Is there a connection between dementia and vitamin D? An observational study using a sample of 12,000 older adults, has shown that exposure to vitamin D supplementation was linked to a 40% lower dementia incidence rate compared with no exposure, according to the research of Zahinoor Ismail, MD, of the University of Calgary in Canada and the University of Exeter in England, and co-authors.
MedPage Today’s recent article entitled, “Lower Dementia Incidence Linked With Vitamin D Supplements,” reports that the results were consistent across three vitamin D formulations, the researchers wrote in Alzheimer’s & Dementia: Diagnosis, Assessment & Disease Monitoring. The effects were greater in females, in apolipoprotein E ε4 (APOE4) non-carriers, and in people with normal cognition versus those with mild cognitive impairment.
The study may offer insight into who might benefit from vitamin D supplementation, Ismail suggested. “We know that vitamin D has some effects in the brain that could have implications for reducing dementia, however, so far, research has yielded conflicting results,” he said in a statement.
However, the findings don’t mean vitamin D supplements should be used to prevent dementia, said Claire Sexton, DPhil, senior director of scientific programs and outreach at the Alzheimer’s Association in Chicago, who wasn’t involved with the study. “It is not recommended to start vitamin D supplementation to reduce dementia risk,” she told MedPage Today.
“It is important to note that this study is an observational study, not an intervention, so it cannot establish causation,” Sexton pointed out.
“Also, a significant limitation to the study is that neither vitamin D levels at baseline and follow-up, nor dose and duration of supplementation, were available or analyzed,” she added. “As a result, further research is needed in this area.”
Ismail and co-authors studied 12,388 participants in the National Institute on Aging National Alzheimer’s Coordinating Center (NACC) database who had normal cognition or mild cognitive impairment at baseline. The study participants came from Alzheimer’s Disease Research Centers from 2005 to 2021. Exposure to vitamin D supplementation was based on NACC medication forms that assessed three formulations: calcium-vitamin D, cholecalciferol and ergocalciferol.
Both mild cognitive impairment and depression were more frequent in the non-exposed group. Over 10 years, 2,696 participants progressed to dementia. Among them, 74.8% (2,017 people) had no exposure to vitamin D supplements. Five-year dementia-free survival was 83.6% for those exposed to vitamin D and 68.4% for the non-exposed group. Each vitamin D formulation on its own was associated with a lower dementia incidence rate compared with no exposure.
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Reference: MedPage Today (March 1, 2023) “Lower Dementia Incidence Linked With Vitamin D Supplements”