NEW ORLEANS—Vitamin D may modulate the course of neurologic diseases such as Alzheimer’s disease and amyotrophic lateral sclerosis (ALS), according to two studies presented at the 64th Annual Meeting of the American Academy of Neurology. Vitamin D deficiency may increase cognitive decline associated with Alzheimer’s disease, and vitamin D supplements could provide benefits for patients with Alzheimer’s disease or ALS, researchers reported.
Previous research has suggested that vitamin D protects the nerves in various ways. Vitamin D simultaneously targets factors that lead to neurodegeneration, including immunoregulatory, antioxidant, and anti-ischemic factors; neurotrophic factors; and acetylcholine neurotransmitters. Vitamin D also helps to clear amyloid-β peptide and to prevent hyperparathyroidism.
Vitamin D and Alzheimer’s Disease
Amie Peterson, MD, a neurologist at Oregon Health and Science University in Portland, and colleagues tested plasma vitamin D levels in 40 nondemented subjects to determine whether vitamin D status predicted cognitive function or CSF biomarker findings in persons at risk of Alzheimer’s disease. All participants (26 women) were older than 60 (mean age, 71) and had first-degree relatives with Alzheimer’s disease. Subjects donated CSF for biomarker studies and underwent cognitive testing, including Mini-Mental State Examination (MMSE) and digit span.
Four of the 40 subjects had sufficient plasma vitamin D concentrations (>40 ng/mL). Seventeen participants were deficient in vitamin D (<30 ng/mL), and 19 had insufficient vitamin D (30 to 40 ng/mL). Plasma vitamin D levels were inversely correlated with age. After adjusting for age, Dr. Peterson’s group found that vitamin D levels were correlated with MMSE score and Backward Digit-Span Task score. Plasma vitamin D, however, was not correlated with CSF amyloid-β1-42, tau, or phosphorylated tau levels.
Vitamin D levels decline with age, and although they might modulate age-related cognitive decline, “reverse causation is also a possibility,” said Dr. Peterson. A vitamin D intervention trial could test this hypothesis.