Objective: To test the hypothesis that hypovitaminosis D is associated with a higher risk of cognitive decline over a 4.4-year follow-up in a large sample of older adults.
Methods: This research was part of the Progetto Veneto Anziani (Pro.V.A.), an Italian population-based cohort study of 1,927 elderly subjects. Serum 25-hydroxyvitamin D (25OHD) levels were measured at the baseline. Global cognitive function was measured with the Mini-Mental State Examination (MMSE); scores lower than 24 were indicative of cognitive dysfunction, and a decline of 3 or more points on the MMSE over the follow-up was considered as clinically significant. Analyses were adjusted for relevant confounders, including health and performance status.
Results: Participants with 25OHD deficiency (<50 nmol/L) or insufficiency (50-75 nmol/L) were more likely to have declining MMSE scores during the follow-up than those who were 25OHD sufficient (≥75 nmol/L). Among participants cognitively intact (baseline MMSE scores ≥24 and without diagnosis of dementia), the multivariate adjusted relative risk (95% confidence interval [CI]) of the onset of cognitive dysfunction was 1.36 (95% CI: 1.04-1.80; p = 0.02) for those with vitamin D deficiency and 1.29 (95% CI: 1.00-1.76; p = 0.05) for those with vitamin D insufficiency by comparison with individuals with normal 25OHD levels.
Conclusion: The results of our study support an independent association between low 25OHD levels and cognitive decline in elderly individuals. In cognitively intact elderly subjects, 25OHD levels below 75 nmol/L are already predictive of global cognitive dysfunction at 4.4 years.
© 2014 American Academy of Neurology.