Exposure to sunlight, vitamin D and schizophrenia.

The hypothesis that vitamin D deficiency in pregnancy or early infancy may contribute to the aetiology of schizophrenia was tested by examining the relationship between population exposure to sunlight, which promotes the synthesis of vitamin D in the summer months, and the monthly rate of schizophrenic births in two large data sets--22,000 schizophrenic patients born in England or Wales between 1921 and 1960, and 8000 born in Scotland between 1932 and 1960. No convincing relationship could be found in either cohort.