Serum 25-hydroxyvitamin D concentration and cognitive impairment

Abstract

Vitamin D may be of interest in the prevention of cognitive impairment, though previous findings are inconclusive. Participants were 1766 adults aged 65 years and older from the Health Survey for England 2000, a nationally representative population-based study. Cognitive impairment was assessed using the Abbreviated Mental Test Score. The cross-sectional relation of serum 25-hydroxyvitamin D quartiles to cognitive impairment was modeled using logistic regression. In all, 212 participants (12%) were cognitively impaired. Odds ratios (95% confidence intervals) for cognitive impairment in the first (8-30 nmol/L), second (31-44 nmol/L), and third (45-65 nmol/L) quartiles of serum 25-hydroxyvitamin D compared with the fourth (66-170 nmol/L) were 2.3 (1.4-3.8), 1.4 (0.8-2.4), and 1.1 (0.6-1.9), after adjustment for age, sex, education, ethnicity, season of testing, and additional risk factors for cognitive impairment (P for linear trend = .001). Our data suggest low serum 25-hydroxyvitamin D is associated with increased odds of cognitive impairment.

Figure 1

Odds of cognitive impairment by quartiles of serum 25-hydroxyvitamin D [25(OH)D] for 1766 older persons. Bars indicate 95% confidence intervals. Cognitive impairment was defined as a score <8 on the Abbreviated Mental Test. Population weights are used to allow for the sampling design. Results are also adjusted for age, sex, education, ethnicity, season tested, current smoking status, alcohol consumption, psychiatric morbidity, impaired mobility, hypoalbuminemia, and medical history (stroke, heart disease, diabetes, and hypertension).