Low vitamin D levels associated with higher dementia risk, study warns
Scientists from Tufts University and other institutions report that higher vitamin D levels in the brain are associated with better cognitive function in older adults.
Vitamin D is both a nutrient obtained from food and a hormone produced by the body after exposure to sunlight. It is a fat-soluble vitamin that helps the body absorb calcium and phosphorus, which are essential for maintaining strong bones.
Research also suggests that vitamin D may play roles beyond bone health. It may help regulate immune function, reduce inflammation, and slow the growth of certain cancer cells. Many organs and tissues contain vitamin D receptors, indicating that it may influence a wide range of biological processes.
Cognitive decline can range from mild cognitive impairment to dementia, a severe loss of memory, reasoning, and other thinking skills that interferes with daily life. In advanced stages, individuals with dementia may require assistance with basic activities such as eating and personal care.
Previous studies have linked blood levels of vitamin D — measured as circulating 25-hydroxyvitamin D (25(OH)D) — to a lower risk of cognitive decline and dementia. However, little has been known about vitamin D levels within the brain itself and how they relate to dementia.
In the current study, researchers analyzed data from 290 participants in the Rush Memory and Aging Project who had vitamin D levels measured in four regions of the brain after death. They examined associations between brain vitamin D levels, cognitive performance before death, and neuropathological findings.
The researchers found that the predominant form of vitamin D in the brain was 25(OH)D3. Higher levels of this compound were associated with a 25% to 33% lower risk of dementia or mild cognitive impairment at the participants’ last clinical evaluation before death.
However, brain vitamin D levels were not associated with specific neuropathological markers observed after death.
The findings suggest that higher vitamin D levels in the brain may be linked to better cognitive function in later life, although the biological mechanisms remain unclear.
The researchers emphasize that further studies are needed to understand how vitamin D may protect brain health and whether increasing vitamin D levels could help prevent cognitive decline.
The study was conducted by M. Kyla Shea and colleagues and published in the journal Alzheimer’s & Dementia.
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