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Vitamin D has been investigated in association with cognitive function in healthy and multimorbid elderly patients. Whether higher physiologic concentrations of vitamin D may be neuroprotective is not yet known. Epidemiological investigations have suggested a protective effect of physiologic vitamin D concentrations (circulating 25-hydroxyvitamin D) on neurocognitive dysfunction and cerebrovascular disease. Recent prospective studies have shown a beneficial association of vitamin D with a myriad of health conditions and suggest that vitamin D may be neuroprotective via vascular mechanisms. Whether vitamin D concentrations are a useful indicator for the identification and clinical management of dementia remains to be determined. On its own, physiological vitamin D status may be an important risk indicator for several comorbidities; however, further studies are required to determine if physiological vitamin D can be used as a biomarker in the clinical determination and disease management of dementia., (Copyright 2011 Prous Science, S.A.U. or its licensors. All rights reserved.)

Background: Vitamin D deficiency has potential adverse effects on neurocognitive health and subcortical function. However, no studies have examined the association between vitamin D status, dementia, and cranial MRI indicators of cerebrovascular disease (CVD)., Methods: Cross-sectional investigation of 25-hydroxyvitamin D [25(OH)D], dementia, and MRI measures of CVD in elders receiving home care (aged 65-99 years) from 2003 to 2007., Results: Among 318 participants, the mean age was 73.5 +/- 8.1 years, 231 (72.6%) were women, and 109 (34.3%) were black. 25(OH)D concentrations were deficient (<10 ng/mL) in 14.5% and insufficient (10-20 ng/mL) in 44.3% of participants. There were 76 participants (23.9%) with dementia, 41 of which were classified as probable AD. Mean 25(OH)D concentrations were lower in subjects with dementia (16.8 vs 20.0 ng/mL, p < 0.01). There was a higher prevalence of dementia among participants with 25(OH)D insufficiency (< or =20 ng/mL) (30.5% vs 14.5%, p < 0.01). 25(OH)D deficiency was associated with increased white matter hyperintensity volume (4.9 vs 2.9 mL, p < 0.01), grade (3.0 vs 2.2, p = 0.04), and prevalence of large vessel infarcts (10.1% vs 6.9%, p < 0.01). After adjustment for age, race, sex, body mass index, and education, 25(OH)D insufficiency (< or =20 ng/mL) was associated with more than twice the odds of all-cause dementia (odds ratio [OR] = 2.3, 95% confidence interval [CI] 1.2-4.2), Alzheimer disease (OR = 2.5, 95% CI 1.1-6.1), and stroke (with and without dementia symptoms) (OR = 2.0, 95% CI 1.0-4.0)., Conclusions: Vitamin D insufficiency and deficiency was associated with all-cause dementia, Alzheimer disease, stroke (with and without dementia symptoms), and MRI indicators of cerebrovascular disease. These findings suggest a potential vasculoprotective role of vitamin D.

Background: The objective of this study was to examine the association between 25-hydroxyvitamin D, 25(OH)D, and cognitive function., Methods: A cross-sectional investigation of 25(OH)D and cognition was completed in 377 black and 703 non-black (mainly Caucasian) elders (65-99 years) participating in the nutrition and memory in elders study. Participants underwent a comprehensive neuropsychological battery, and 25(OH)D concentrations were obtained., Results: More than 65% of elders had suboptimal 25(OH)D concentrations (< or =20 ng/mL or < or =50 nmol/L). Approximately 18% were deficient in 25(OH)D (<10 ng/mL or <25 nmol/L). After adjusting for age, sex, race, body mass index, education, center, kidney function, seasonality, physical activity, and alcohol use, 25(OH)D was associated with better performance on trails A (beta = -0.49, p < .03), trails B (beta = -0.73, p < .02), digit symbol (beta = 0.19, p < .001), matrix reasoning (beta = 0.04, p < .02), and block design (beta = 0.07, p < .04) tests. Associations remained after adjustment for homocysteine, apoE4 allele, plasma B vitamins, and multivitamin use (y/n). 25(OH)D concentrations >20 ng/mL were associated with better performance on tests of executive function, including trails A (80.5 vs 95, p < .05), trails B (205s vs 226s, p < .05), matrix reasoning (7.8 vs 7.0, p = .03), and digit symbol (31.5 vs 37, p < .01). There were no associations between 25(OH)D and memory tests. Factor analysis yielded factors for memory, executive function, and attention/processing speed. After adjustment, 25(OH)D was associated with the executive function (beta = 0.01, p < 0.01) and attention/processing speed factors (beta = 0.01, p = .03), but not the memory factor (beta = -0.001, p = 0.65)., Conclusions: 25(OH)D was positively associated with cognitive performance, particularly with measures of executive function in this elderly population.

A preponderance of evidence supports a role for vitamin D beyond the classical function in mineral homeostasis. Epidemiologic investigations have revealed a beneficial role of vitamin D in muscle function, cardiovascular health, diabetes, and cancer prevention. More recently, studies have suggested a potential beneficial role of vitamin D in cognitive function. Vitamin D exhibits functional attributes that may prove neuroprotective through antioxidative mechanisms, neuronal calcium regulation, immunomodulation, enhanced nerve conduction and detoxification mechanisms. Compelling evidence supports a beneficial role for the active form of vitamin D in the developing brain as well as in adult brain function. The vitamin D receptor and biosynthetic and degradative pathways for the hydroxylation of vitamin D have been found in the rodent brain; more recently these findings have been confirmed in humans. The vitamin D receptor and catalytic enzymes are colocalized in the areas of the brain involved in complex planning, processing, and the formation of new memories. These findings potentially implicate vitamin D in neurocognitive function.