Is Vitamin D Deficiency Linked to Alzheimer's
Disease and Vascular Dementia?
William B. Grant, Ph.D.
Journal of Alzheimer's Disease 17:1 (May 2009).

There are several risk factors for the development of Alzheimer's disease and
vascular dementia. Based on an increasing number of studies linking these risk
factors with Vitamin D deficiency, an article in the current issue of the Journal of
Alzheimer's Disease (May 2009) by William B. Grant, PhD of the Sunlight, Nutrition,
and Health Research Center (SUNARC) suggests that further investigation of possible
direct or indirect linkages between Vitamin D and these dementias is needed.

Low serum levels of 25-hydroxyvitamin D [25(OH)D] have been associated with
increased risk for cardiovascular diseases, diabetes mellitus, depression, dental
caries, osteoporosis, and periodontal disease, all of which are either considered risk
factors for dementia or have preceded incidence of dementia. In 2008, a number of
studies reported that those with higher serum 25(OH)D levels had greatly reduced
risk of incidence or death from cardiovascular diseases.

Several studies have correlated tooth loss with development of cognitive impairment
and Alzheimer's disease or vascular dementia. There are two primary ways that
people lose teeth: dental caries and periodontal disease. Both conditions are linked
to low vitamin D levels, with induction of human cathelicidin by 1,25-dihydroxyvitamin
D being the mechanism.

There is also laboratory evidence for the role of vitamin D in neuroprotection and
reducing inflammation, and ample biological evidence to suggest an important role for
vitamin D in brain development and function.

Given these supportive lines of evidence, Dr. Grant suggests that studies of incidence
of dementia with respect to prediagnostic serum 25(OH)D or vitamin D
supplementation are warranted. In addition, since the elderly are generally vitamin D
deficient and since vitamin D has so many health benefits, those over the age of 60
years should consider having their serum 25(OH)D tested, looking for a level of at
least 30 ng/mL but preferably over 40 ng/mL, and supplementing with 1000-2000
IU/day of vitamin D3 or increased time in the sun spring, summer, and fall if below
those values.

Writing in the article, Dr. Grant states, "There are established criteria for causality in a
biological system. The important criteria include strength of association, consistency
of findings, determination of the dose-response relation, an understanding of the
mechanisms, and experimental verification. To date, the evidence includes
observational studies supporting a beneficial role of vitamin D in reducing the risk of
diseases linked to dementia such as vascular and metabolic diseases, as well as an
understanding of the role of vitamin D.
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