Low vitamin D concentrations are associated with prevalent Alzheimer’s dementia and cognitive impairment. 1,25-Dihydroxy vitamin D3 receptor and 1α-hydroxylase, the enzyme responsible for synthesizing the bioactive form of vitamin D, are found throughout the human brain.
Alzheimer’s is caused by the abnormal build-up of amyloid plaques. In vitro, vitamin D increases the phagocytic clearance of amyloid plaques by stimulating macrophages and reduces amyloid-induced cytotoxicity and apoptosis in primary cortical neurons. Vitamin D deficiency has also been linked to vascular dysfunction and ischemic stroke riskas well as brain atrophy. This suggests that a decrease in the concentration of vitamin D leads to Alzheimer’s and dementia.
