Vitamin D deficiency is associated with worse cognitive performance and lower bone density in older African Americans

Abstract

Background: Vitamin D deficiency is common in older adults and is more prevalent among persons with darker pigmented skin. The detrimental effects of vitamin D deficiency on the bone are widely known; however, recent data suggest that vitamin D deficiency may contribute to other disorders, including low mood, cognitive impairment, and impaired mobility.

Objective: The purpose of this study was to determine whether nonskeletal diseases such as depression, cognitive impairment, and physical disability, which have been associated with vitamin D deficiency, are more commonly seen in older African Americans.

Design: In a cross-sectional study of 60 older adults (30 African Americans and 30 European Americans), vitamin D status, cognitive performance, physical performance, and bone mineral density (BMD) were assessed. Differences between groups and differences between those with vitamin D deficiency and those with normal vitamin D levels were tested.

Results: African Americans had a lower mean 25-hydroxyvitamin D level (17.98 ng/ml; SD, 6.9) compared to European Americans (25.20 ng/ml; SD, 7.0; p < .0001). Participants with vitamin D deficiency performed worse on a measure of cognitive performance, the Short Blessed Test (10.87 vs 6.31; p = .016); the Physical Performance Test (PPT) (27.00 vs 28.96; p = .039); and had lower BMD (0.823 vs 0.914; p = .005) and t scores (-1.29 vs -0.72; p = .008) of the hip. Among African Americans, vitamin D deficiency was associated with worse cognitive performance and lower BMD of the hip.

Conclusions: Vitamin D deficiency in older African Americans was associated with worse cognitive performance and lower BMD of the hip.