Could Vitamin D Deficiency Hasten Cognitive Decline?

Vitamin D insufficiency is associated with greater declines in cognitive ability and episodic memory in older adults, according to a recent study.

In order to further examine the association between vitamin d status and cognitive function, researchers conducted a longitudinal multiethnic cohort study of 382 participants between 2002 and 2010.
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Participants’ vitamin D serum levels were measured at baseline, and at yearly follow-up visits.

Note: Vitamin D deficiency was defined as serum level less than 12 ng/mL, insufficient as 12 ng/mL to less than 20 ng/mL, adequate as 20 ng/mL to less than 50 ng/mL, and high as 50 ng/mL or higher.

At enrollement, 17.5% of the participants had dementia, 32.7% had mild cognitive impairment, and 49.5% had no cognitive impairment.

Overall, average levels of serum vitamin D were lower in the dementia group compared with those of individuals with mild cognitive impairment and healthy individuals. Further, the rates of decline in episodic memory and executive function in participants with vitamin D deficiency and those that were vitamin D insufficient were greater than those with adequate levels of serum vitamin D.

“Vitamin D insufficiency was associated with significantly faster declines in both episodic memory and executive function performance, which may correspond to elevated risk for incident [Alzheimer disease] dementia,” they concluded.

“Given that vitamin D insufficiency is medically correctable, well-designed clinical trials that emphasize enrollment of individuals of nonwhite race/ethnicity with hypovitaminosis D could be useful for testing the effect of VitD replacement on dementia prevention.”

—Michael Potts

Reference:

Miller JW, Harvey DJ, Beckett LA, et al. Vitamin d status and rates of cognitive decline in a multiethnic cohort of older adults. JAMA Neurol. [epub ahead or print September 14, 2015]. doi:10.1001/jamaneurol.2015.2115