Correlation between serum 25-hydroxyvitamin D concentrations and regional cerebral blood flow in degenerative dementia

Abstract

Chronic low serum vitamin D concentrations are common among the elderly. Recent studies have suggested that its metabolite, 25-hydroxyvitamin D (25-OHD), might be important for preserving cognitive functions through specific brain protective effects. However, this hypothesis is still under discussion. The aim of this study was to assess the correlation between serum 25-OHD concentrations and regional cerebral blood flow in neurodegenerative diseases such as Alzheimer's disease (AD) and dementia of Lewy bodies (DLB). Radionuclide brain single-photon emission computed tomography/computed tomography (SPECT/CT) images and 25-OHD dosage in noninstitutionalized patients were obtained within 14 days. SPECT/CT examination was carried out using technetium-99m-ethyl cysteinate dimer in 20 consecutive patients (12 AD and eight DLB). Reconstructed images were spatially normalized using Statistical Parametric Mapping version 5 software to a default SPECT template. Voxel-based multiple regression correlation analyses, with age and mini mental state examination scores as confounding factors, were carried out. Findings were considered significant for a threshold P-value less than 0.01 (corrected at cluster level). A positive correlation was found between 25-OHD concentrations and regional cerebral blood flow in the left precuneus cortex (Talairach coordinates: -14, -42, 63) in AD patients. No correlation was detected in DLB patients. The results of this study confirm the relationship between 25-OHD concentrations and AD and therefore underline the hypothesis of a potential neuroprotective effect against brain degeneration. These encouraging findings need to be confirmed by larger prospective correlation series.