According to a study published in the journal Alzheimer′s & Dementia: Diagnosis, Assessment, and Disease Monitoring, researchers found that vitamin D was associated with living dementia-free for longer. In this study involving more than 12,388 people from the US National Alzheimers Coordinating Center, scientists from the Universities of Calgary in Canada and Exeter in the UK investigated the connection between vitamin D supplementation and dementia.

The average age of the participants was 71, and none of them had dementia at the time they signed up. Also, 37% of the group consumed vitamin D pills at the start of the study. The findings of the study showed that the diagnosis of dementia was 40% lower in the supplement-taking group. The researchers discovered that out of 2,696 people who developed dementia over a ten-year period, 75% of the participants had no exposure to vitamin D at any point during the visits leading up to the diagnosis of dementia.

Although vitamin D was effective in both groups, the researchers discovered that females experienced effects that were much better than those in males. Similar to how alterations in cognition have been associated with an increased risk of dementia, the impacts were more pronounced in those with normal cognition as opposed to those who had mild cognitive impairment.

Additionally, compared to non-carriers, vitamin D effects were also noticeably stronger in those who did not contain the APOEe4 gene, which is known to increase the chance of developing Alzheimer′s dementia. The author of the study explained that those who have the APOEe4 gene have improved intestinal absorption of vitamin D, which reduces the effects of vitamin D supplementation. 

(Source: https://www.tribuneindia.com/news/health/vitamin-d-supplements-may-help-prevent-dementia-study-finds-484502 )