Season and mental illness in an Arctic area of northern Finland.

Abstract

The seasonal variation in mental disturbances was examined in 1251 reindeer herding males in an arctic area of northern Finland using the psychiatric section of the Cornell Medical Index questionnaire (CMI-MR). The mean age of subjects was 43 years. One third of them were full-time reindeer herders and 1/10 were Lapps. The prevalence of mental disorders (CMI-MR at least 5) was estimated at 14%, and it showed peaks in spring and autumn. The pattern was repeated for different varieties of illness, except for depression which showed a single cycle with the highest prevalence in the light season. The authors conclude that mental disorders in the arctic are most common in spring and autumn, and they question the common belief in mid-winter as the most common season for mental disorders.