Ages of onset of psychiatric disorders in a community population of older adolescents.

OBJECTIVE Ages of onset of psychiatric disorders, as well as the link between early onset and later psychosocial functioning, were examined in a community population of older adolescents. METHOD Subjects were 386 adolescents who were participants in an ongoing 14-year longitudinal study. At age 18, lifetime diagnoses and ages of onset of major depression, phobias, post-traumatic stress disorder, and substance disorders were assessed using the NIMH Diagnostic Interview Schedule, Revised Version. Behavioral, emotional, and academic functioning in later adolescence were evaluated through self-report measures and school records. RESULTS Almost one fourth of the adolescents met criteria for at least one disorder by age 14. Simple phobias emerged earliest (by early childhood), whereas for major depression and substance disorders the peak risk periods for onset were midadolescence. The early onset (by age 14) of disorders was associated with continued impairments in behavioral and emotional functioning in late adolescence (at age 18). Furthermore, the early onset of disorders, compared to later onset (ages 15 through 18), increased the risk for additional co-occurring disorders. CONCLUSIONS The striking levels of early psychopathology and associated long-term deficits in functioning found in this community population underscore the need for programs of early intervention.