High blood levels of vitamin D in midlife are associated with lower levels of tau protein in the brain years later, a sign of dementia, according to a study published on April 1, 2026. Neurology® Open Accessthe official journal of the American Academy of Neurology. This study does not prove that vitamin D levels reduce tau levels and risk of dementia. Just show the relevance.
“These results suggest that high vitamin D levels in midlife may protect against the development of tau deposits in the brain, and that low vitamin D levels may be a risk factor that can be modified and treated to reduce the risk of dementia,” said study author Martin David Mulligan, MB BCh BAO, University of Galway, Ireland. “Of course, these results need to be further validated in additional studies.”
The study involved 793 people without dementia, with an average age of 39 years. All participants had their blood vitamin D levels measured at the beginning of the study. After an average of 16 years, they underwent brain scans to measure the levels of tau and amyloid beta proteins in their brains. Both of these are biomarkers for Alzheimer’s disease. High levels of vitamin D were defined as above 30 nanograms per milliliter (ng/mL), and low levels were defined as below that number.
A total of 34% of participants had low vitamin D levels and 5% were taking vitamin D supplements.
The researchers took into account other factors that may influence tau levels, such as age, gender, and symptoms of depression.
Years later, increased vitamin D levels were associated with decreased levels of tau protein, a biomarker for Alzheimer’s disease.
There was no relationship between vitamin D levels and the amount of amyloid beta protein in the brain.
“These results are encouraging because they suggest a link between increased vitamin D levels in early middle age and decreased tau load an average of 16 years later,” Professor Mulligan said. “Midlife is a time when risk factor modification may have a greater impact.”
A limitation of this study is that blood levels of vitamin D were measured only once.
This research was supported by the National Institute of Aging, the National Institute of Neurological Disorders and Stroke, the Irish Research Council and the Irish Health Research Council.
sauce:
American Academy of Neurology
Reference magazines:
https://www.neurology.org/doi/10.1212/WN9.0000000000000057
