ASK THE DOCTOR: Are there Vitamin D Deficiency and cognitive associations?
Recent research once again confirms that cognitive decline is associated with Vitamin D deficiency in older adults. A recent study of 382 men and women through the Alzheimer’s Disease Center in Sacramento, California found that Vitamin D deficient individuals suffered cognitive decline at a rate of two to three times faster than those who had adequate serum vitamin D levels, which means that it took only two years for the deficient individuals to decline as much as their counterparts with adequate Vitamin D did during the entire five-years of the study.1 Those with inadequate levels of vitamin D lost episodic memory and executive (decision making) function more quickly. Previous studies have also shown that inadequate Vitamin D is associated with lower scores on mental status exams2,3 and with cognitive decline6 in older adults.
“We expected to see declines in individuals with low vitamin D status,” said Charles DeCarli, the Director of the Alzheimer’s Disease Center that ran the study. “What was unexpected was how profoundly and rapidly it impacts cognition.”
Previous research has suggested that low levels of vitamin D might be a factor in cognitive decline and Alzheimer’s disease, and while this study showed a correlation of low Vitamin D to cognitive decline, it did not answer why, or how Vitamin D may be protective. However, there are multiple studies showing that Vitamin D is correlated with neuroprotective functions in the brain. A review article “Vitamin D and Neurocognitive Function” published in Clinical Interventions in Aging documents that “there is strong evidence that 1,25(OH)2D contributes to neuroprotection by modulating the production of nerve growth, decreasing L-type calcium channel expression, regulating the toxicity of reactive oxygen species, and neurotrophic factors such as nerve growth factor, glial cell-derived neurotrophic factor, and nitric oxide synthase. Furthermore, vitamin D and its metabolites are involved in other neuroprotective mechanisms including amyloid phagocytosis and clearance, and vasoprotection.” 4
This article includes 147 published citations of basic science research on Vitamin D and cognitive function. Read more on this article here.
Known risk factors for cognitive impairment include:
- lack of exercise
- a diet high in animal fats, or low in vegetables and fish
The evidence that Vitamin D deficiency should be added to this list continues to grow. It should be noted that the studies we’ve cited typically use a level of 20 ng/ml as being adequate, while many Vitamin D experts and clinical lab standards call for a minimum of 30 ng/ml, and up to 50-70 ng/ml are more reasonable “adequate” and “optimal” levels, respectively. It is advisable for all adults, especially those with cognitive challenges, to have their levels checked and augmented as indicated.
- Charles DeCarli, MD et al. Vitamin D Status and Rates of Cognitive Decline in a Multiethnic Cohort of Older Adults. JAMA Neurology, September 2015 DOI: 10.1001/jamaneurol.2015.2115
- Przybelski, R. J. Binkley, N. C. Is vitamin D important for preserving cognition? A positive correlation of serum 25-hydroxyvitamin D concentration with cognitive function. Arch Biochem Biophys. 2007 Apr 15; 460 (2): 202-5.
- Oudshoorn, C. Mattace-Raso, F. U. van der Velde, N. Colin, E. M. van der Cammen, T. J. Higher serum vitamin D3 levels are associated with better cognitive test performance in patients with Alzheimer’s disease. Dement Geriatr Cogn Disord. 2008; 25 (6): 539-43.
- Vitamin D and neurocognitive function. Mathias Schlögl and Michael F Holick Clin Interv Aging. 2014; 9: 559–568. Published online 2014 Apr 2.
- Seamans, K. M. Hill, T. R. Scully, L. Meunier, N. Andrillo-Sanchez, M.
- Polito, A. Hininger-Favier, I. Ciarapica, D. Simpson, E. E. Stewart-Knox, B. J. O’Connor, J. M. Coudray, C. Cashman, K. D. Vitamin D status and measures of cognitive function in healthy older European adults. Eur J Clin Nutr. Aug 11
- Buell, J. S. Scott, T. M. Dawson-Hughes, B. Dallal, G. E. Rosenberg, I. H. Folstein, M. F. Tucker, K. L. Vitamin D is associated with cognitive function in elders receiving home health services. J Gerontol A Biol Sci Med Sci. 2009 Aug; 64 (8): 888-95.