Dementia affects an estimated 55 million individuals globally, a figure that is likely to climb as the global population ages. Scientists need to learn more about what causes dementia so they can find ways to slow it down or stop it.
Researchers from Tufts University have conducted the first research to examine vitamin D levels in brain tissue, especially in people with various rates of cognitive deterioration. They discovered that participants in this group had improved cognitive performance and greater amounts of vitamin D in their brains.
The research was presented in Alzheimer’s & Dementia: The Journal of the Alzheimer’s Association today.
“This research reinforces the importance of studying how food and nutrients create resilience to protect the aging brain against diseases such as Alzheimer’s disease and other related dementias,” says senior and corresponding author Sarah Booth.
Vitamin D boosts immunity and bone health. In addition to fortified foods (such milk or orange juice) and fatty fish, vitamin D may also be obtained by short sun exposure.
“Many studies have implicated dietary or nutritional factors in cognitive performance or function in older adults, including many studies of vitamin D, but all of them are based on either dietary intakes or blood measures of vitamin D,” adds lead author Kyla Shea. “We wanted to know if vitamin D is even present in the brain, and if it is, how those concentrations are linked to cognitive decline.”
Booth, Shea, and their team looked at brain tissue samples from 209 people who took part in the Rush Memory and Aging Project, which started in 1997 and is a long-term study of Alzheimer’s disease. Researchers at Rush University looked at how well the older people who took part in the study thought and remembered things as they got older, and they also looked for changes in their brain tissue after they died.
The study examined vitamin D in four regions of the brain: two regions associated with Alzheimer’s disease-related changes, one region associated with dementias related to blood flow, and one region without known associations with cognitive decline due to Alzheimer’s disease or vascular disease. They discovered that vitamin D existed in brain tissue and that higher levels of vitamin D in each of the four areas of the brain were associated with improved cognitive performance.
However, vitamin D levels in the brain were not related with any of the physiological indicators of Alzheimer’s disease in the investigated brain, including amyloid plaque formation, Lewy body illness, or indications of chronic or tiny strokes. This implies that the precise effect of vitamin D on cognitive processes has yet to be determined.
“Dementia is multifactorial, and lots of the pathological mechanisms underlying it have not been well characterized,” Shea adds. “Vitamin D could be related to outcomes that we didn’t look at yet, but plan to study in the future.”
Vitamin D levels can also differ by race or ethnicity, and most of the people in the original Rush cohort were white. To examine further brain alterations linked to cognitive loss, the researchers are preparing follow-up experiments with a more diversified subject pool. They are hoping that this research may help people better grasp how vitamin D may help prevent dementia.
Experts warn, though, that taking large amounts of vitamin D supplements as a preventive measure is not a good idea. For individuals aged 1 to 70, 600 IU of vitamin D is advised, and for those over 70, 800 IU; exceeding these doses may be harmful and has been associated with an increased risk of falling.
“We now know that vitamin D is present in reasonable amounts in human brains, and it seems to be correlated with less decline in cognitive function,” Shea adds. “But we need to do more research to identify the neuropathology that vitamin D is linked to in the brain before we start designing future interventions.”
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