If most adults with mental disorders are found to have a juvenile psychiatric history, this would shift etiologic research and prevention policy to focus more on childhood mental disorders. Our prospective longitudinal study followed up a representative birth cohort (N = 1037). We made psychiatric diagnoses according to DSM criteria at 11, 13, 15, 18, 21, and 26 years of age. Adult disorders were defined in the following 3 ways: (1) cases diagnosed using a standardized diagnostic interview, (2) the subset using treatment, and (3) the subset receiving intensive mental health services. Follow-back analyses ascertained the proportion of adult cases who had juvenile diagnoses and the types of juvenile diagnoses they had. Among adult cases defined via the Diagnostic Interview Schedule, 73.9% had received a diagnosis before 18 years of age and 50.0% before 15 years of age. Among treatment-using cases, 76.5% received a diagnosis before 18 years of age and 57.5% before 15 years of age. Among cases receiving intensive mental health services, 77.9% received a diagnosis before 18 years of age and 60.3% before 15 years of age. Adult disorders were generally preceded by their juvenile counterparts (eg, adult anxiety was preceded by juvenile anxiety), but also by different disorders. Specifically, adult anxiety and schizophreniform disorders were preceded by a broad array of juvenile disorders. For all adult disorders, 25% to 60% of cases had a history of conduct and/or oppositional defiant disorder. Most adult disorders should be reframed as extensions of juvenile disorders. In particular, juvenile conduct disorder is a priority prevention target for reducing psychiatric disorder in the adult population.
