Cognitive Impairment in Older Persons Linked to Vitamin D Deficiency

By Kristina Fiore, Staff Writer, MedPage Today Reviewed by Dori F. Zaleznik, MD; Associate Clinical Professor of Medicine, Harvard Medical School, Boston. A low level of vitamin D in older patients is associated with a higher risk of cognitive impairment, researchers here said.

Those with the lowest levels were more than twice as likely to have cognitive impairment (P<0.001),>Journal of Geriatric Psychology and Neurology.

"Our results suggest that high levels of serum 25-hydroxyvitamin D are associated with lower odds of cognitive impairment," the researchers said.

As patients age, however, the capacity of their skin to absorb vitamin D from sunlight decreases, often requiring they obtain it from other sources, they said.

Evidence from in vitro and animal studies suggests vitamin D may be neuroprotective, but there is a "paucity of reliable evidence" from clinical and population studies, the researchers said.

So to examine the association between serum vitamin D and cognitive impairment, the researchers conducted a cross-sectional study of 1,766 persons 65 and older in the Health Survey for England 2000.

The researchers found that vitamin D levels were higher in those with normal cognition than in those who were cognitively impaired.

About half of patients with cognitive impairment had the lowest serum levels of the vitamin.

In a multivariate analysis, those with the lowest levels of vitamin D were 2.3-fold more likely to be cognitively impaired than those with the highest levels (95% CI 1.4 to 3.8, P=0.001).

In that analysis, the association was stronger in men, which may be attributable to differences in BMI, the researchers said.