to 1) examine the prevalence of cannabis use during adolescence, and 2) investigate links of frequent (i.e., weekly or daily) teenage cannabis use with psychopathology and functional well-being at age 20-compared to no or occasional use.

Methods: Data came from a prospective-longitudinal cohort study (assessments from 2004 to 2018, from ages 7-20) in an urban setting (N = 1482). Substance use was assessed with self-reports between ages 13 and 20. At age 20, participants reported on psychopathology (psychotic symptoms, problematic substance use, aggression, and internalizing symptoms) and functional well-being (delinquency, financial difficulties, social exclusion, general well-being, and not being in education, employment, or training). Covariates were based on self-, parent-, teacher-, and behavioral measures.

Findings: Almost one in five adolescents had used cannabis frequently between ages 13 and 17 (26.6% of males, 9.8% of females). Adjusting nearly 20 potential confounders, frequent teenage cannabis use was associated with age 20 problematic substance use and poorer functional well-being compared to the no cannabis use and the occasional use groups. Frequent teenage cannabis use was more consistently associated with age 20 functional outcomes compared to frequent teenage nicotine or alcohol use.

Conclusions: Frequent teenage cannabis use was common and associated with problematic substance use, more delinquency, and poorer functional well-being at age 20. Accordingly, frequent teenage cannabis users could experience increased difficulties in mastering the transitions of young adulthood.