Effects of Vitamin D supplementation on cognitive function and blood Aβ-related biomarkers in older adults with Alzheimer's disease: A randomised, double-blind, placebo-controlled trial

Objective Our study aimed to assess the effect of a 12-month Vitamin D supplementation on cognitive function and amyloid beta (Aβ)-related biomarkers in subjects with Alzheimer's disease (AD). Methods This was a randomised, double-blind, placebo-controlled trial. 210 AD patients were randomly divided into intervention and control groups. Participants received 12-month 800 IU/day of Vitamin D or starch granules as placebo. Tests of cognitive performance and Aβ-related biomarkers were measured at baseline, 6 months and 12 months. Results Repeated-measures analysis of variance showed significant improvements in plasma Aβ42, APP, BACE1, APPmRNA, BACE1mRNA (p<0.001) levels and information, arithmetic, digit span, vocabulary, block design and picture arrange scores (p<0.05) in the intervention group over the control group. According to mixed-model analysis, Vitamin D group had significant increase in full scale IQ during follow-up period (p<0.001). Conclusions Daily oral Vitamin D supplementation (800 IU/day) for 12 months may improve cognitive function and decrease Aβ-related biomarkers in elderly patients with AD. Larger scale longer term randomised trials of Vitamin D are needed. Trial registration number ChiCTR-IIR-16009549. © Author(s) (or their employer(s)) 2019. No commercial re-use. See rights and permissions. Published by BMJ.