The Zurich study. II. The continuum from normal to pathological depressive mood swings

The longitudinal study of a cohort of 591 men and women aged 20 and 21 years respectively at outset, and 23/24 years at a subsequent investigation, was analyzed for the manifestation of depressive syndromes. The syndromes were grouped according to their duration: 1 week once or twice per year (group B), 1 week three or more times per year (C), 2 weeks (D), 4 weeks (E) and 3 months (F). Prevalence rates are given over 1 month, 3 months and 1 year, subdivided by sex. Unexpected identical prevalence rates are found for both sexes up to 3 months. Over 1 year, the ratio shifts to favor the women. Setting out from the hypothesis of a continuum of depressive mood from normal to pathological, groups B to E were examined with respect to the prevailing symptomatology (assessed with an interview and a self-rating questionnaire, the SCL-90R). We found no relevant qualitative differences, only a trend of somatic symptoms becoming more prominent along with increasing duration of episode. Symptomatology thus does not point to further classification. Other criteria, such as subjective impairment, social impairment, illness behavior, discussing depressive mood with parents/friends/employer, treatment, all favor the assumption of a continuum of depressive syndromes from normal to pathological.