Alzheimer’s disease (AD) is the most common form of dementia in the elderly individuals and is associated with progressive memory loss and cognitive dysfunction. A significant association between AD and low levels of vitamin D has been demonstrated.
Furthermore, vitamin D supplements appear to have a beneficial clinical effect on AD by regulating micro-RNA, enhancing toll-like receptors, modulating vascular endothelial factor expression, modulating angiogenin, and advanced glycation end products.
Vitamin D also exerts its effects on AD by regulating calcium-sensing receptor expression, enhancing amyloid-β peptides clearance, interleukin 10, downregulating matrix metalloproteinases, upregulating heme oxygenase 1, and suppressing the reduced form of nicotinamide adenine dinucleotide phosphate expression.
In conclusion, vitamin D may play a beneficial role in AD.
Calcitriol is the best vitamin D supplement for AD, because it is the active form of the vitamin D3 metabolite and modulates inflammatory cytokine expression. Therefore, further investigation of the role of calcitriol in AD is needed.
LUONG, K. V. Q., NGUY{ECIRCTILDE}N, L. T. H.
AMERICAN JOURNAL OF ALZHEIMER’S DISEASE AND OTHER DEMENTIAS28(2):126-136, 20131533-3175

Connie’s comments: Take your parents for a walk in the park with plenty of sunshine regularly. Vitamin D is needed in the absorption of many important essential nutrients needed by our body such as calcium and magnesium. Some of the calcium (TUMs) we ingested from other sources are not absorbed by the body or not in absorbable form that impedes absorption of other essential nutrients (Iron). Vit C, D and Calcium and Magnesium works in synergy when taken in the afternoon while iron is best taken during the morning and better from whole foods esp for the menopausal women.