Objective: This paper presents retrospective and prospective data regarding time course parameters of major depressive disorder (MDD) in community adolescents (14 to 18 years old): time to onset and recovery and, among those who recovered, time to recurrence.
Method: Diagnostic interviews were conducted with 1,508 randomly selected high school students. Three hundred sixty-two had experienced at least one past or current episode of MDD.
Results: Mean age at onset of first episode was 14.9 (SD = 2.8). Early MDD onset was associated with female gender and suicidal ideation. MDD episode duration ranged from 2 to 520 weeks, with a mean of 26.4 weeks (SE = 3.3) and a median of 8.0 weeks. Longer episodes were observed in those whose depression occurred early (at or before age 15), whose depression had been accompanied by suicidal ideation, and for whom treatment was sought. Of the adolescents who recovered, 5% relapsed within 6 months, 12% within 1 year, and approximately 33% within 4 years. Shorter time to recurrence was associated with prior suicidal ideation and attempt and with later first onset.
Conclusions: Risk of MDD is low in childhood, increasing substantially with adolescence. The majority of episodes in community adolescents are relatively brief, although the risk of recurrence is substantial. Suicidal behaviors are important mediators of episode duration and of recurrence.