vitamin d and neurology vitamin d and neurology vitamin d is a steroid hormone that plays a vital role in calcium and phosphate absorption. in recent studies, several associations between low levels of vitamin d, or hypovitaminosis d, and neuropsychiatric disorders have begun to surface. these disorders include, but are not limited to: alzheimer's disease, parkinson's disease, multiple sclerosis, epilepsy, schizophrenia, and autism. vitamin ddrug classcholecalciferol (d3)class identifiersuserickets, osteoporosis, vitamin d deficiencyatc codea11ccbiological targetvitamin d receptorclinical datadrugs.commedfacts natural products