Vitamin D, light and mental health.

Vitamin D receptors and vitamin D metabolizing enzymes are present in the central nervous system. Calcitriol (the active vitamin D hormone) affects numerous neurotransmitters and neurotrophic factors, relevant for mental disorders. In the case of depressive disorders, considerable evidence supports a role of suboptimal vitamin D levels. However, the data are not conclusive and further studies are necessary. Especially, the relative importance of the pineal-melatonin system versus the vitamin D-endocrine system for the pathogenesis of seasonal affective disorders is presently unresolved. Two diagnoses, schizophrenia and autism, have been hypothetically linked to developmental (prenatal) vitamin D deficiency, however, also in adult patients, low levels have been reported, supporting the notion that vitamin D deficiency may not only be a predisposing developmental factor but also relate to the adult patients' psychiatric state. Two cases are described, whose psychiatric improvement coincided with effective treatment of vitamin D deficiency.