05/04/2026
A new international study led by University of Galway suggests that having higher levels of vitamin D in middle age is associated with lower levels of tau protein in the brain, which is a sign of dementia, years later.
While previous research has linked low vitamin D in adults over 70 with an increased risk of dementia. This study is among the first to look at younger adults at mid-life, around the average age of 39, and demonstrates that vitamin D in mid-life could be an important factor to protect future brain health.
The findings have been published today in Neurology Open Access, an official journal of the American Academy of Neurology. The study was led by Professor Emer McGrath and Dr Martin Mulligan, from the College of Medicine, Nursing and Health Sciences at University of Galway and Galway University Hospital. It was carried out in collaboration with Boston University, the Framingham Heart Study and University of Texas San Antonio.
The study involved nearly 800 people with an average age of 39 who did not have dementia. All participants had the level of vitamin D in their blood measured at the start of the study. They had brain scans an average of 16 years later that measured levels of tau and amyloid beta proteins in the brain, which are both biomarkers for Alzheimer’s disease. The results showed that higher vitamin D levels are associated with lower levels of the Alzheimer’s biomarker tau protein years later.
While the study found that higher Vitamin D levels may protect against dementia, it does not prove cause and effect. Further studies will be required to determine if vitamin D supplements could prevent dementia.
Boston University | Framingham Heart Study | American Academy of Neurology (AAN) | The University of Texas at Austin | Health Research Board | National Institute on Aging - NIH
