Higher Vitamin D in Midlife May Be Associated with Lower Levels of Alzheimer’s Biomarker Years Later

In new research, Dr Martin David Mulligan of the University of Galway and colleagues followed almost 800 participants from the Framingham Heart Study for more than a decade and a half, examining whether vitamin D levels measured in their 30s were linked to changes in the brain later in life. They found that individuals with higher circulating levels of vitamin D had lower accumulations of tau — a protein that forms harmful tangles in the brains of people with Alzheimer’s disease — when they were analyzed about 16 years later. The association held even after adjusting for a wide range of factors, including age, sex, cardiovascular health, smoking, depression and body mass index.

Low vitamin D levels in midlife may represent a potentially modifiable target to mitigate the risk of neuroimaging signs of preclinical dementia. Image credit: Aloísio Costa Latgé.

Dementia is a major contributor to global morbidity, affecting approximately 57 million people worldwide.

“Our results suggest that higher levels of vitamin D in midlife may offer protection against the development of tau deposits in the brain and that low levels of vitamin D could potentially be a risk factor that could be modified and treated to reduce the risk of dementia,” Dr. Mulligan said.

“Of course, these results need to be further tested by additional studies.”

The study is based on data from 793 adults (53% women, average age – 39 years) who did not have dementia at the time of brain imaging.

Participants had their blood levels of 25-hydroxyvitamin D measured between 2002 and 2005, then underwent positron emission tomography (PET) scanning between 2016 and 2019 to detect tau and amyloid deposits.

Tau accumulation, particularly in regions such as the entorhinal cortex and temporal lobes, is thought to play a central role in the early stages of Alzheimer’s disease.

The researchers found that higher levels of vitamin D were associated with lower tau load, both in the brain and in these particularly vulnerable regions.

“In total, 34% of participants had low vitamin D levels and 5% were taking vitamin D supplements,” they reported.

The findings add to a growing body of evidence linking vitamin D to brain health, although most previous studies have focused on older adults or clinical outcomes like dementia diagnosis rather than early preclinical changes in the brain.

Scientists suggest that vitamin D at midlife may represent a potentially modifiable target to reduce the risk of neurodegenerative changes before symptoms appear.

Yet the study does not prove that vitamin D directly prevents tau accumulation or dementia. It measured vitamin D at one time and did not track changes in levels over the intervening years. It also did not test whether supplementation would change brain results.

“These results are promising, as they suggest an association between higher vitamin D levels in the early 50s and lower tau load on average 16 years later,” Dr. Mulligan said.

“Midlife is a time when changing risk factors can have a greater impact. »

The results appear in the newspaper Neurology.

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Martin David Mulligan and others. 2026. Association of circulating vitamin D in midlife with increased Tau-PET burden in adults without dementia. Neurology 2 (2): e000057; doi: 10.1212/WN9.0000000000000057