Objective: This study examined the longitudinal clinical course and adult sequelae of adolescent unipolar major depressive disorder (MDD) using a controlled longitudinal design.
Method: Subjects were 28 adolescents (15.4 +/- 1.3 years) with systematically diagnosed unipolar MDD and 35 group-matched control subjects who participated in a cross-sectional electroencephalogram sleep and neuroendocrine study. Using standardized instruments, interviewers who were blind to subjects' initial diagnoses conducted follow-up clinical assessments 7.0 +/- 0.5 years later in 94% of the original cohort.
Results: The depressed group showed high rates of recurrence of MDD episodes during the interval period (69%). They also had elevated rates of new-onset bipolar disorder (19%). Twenty-three percent of subjects with an initial diagnosis of MDD had no additional depressive episodes after the index assessment. The rate of new onset of depression in the controls was 21%. Low socioeconomic status predicted recurrence of depressive episodes in the MDD group. MDD subjects with recurrence(s) and controls with new onset of depression during the follow-up period had significant psychosocial morbidity, as evidenced by disruption in interpersonal relationships and dissatisfaction with life and decrease in global functioning, compared with both MDD subjects with no further episodes and control subjects who had never been psychiatrically ill. These psychosocial deficits persisted remission from depressive episode(s).
Conclusions: Adolescent unipolar MDD predicts continued risk for recurrences with persistence of depressive episodes and psychosocial morbidity into adulthood. A sizable minority, however, have sustained periods of remission associated with good social adjustment.