Effect of vitamin D on cognitive function and white matter hyperintensity in patients with mild Alzheimer's disease

Aim To examine the effect of vitamin D level on cognitive function and white matter hyperintensity (WMH) in patients with mild Alzheimer's disease (AD). Methods We recruited patients with mild AD, and carried out clinical interviews, neuropsychological assessments, laboratory tests and brain magnetic resonance imaging. Results In total, 146 patients with mild AD (68 men, 78 women; mean age 79.1 ± 7.0 years; mean education 10.2 ± 4.3 years) were enlisted. The mean Mini‐Mental State Examination (MMSE) score was 21.0 ± 3.8. The 25‐hydroxy vitamin D (25[OH]D) level was correlated negatively with the WMH volume (β = −0.219, P = 0.004) after adjusting for age, sex, years of education, apolipoprotein ε4 allele status, seasons of blood sampling, hypertension, diabetes mellitus, hyperlipidemia, coronary heart disease and total brain volume. The 25(OH)D level was correlated positively with the MMSE score (β = 0.309, P