Our data document the early onset of major classes of mental disorders. Among affected adolescents, 50% of disorders had their onset by age 6 for anxiety disorders, by age 11 for behavior disorders, by age 13 for mood disorders and by age 15 for substance use disorders. These findings closely approximate those of prospective studies of child and adolescent samples that have documented the incidence and progression of childhood mental disorders.2, 27–29 The early age of onset of anxiety has been well-established and our findings on specific subtypes of anxiety closely track those of prospective community-based research that reveal differential peak periods of onset of specific subtypes of anxiety. 29–31 Prospective studies have also shown that the average age of onset of major depression and dysthymia is between 11 and 14 years,6 with a steady increase in incidence across adolescence that continues through early adulthood. Our cross-sectional data reflect this increase with a near doubling of rates from 13–14 years (8.4%) to 17–18 years (15.4%). Also consistent with prior cross-sectional and prospective research, the median onset of behavior disorders is
