Nickan Research Institute Journal of Parathyroid Disease 2345-6558 2 1 2014 01 01 Vitamin D deficiency and psychological disorders 21 25 EN Nematollah Sotodeh-Asl Mohammad-Reza Tamadon Farhad Malek Mehrdad Zahmatkesh Journal Article The studies showed that, Vitamin D is involved in numerous brain processes, regulation of neurotrophic factors, neuroprotection, neuroplasticity and brain development. Vitamin D is crucial not only for bone health but for proper brain development and psychological functioning. However, low levels of vitamin D are associated with depression, schizophrenia and also seasonal affective disorder in adults, but there is conflicting evidence about the relationship between vitamin D deficiency and psychological disorders. Our analysis are consistent with the hypothesis that low vitamin D concentration is associated with psychological disorders, therefore in this review article, PubMed and Web of Science databases were searched from 2000 through 2014. Based on these publications, although our study did not address the issue as to whether the observed differences represent a causal relationship between vitamin D deficiency and psychiatric symptoms, the results are nonetheless important given the significance of vitamin D to overall health. We suggest that increased attention should be given to vitamin D deficiency in psychiatric disorders.