Results of the Zurich Cohort Study: course of anxiety and depression

Abstract

SummaryIn a longitudinal cohort study of young adults from the Canton of Zurich in Switzerland, the course of anxiety and depressive disorders was examined in 3 interviews over a period of 7 years. The 1-year prevalence rates of panic disorders (including a milder form), generalized anxiety disorder, major depression, and recurrent brief depression were similar from age 21–28 yr. Females prevailed among all diagnoses, their preponderance being strongest for mild panic and major depression. No differential course could be found for the 3 initial diagnostic groups in 1979: the pure anxiety disorders, the pure depression, and the mixed anxiety – depression. Their courses were very similar: 41–52'% recovered, 24–41% developed pure depression, 14–15% manifested a mixed anxious – depressive syndrome, and 5–10% manifested pure anxiety. Compared to controls, all 3 groups showed a tendency to develop into mixed cases and to manifest more recurrences. When the diagnostic information of all 3 interviews was cumulated into longitudinal diagnostic groups, however, differences emerged with respect to severity and chronicity of the disorders. Cases of mixed anxiety-depression were treated more often than cases of pure anxiety or pure depression. Furthermore, in a longitudinal perspective, the mixed cases received a diagnosis more frequently than the cases of pure anxiety disorders or pure depressive disorders, and thus were found to be more recurrent or chronic. With respect to course prediction, a single diagnosis does not differentiate sufficiently and more longitudinal diagnostic information should be taken into account to enhance the certainty of prediction of course and outcome.