The Zurich study ?A prospective epidemiological study of depressive, neurotic and psychosomatic syndromes

Abstract

How common and how significant are brief depressive episodes (BDE) lasting less than 2 weeks? The authors propose splitting the BDE into two groups: one occurring monthly over 1 year of observation, termed ‘recurrent brief depression’BD), and those occurring less frequently, labeled ‘recurrent brief depression’ BD). From a medical point of view, the RBD are a relevant group. Different thresholds of definition are tested, the narrowest of which (including occupational impairment and predetermined minimum number of symptoms) is accepted for ‘case’-definition. The such defined RBD (SYM) group differs from major depression only by length and frequency of episodes. In a young cohort, its 1-year prevalence rate was found to be 4.4% (males 3.9%, females 4.9%). One-third of these cases needed treatment, a fourth suffered from pronounced subjective and social impairment as well as from persistent suicidal ideation. The self-reporting of subjective impairment, assessed with the SCL-90 symptom inventory and an analog-rating, yields high scores which are in no way inferior to major depression diagnosed with RDC, DSM-III or EDE (SYM) criteria. The RBD (SYM) demonstrate less hypomania than the major depressive disorders. On the other hand, a family history of depression is equally frequent across all groups. The validity of the RBD (SYM) group has yet to be confirmed by a follow-up study, and further research is needed to delineate it from secondary depression. The findings largely support the hypothesis of a continuum from mild and short to more severe, longer lasting depressive syndromes, but they do not exclude heterogeneity of RBD (Angst and Dobler-Mikola 1984b). The diagnostic concept of the RBD and the ‘dysthymic disorders’ of DSM-III are discussed. The similarity between RBD (SYM) and major depression questions the validity of the 2-week duration criterion.