Scientists from the University of Galway in Ireland have found that higher vitamin D intake during middle age could be linked to a lower risk of dementia. The study recruited nearly 800 participants with an average age of 39, with their vitamin D levels tested at the start and then subjected to a brain scan 16 years later to measure their levels of tau protein deposits. While no correlation was found between vitamin D and amyloid beta proteins, those with more vitamin D in their blood tended to have lower tau in their brains years later. The researchers believe these findings could lead to better preventative care for people at risk of developing dementia later in life. An analysis from 2025 also revealed a similar connection between Vitamin D levels and Alzheimer's risk, suggesting that low vitamin D can increase a person's likelihood of developing Alzheimer's by 49%.