Vitamin D in Relation to Cognitive Impairment, Cerebrospinal Fluid Biomarkers, and Brain Volumes

Background. Low vitamin D status is associated with poorer cognitive function in older adults, but little is known about the potential impact on cerebrospinal fluid (CSF) biomarkers and brain volumes. The objective of this study was to examine the relations between plasma 25-hydroxyvitamin D (25(OH)D) and cognitive impairment, CSF biomarkers of Alzheimer's disease (AD), and structural brain tissue volumes. Methods. A total of 75 patients (29 with subjective cognitive impairment, 28 with mild cognitive impairment, 18 with AD) referred to the Memory Clinic at Karolinska University Hospital, Huddinge, Sweden were recruited. Plasma 25(OH)D, CSF levels of amyloid beta (A beta(1-42)), total-tau, and phosphorylated tau, and brain tissue volumes have been measured. Results. After adjustment for several potential confounders, the odds ratios (95% confidence interval) for cognitive impairment were as follows: 0.969 (0.948-0.990) per increase of 1 nmol/L of 25(OH) D and 4.19 (1.30-13.52) for 24(OH) D values less than 50 nmol/L compared with values greater than or equal to 50 nmol/L. Adjusting for CSF A beta(1-42) attenuated the 25(OH) D-cognition link. In a multiple linear regression analysis, higher 25(OH)D levels were related to higher concentrations of CSF A beta(1-42) and greater brain volumes (eg, white matter, structures belonging to medial temporal lobe). The associations between 25(OH)D and tau variables were not significant. Conclusions. This study suggests that vitamin D may be associated with cognitive status, CSF A beta(1-42) levels, and brain tissue volumes.