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Information on the latest vitamin D news and research.

Find out more information on deficiency, supplementation, sun exposure, and how vitamin D relates to your health.

Is D deficiency linked to risk of cognitive decline?

Dr. David J. Llewellyn and colleagues from all over the world recently conducted the first large longitudinal 6-year study on vitamin D and dementia. They studied 858 older adults, seeing if low 25(OH)D levels at baseline predicted the onset or worsening of dementia.

Llewellyn DJ, Lang IA, Langa KM, Muniz-Terrera G, Phillips CL, Cherubini A, Ferrucci L, Melzer D. Vitamin D and risk of cognitive decline in elderly persons. Arch Intern Med. 2010 Jul 12;170(13):1135-41.

They found that those who were severely deficient (<10 ng/ml) were 60% more likely over the six years to develop dementia compared to those with the highest vitamin D levels. Furthermore, at baseline, 16 patients with levels less than 10 ng/ml were demented compared to only one with levels above 30 ng/ml. Not enough patients had natural levels (50 ng/ml) to see how protective they were.

These results may be understatements as the usual overcorrections occurred. For example, obesity, smoking, sex, age, and impaired mobility are associated with both dementia and vitamin D deficiency, correcting for them will partially mask the vitamin D contribution and lower the positive findings of the study.

In spite of this, the authors stated, “This is the first prospective study to show that low levels of 25(OH)D are associated with elevated risk of cognitive decline.”

As we age, most of us fear losing our minds. Dementia is common in the older population, originally meaning madness, it is a serious loss of cognitive ability in a previously normal person, beyond what is from normal aging. Dementia is usually progressive, resulting in long-term mental decline and eventual severe loss of brain function.

Although dementia is far more common in the geriatric population, it can occur before the age of 65, in which case it is termed “early onset dementia.” A recent survey revealed that dementia is the second leading health concern after cancer. My mother, a math teacher, died of dementia and, for the last ten years of her life, had no idea who I was.

As for vitamin D’s beneficial role, the mechanism of action may be simple. At least one study has shown that activated vitamin D helps remove b-amyloid in mammalian brains, the major cause of dementia.

Mizwicki MT, Menegaz D, Zhang J, Barrientos-Durán A, Tse S, Cashman JR, Griffin PR, Fiala M. Genomic and nongenomic signaling induced by 1α,25(OH)2-vitamin D3 promotes the recovery of amyloid-β phagocytosis by Alzheimer’s disease macrophages. J Alzheimers Dis. 2012 Jan 1;29(1):51-62

If this is true, it may mean that vitamin D not only has a preventative effect in dementia, but also a possible treatment effect, if the brain is not permanently damaged. In such patients, I suggest high normal vitamin D levels, around 80 ng/ml, because of the importance of what is at stake, but don’t expect miracles. Again, and I can’t state this enough, remember all four co-factors, especially magnesium, usually 500 mg of magnesium citrate daily for adults.

  About: John Cannell, MD

Dr. John Cannell is founder of the Vitamin D Council. He has written many peer-reviewed papers on vitamin D and speaks frequently across the United States on the subject. Dr. Cannell holds an M.D. and has served the medical field as a general practitioner, emergency physician, and psychiatrist.

5 Responses to Is D deficiency linked to risk of cognitive decline?

  1. JBG says:

    It would be helpful to list here all four of the co-factors you consider to be important.

  2. Brant Cebulla says:

    Good call JBG,

    The four co-factors Dr Cannell feels are important are: magnesium, zinc, vitamin K and boron.

    See http://www.vitamindcouncil.org/about-vitamin-d/vitamin-d-cofactors/ for more information.

  3. Ian says:

    Brant, On the reference you gave about the co-factors the following was in the list:
    Vitamin A (coming soon)
    In what way is vit A a co-factor? Any refs?

    • Brant Cebulla says:

      The vitamin D receptor (activated by vitamin D metabolite) binds to the retinoid X receptor (activated by vitamin A metabolite) to upregulate or downregulate gene products.

      It is not known what the effect of nutrition is on this interaction, though one theory is that too much vitamin A and not enough vitamin D weakly stimulates this interaction compared to the right amounts.

  4. JBG says:

    Brant, in the list of co-factors you give above, and on the page about co-factors, it is vitamin K2 that is meant.

    The point is important because it IS K2 that is the important vitamin D co-factor, and because most people seeing the phrase “vitamin K” will think the vitamin having to do with blood coagulation that is obtained from green veggies is meant. Most people have never heard of K2, and a great many people are deficient in K2, perhaps more even than who are deficient in D, whereas probably most people have enough K1. Even the VDC discussion of vitamin K is confusing about K1 and K2.