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Vitamin D deficiency increased dementia, Alzheimer's disease risk

Vitamin D deficiency is associated with an increased risk for dementia and Alzheimer’s disease, according to recent study findings published in Neurology.

“We expected to find an association between low vitamin D levels and the risk of dementia and Alzheimer’s disease, but the results were surprising — we actually found that the association was twice as strong as we anticipated,” David J. Llewellyn, PhD, of the University of Exeter Medical School in the United Kingdom, said in a press release.

David J. Llewellyn

Llewellyn and colleagues evaluated 1,658 adults aged 65 years and older without dementia to determine the effect of vitamin D levels on dementia risk. Participants were followed for a mean of 5.6 years.

At follow-up, 171 participants developed all-cause dementia while 102 developed Alzheimer’s disease.

Compared with participants who were not 25-hydroxyvitamin D (25(OH)D) deficient, those who were deficient had a 51% increased risk for developing all-cause dementia or Alzheimer’s disease, while those who were severely deficient had a 122% increased risk. Similarly, 25(OH)D concentrations below 50 nmol/L increased the risk of all-cause dementia and Alzheimer’s disease.

“Clinical trials are now needed to establish whether eating foods such as oily fish or taking vitamin D supplements can delay or even prevent the onset of Alzheimer’s disease and dementia,” Llewellyn said. “We need to be cautious at this early stage and our latest results do not demonstrate that low vitamin D levels cause dementia. That said, our findings are very encouraging, and even if a small number of people could benefit, this would have enormous public health implications given the devastating and costly nature of dementia.”

Disclosure: See the full study for a complete list of financial disclosures.