Seasonal Affective Disorders: Relevance of Icelandic and Icelandic-Canadian Evidence to Etiologic Hypotheses

Abstract

These differences seem unexplained by differences in ambient light or climate, thus indicating that genetic factors contribute to the expression of SADs. Compared with earlier findings from a group of adults of wholly Icelandic descent living in nearby rural Manitoba, the etiologic importance of as-yet-undetermined environmental factors unrelated to latitude or ambient light is also indicated.