[Bipolar affective disorder. A retrospective study of 158 patients in a well-defined geographical region].

A cohort of 158 patients was identified from 723 patients admitted in 1990 or treated as outpatients in 1991 for affective disorders in three university hospitals in Copenhagen, covering a well-defined catchment area. The cohort was subclassified for seasonal pattern according to DSM-III-R. Meteorological data of temperature, hours of sunshine, rainfall and wind-velocity expressed as mean values/month were obtained from the Institute of Meteorology in Copenhagen.