Vitamin D and Dementia Risk

For years I’ve been writing about the important role of vitamin D as it relates to general health and brain health in specific. And with good reason. The medical research literature has long explored the myriad mechanisms by which vitamin D functions in the human body to keep us healthy.

Recently, the importance of vitamin D for the brain has been reinforced by two compelling studies. The first report comes to us from researchers at Tufts University and involved the analysis of the brains of 290 deceased individuals. None of these individuals had dementia when they were originally enrolled in the study. They were followed as part of the Rush Memory and Aging Project and had their cognitive function assessed throughout the study. After they died, the vitamin D level was determined in four key brain areas, all of which have been implicated in various forms of dementia.

The results of these data revealed that having higher levels of vitamin D in these important brain areas was associated with a compelling 25%-33% lower chance of demonstrating dementia or mild cognitive impairment at the time of the individual’s last evaluation before death.

Upon reading this report, a conclusion might be that the study affirms the need to take a vitamin D supplement. But that would be an inappropriate extrapolation of the data. Indeed, the study didn’t make clear whether the subjects were taking any type of vitamin D supplement or not.

Nonetheless, the question persists. And fortunately, more information related to this question recently appeared in the journal, Alzheimer’s & Dementia: Diagnosis, Assessment & Disease Monitoring. The study followed 12,388 non-demented adults for 10 years. The individuals were stratified as to whether or not, at the beginning of the study, they had taken any form of vitamin D in the past. If any of the subjects started vitamin during the study, they were excluded.

The results of this extensive study were noteworthy, to say the least. The authors stated:

“Exposure to vitamin D supplementation was associated with a 40% lower dementia incidence rate than no exposure, providing strong support for supplementation. The results were consistent across three vitamin D formulations.” 

Further, the association with lower dementia risk in the vitamin D users was seen in both sexes as well as in those who were carriers of the APOE ε4 gene, known to be associated with increased Alzheimer’s risk, although these relationships were somewhat less pronounced.

Now, some would argue that there is still no solid support for recommending vitamin D supplementation as a tool to help keep the brain healthy. I respectfully disagree, and have supported vitamin D supplementation for the last 15 years. Indeed, as the authors of this study concluded:

“…our findings implicate vitamin D as a potential agent for dementia prevention and provide additional support for its use in at-risk individuals for AD dementia.”