New study confirms the association between vitamin D and dementia

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Photo by Colin Dunn, CC-BY-2.0, via flickr

Photo by Colin Dunn, CC-BY-2.0, via flickr

The journal Neurology published an article describing the results of a study that confirmed a strong association between low levels of vitamin D and increased risk of dementia and Alzheimer’s disease in elderly people in the U.S. Here’s a breakdown of the research.


There is a lot of interest in understanding the impact of vitamin D levels in people with Alzheimer’s disease and other dementias. First off, vitamin D production occurs in several brain regions and there are vitamin D receptors throughout the brain, including the hippocampus, which is an important brain region for memory function. Vitamin D has been linked to clearance of amyloid plaques and to inflammatory processes in the brain related to amyloid. Vitamin D has also been linked to problems with blood vessels in the brain and other cerebrovascular pathology, which may be related to Alzheimer’s. Lastly, high rates of vitamin D deficiency are seen older adults.

The main sources of vitamin D are exposure of skin to sunlight; foods such as fatty fish (salmon, tuna), egg yolks, beef or calf liver and cheese; and dietary supplements. Vitamin D levels are easily evaluated through a standard blood draw done in a doctor’s office, similar to cholesterol tests.

The claim

Vitamin D deficiency is associated with a substantially increased risk of all-cause dementia and Alzheimer’s.

The methodology

This observational study looked at vitamin D levels in 1,658 people age 65+ who were free from dementia, cardiovascular disease, and stroke when they submitted blood samples for the Cardiovascular Health Study between 1992–1993 and 1999. The study participants were later tested for levels of vitamin D and evaluated for Alzheimer’s disease and other dementias.

  • During the study, 171 participants developed dementia, including 102 cases of Alzheimer’s.
  • Compared to participants with normal levels of vitamin D, those with low levels of vitamin D had a 53% increased risk of developing dementia, and those severely deficient of vitamin D had a 125% increased risk.
  • Those with low levels of vitamin D had a 69% increased risk of Alzheimer’s; those severely deficient had a 122% increased risk of Alzheimer’s.

Beyond the headline

Although this is not a new finding, the study does offer large-scale confirmation of a known association between vitamin D and dementia. It is important to note, however, that the study shows a correlation between vitamin D levels and Alzheimer’s disease and dementia; it does not show that low levels of vitamin D causes Alzheimer’s or dementia. It may be that having dementia causes vitamin D levels to go down, or there may be a third factor that affects both vitamin D levels and dementia risk. Observational studies such as this one uncover these associations, which then can be investigated further in other kinds of research, such as clinical trials.

The bottom line

It would be wonderful if addressing a single issue like vitamin D deficiency could delay or prevent Alzheimer’s disease. It would be simple, inexpensive, alleviate much suffering and heartache, and greatly reduce healthcare costs. However, Alzheimer’s and other brain diseases are very complex, and it will most likely require a combination of factors to influence your risk for dementia.
As a next step in the scientific process, we’d like to see clinical trials – where levels of vitamin D are changed in one study group but not in another – to investigate whether increasing vitamin D in people with low levels can delay or prevent Alzheimer’s.

The Alzheimer’s Association is pleased to have provided funding for this research and look forward to seeing more studies on vitamin D that will further our understanding of its relationship to Alzheimer’s disease.

Helpful information related to this story

More research stories by Dr. Edgerly
Read the article in Neurology
The Alzheimer’s Association’s Research page
Alzheimer’s disease risk factors

10 Responses

  1. This certainly was a compelling next step for this research, and hopefully it means that more people will become aware of how important vitamin D really is. I like your recommendation for what they could test in the phase of this process. However, knowing how complex this disease is, I have a strong feeling the next answer will not be this simple.

  2. Craig says:

    What information exists that Nicotinamide Riboside my help prevent Alzheimer’s Disease? The research of Doctor Sinclair at Harvard has been one of the leaders in this research.

  3. Craig says:

    Has NiaGen- Nicotinamide Riboside been found to be effective in preventing Alzheimer’s Disease ?

  4. whcrandall says:

    What is an adequate level of D-3?

  5. Larry says:

    Are there any Alzheimer study groups in states such as Washington State that have a lower level of sunshine in comparison to states with higher levels of sunshine like California or Arizona? Vitamin D test results in Washington state show low vitamin D levels is prevalent.

  6. Olga Rust says:

    IF someone is 59 years old & has been diagnosed with Alzheimer, is it a possibility to reverse it?

    • pguinto says:

      Hi Olga, currently there is no cure for Alzheimer’s although there are some drugs which help with symptoms. There are many trials taking place for people who have developed Alzheimer’s, particularly for those who are diagnosed early. Our helpline is here 24 hours a day at 800.272.3900 to answer any questions you have.

  7. Kraig Byrnes says:

    Great study! One large step for mankind!

  1. August 16, 2015

    […] care of them. Although not fully confirmed, it is suspected that there is a relationship between vitamin D and dementia. One of the reasons is because the production of vitamin D occurs in several areas in the brain. […]

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