Evidence mounts that vitamin D may be key to preventing dementia

A new large-scale study has shown that warding off dementia early may be as simple for some as taking a vitamin D supplement.

Previous research has found that low levels of vitamin D are linked to a higher risk of developing dementia. The hormone helps remove amyloid from the brain – its accumulation is a hallmark of Alzheimer’s disease – and it may also assist in preventing tau build-up, another protein at play in the development of dementia.

While vitamin D is obtained through direct sunlight and diet, studies have consistently shown around 40% of Americans to be D-deficient, with the figure higher depending on age and skin color, among other factors.

Researchers looked at the link between dementia and vitamin D supplements in close to 12,400 people who had a mean age of 71 and were dementia-free at the start of the study. Within this group 4,637 took vitamin D supplements.

Of the 2,696 participants who progressed to dementia in the following decade, 75% had no exposure to vitamin D supplements prior to diagnosis. The remaining quarter had baseline exposure at the beginning of the study.

“Our findings give key insights into groups who might be specifically targeted for vitamin D supplementation,” said Zahinoor Ismail, lead researcher and professor at the University of Calgary and University of Exeter. “Overall, we found evidence to suggest that earlier supplementation might be particularly beneficial, before the onset of cognitive decline.”

Researchers found 40% fewer dementia diagnoses among the 4,637 participants who took vitamin D supplements, compared to the cohort that did not.

Interestingly, the study also found that vitamin D supplements seemed to benefit a few subsets of participants more: women, those with normal cognition as opposed to mild impairments, and in people who did not carry the APOE-e4 gene.

Around 40-65% of dementia sufferers carry this gene, which is associated with the regulation of lipid metabolism, and is linked to increase risk of developing the disease. Researchers believe that those with this gene absorb vitamin D from the intestine, which would potentially alter the efficacy of supplements.

“Preventing dementia or even delaying its onset is vitally important given the growing numbers of people affected,” said Byron Creese, co-author and senior lecturer in neuroscience at the University of Exeter. “The link with vitamin D in this study suggests that taking vitamin D supplements may be beneficial in preventing or delaying dementia.”

The study was published in the journal Alzheimer's & Dementia: Diagnosis, Assessment & Disease Monitoring.

Source: University of Exeter via EurekAlert!