Vitamin D Deficiency Linked to Alzheimer's Disease
(HealthDay News) — Low concentrations of serum 25-hydroxyvitamin D (25[OH]D) may increase the risk of developing all-cause dementia and Alzheimer's disease, according to research published online Aug. 6 in Neurology.
Thomas J. Littlejohns, of the University of Exeter Medical School in the United Kingdom, and colleagues assessed the association between vitamin D concentrations and risk of incident all-cause dementia and Alzheimer's disease in 1,658 elderly ambulatory adults who were free from dementia, cardiovascular disease, and stroke at baseline.
The researchers found that at a mean follow-up of 5.6 years, compared with participants with sufficient 25(OH)D levels (≥50nmol/L), participants with severe 25(OH)D deficiency (<25nmol/L) and 25(OH)D deficiency (≥25–<50nmol/L) were at increased risk for incident all-cause dementia (multivariate-adjusted hazard ratios (HRs), 2.25 and 1.53, respectively). Compared with participants with sufficient 25(OH)D levels, participants with severe 25(OH)D deficiency and 25(OH)D deficiency also were at increased risk for incident Alzheimer's disease (multivariate-adjusted HRs, 2.22 and 1.69, respectively). Below a 25(OH)D threshold of 50nmol/L, the risk of all-cause dementia and Alzheimer's disease increased markedly.
"Our findings support the hypothesis that vitamin D may be neuroprotective and that 'sufficiency' in the context of dementia risk may be in the region of 50nmol/L," the authors write.