Vitamin D-related changes in intracranial volume in older adults: A quantitative neuroimaging study

a b s t r a c t Objectives: Vitamin D is involved in skeletal and brain health. Recently, serum 25-hydroxyvitamin D (25OHD) concentration was found to be inversely correlated with intracranial volume in younger adults. Since hypovitaminosis D is most common in older adults, our objective was to determine whether this inverse correlation between 25OHD concentration and intracranial volume also occurred in older adults. Study design: Cross-sectional study. Main outcome measures: One hundred and ten Caucasian older community-dwellers (mean, 71.7 ± 5.7 years; 45.5% female) received a blood test and an MRI of the brain at the same period. The intracra- nial volume and the subvolumes of cerebrospinal fluid, total brain, infratentorial brain, supratentorial brain, total white matter, total gray matter, cortical gray matter and subcortical gray matter were mea- sured using FreeSurfer volumetry on T1-weighted images. Vitamin D insufficiency was defined as serum 25OHD < 50 nmol/L. Age, gender, body mass index, education level, use of vitamin D supplements, season of evaluation, serum concentrations of calcium and thyroid stimulating hormone were used as covariables in the analysis. Results: We found that participants with vitamin D insufficiency (n = 41) had greater intracranial vol- ume than those without (1555.0 ± 1379.2 cm3 versus 1488.0 ± 167.4 cm3, P = 0.033). Serum 25OHD