The Zurich study. III. Diagnosis of depression.

A 23- to 24-year-old age group representative of the general population of the Canton of Zurich, was used to detect depression. The classifications obtained by means of the Feighner, RDC and DSM-III criteria are compared with our own concept, which differs in some aspects. A minimum of 2 weeks of depression is labeled as EDE (extensive depressive episode). Instead of the presence of a minimum number of depressive symptoms, social impairment at work is first examined as a case-defining criterion (EDE[WORK]); in a second step, a diagnostic threshold of three, and five, depressive symptoms for males and females respectively is adopted (EDE[SYM]). The consequences are presented relating to prevalence, incidence, sex distribution, overlap with other diagnostic concepts, severity, bipolarity and family history. An unequal sex distribution in depression is shown to be an artifact of definition. Preference should go to a case-definition that could be specifically adapted to a given problem. On the whole, the DSM-III and EDE(WORK) criteria appear to be too broad. We will henceforth prefer the RDC and EDE(SYM) criteria, which both, however, necessitate further methodological and empirical study.