The median age at onset of alcohol abuse with or without dependence was 14 years, with 15.1% meeting diagnostic criteria by 18 years of age. Drug abuse was characterized by a similarly young median age at onset and with a prevalence of 16.4% among the oldest adolescents. These adolescent lifetime prevalence estimates for abuse can be compared with adult prevalences observed in the National Comorbidity Survey–Replication, a study that used parallel methods and was conducted concurrently with the NCS-A. Lifetime prevalence of alcohol abuse in the adult survey (18.6%) was only marginally higher than the adolescent prevalence we observed, whereas the prevalence of drug abuse among adults (11.1% overall and 15.1% for the youngest cohort aged 19–30) was actually lower than the adolescent prevalences we estimated.16,17
