Low vitamin D serum levels as risk factor of Alzheimer’s disease: a systematic review and meta-analysis

Abstract

Past literatures have reported that changes in serum vitamin D levels are related to cognitive dysfunctions, such as dementia, including Alzheimer’s disease (AD). However, these past studies vary in results on whether vitamin D levels correlated with the development of AD. This meta-analysis aimed to assess the associations between low vitamin D serum levels as risk factor of AD based on the latest evidence. We systematically searched Pubmed and additional references for relevant articles according to PRISMA guidelines from the beginning up to December 2022. The risk estimate of AD was determined using a pooled hazard ratio (HR) with 95% confidence intervals (CIs). five prospective trials and one cross-sectional study were analyzed. The meta-analysis showed that patients with low vitamin D serum levels (< 25 ng/ml) had an increased risk of developing AD compared to patients with normal vitamin D levels (≥ 25 ng/ml) (HR: 1.59, 95% CI: 1.09, 2.33, I 2=77%). Further research is required to provide evidence on whether maintaining sufficient vitamin D serum levels may lower the risk of AD.