New research links vitamin D levels in midlife to the toxic tangles of tau protein that accumulate in the brains of people with Alzheimer’s disease.
A statistical analysis of blood samples and brain scans of 793 adults showed that the more vitamin D someone had in their system in middle age, the less tau protein tangles they had years later.
This finding comes from an international team of researchers, and while it doesn’t prove direct cause and effect, it does suggest an association worth looking at.
“These results suggest that high levels of vitamin D in midlife may provide protection against developing these tau deposits in the brain and that low vitamin D levels may potentially be a risk factor that can be modified and treated to reduce the risk of dementia,” says Martin David Mulligan, a neuroscientist at the University of Galway in Ireland.
“Of course, these results need to be further tested with more studies.”
Study participants had their vitamin D levels measured once as part of a baseline assessment at age 39. Brain scans taken 16 years later, on average, were then used to assess levels of tau and amyloid-beta, another protein closely associated with Alzheimer’s.
The study did not look at dementia diagnoses — none of these participants had Alzheimer’s disease at the time of brain imaging — but used abnormal tau and amyloid-beta behavior as proxies for Alzheimer’s-like brain problems that may be taking hold.
Neither tau nor amyloid-beta is naturally destructive; The brain needs to stay healthy. When these proteins begin to corrode and shut down neurons, the damage associated with Alzheimer’s begins, when brain cells break down and communication between them is interrupted.
While the study found no link between vitamin D and amyloid-beta, the link between vitamin D and tau was clear. This applies to the brain as a whole, as well as to certain areas affected by Alzheimer’s in its early stages.
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“To the best of our knowledge, there are no previous studies evaluating the relationship between serum vitamin D and neuroimaging markers of preclinical dementia,” the researchers write in their published paper.
“Supplementation with high doses of vitamin D, and/or long-term benefit in younger, cognitively healthy individuals, may have a greater window of opportunity for disease modification. However, this will require formal testing in clinical trials.”
Past research has linked vitamin D to many health benefits and protection against dementia, but now we have a link between it and a protein associated with Alzheimer’s. While it is still unclear whether tau tangles are the root cause of the disease or just a symptom, they remain. One of the earliest signs that something is wrong.
The researchers point to previous studies that showed vitamin D can improve the brain’s immune system, while its deficiency has been linked to tau protein misbehaving in the brains of mice.
We know that a variety of factors play a role in Alzheimer’s risk, from dangerous proteins to the genetics we’re born with. It’s a complex picture, but scientists are slowly understanding more and more of its subtle details.
This study suggests that getting enough vitamin D may reduce some of that disease risk — so it’s probably worth spending more time in the sun or adding more fish to your diet.
However, vitamin D intake would need to be fully tracked for decades to know for sure, and is linked to dementia diagnosis.
Related: Insomnia may be an early Alzheimer’s warning sign. New research explains why.
“These results are promising, as they suggest an association between higher levels of vitamin D in early middle age and a lower tumor burden on average 16 years later,” says Mulligan.
“Midlife is a time where risk factor modification can have a big impact.”
Research has been published in Neurology Open Access.
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