OBJECTIVE: This study sought to describe, the natural history of major
depressive disorder in a large group of nonclinical subjects. In
particular, the analysis determined demographic and clinical risk factors
for the recurrence of major depressive disorder. METHOD: Relatives,
comparison subjects (matched to relatives for age and sex), and spouses of
affectively ill probands underwent structured clinical assessments before
and after a 6-year interval. RESULTS: Of 396 individuals who had had only
major depressive disorder that ended before the initial evaluation, 33.8%
(N = 134) developed a new episode during the 6-year follow-up period.
Youth, but not sex, was an important demographic risk factor. The presence
of minor depression at the time of initial evaluation and the number of
symptoms recalled from the worst previous episode were additional clinical
risk factors. At the initial evaluation, 200 other subjects had described a
previous history of both major depressive disorder and a nonaffective
mental disorder. When compared to the subjects who recalled only a history
of major depressive disorder, these subjects were more likely to have been
in an episode of chronic intermittent depression at the initial evaluation
and to recall a greater number of episodes as well as a greater number of
symptoms in the worst episode. A history of a nonaffective mental disorder
significantly increased the risk of relapse into major depressive disorder.
CONCLUSIONS: These findings agree well with a recent review of clinically
based follow-up studies. Thus, youth and a history of nonaffective illness
are important risk factors for the recurrence of major affective disorder
in a broad variety of settings.