Low Vitamin D Increases Risk for Alzheimer’s Disease

Vitamin D, known as the sunshine vitamin due to its mechanism of production in the body, is usually associated with calcium absorption and bone health, but researchers are finding that vitamin D is strongly linked to the risk for Alzheimer’s disease and dementia. Dr. David Llewellyn, from the University of Exeter Medical School in the United Kingdom, co-authored a study published in Neurology, entitled, “Vitamin D and the risk of dementia and Alzheimer disease,” which confirms an increased risk for Alzheimer’s disease in individuals with low vitamin D levels.

“We expected to find an association between low vitamin D levels and the risk of dementia and Alzheimer’s disease, but we actually found that the association was twice as strong as we anticipated,” said Dr. Llewellyn in a news brief from Endocrinology Update written by Clifford Fram. The study used a large sample size–over 1,658 people–of adults older than 65 years of age. All were part of the US population-based Cardiovascular Health Study conducted between 1992-1993 and 1999.

The study was prospective in design, as vitamin D levels (serum 25-hydroxyvitamin D) were determined at baseline, and follow-up evaluation of mental status was conducted using National Institute of Neurological and Communicative Disorders and Stroke/Alzheimer’s Disease and Related Disorders Association criteria. Follow-ups were conducted after approximately 5.6 years, during which time 171 participants had developed all-cause dementia, including 102 cases of Alzheimer’s disease.

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Severely deficient (vitamin D <25 nmol/L) patients were 2.22-times as likely to develop Alzheimer’s than their normal counterparts, while deficient patients (vitamin D 25-50 nmol/L) were 1.69-times as likely. Similarly, the odds ratios for severely deficient and deficient patients to develop all-cause dementia were 2.25 and 2.53, respectively.

This is not the first time vitamin D has been linked to non-skeletal disorders. There is evidence for a link between low vitamin D and severe acute optic neuritis in multiple sclerosis, as well as a benefit of vitamin D supplementation to fighting multiple sclerosis and Parkinson’s disease. Future studies concerning vitamin D supplementation and Alzheimer’s disease would be beneficial, as supplements are a relatively simple solution to the problem of dementia.