MONDAY, April 6, 2026 (HealthDay News) -- Higher vitamin D levels in midlife are associated with lower levels of the Alzheimer disease biomarker tau protein years later, according to a study published online April 1 in Neurology Open Access.
Martin David Mulligan, from the School of Medicine at the University of Galway in Ireland, and colleagues examined whether serum vitamin D in early midlife is associated with neuroimaging markers of preclinical dementia. The analysis included 793 participants (53 percent women; mean age, 39 years) with available serum 25-hydroxyvitamin D (25[OH]D) and amyloid- (424 individuals) and/or tau-positron emission tomography (PET; 369 individuals).
The researchers found that during a mean follow-up of 16 years, higher serum 25(OH)D (≥30 ng/mL) was associated with lower global (β = −0.022) and composite (β = −0.023) tau-PET deposition. However, there was no association observed between serum 25(OH)D and amyloid-PET burden.
"These results suggest that higher vitamin D levels in midlife may offer protection against developing these tau deposits in the brain and that low vitamin D levels could potentially be a risk factor that could be modified and treated to reduce the risk of dementia," Mulligan said in a statement. "Of course, these results need to be further tested with additional studies."