Vitamin D deficiency as a risk factor for dementia and Alzheimer's disease: an updated meta-analysis.
Level 3 - non-randomized controlled study
Systematic review of prospective cohort and cross-sectional studies
PubMed 31722673 · doi:10.1186/s12883-019-1500-6
What was done
Systematic review and meta-analysis searching PubMed, Cochrane Library, Embase, and reference lists through January 2019. The authors included 16 studies (12 prospective cohort studies and 4 cross-sectional studies) evaluating serum 25(OH)D levels and risk of dementia or Alzheimer's disease (AD). Pooled hazard ratios (HRs) and 95% confidence intervals (CIs) were calculated using random-effects models.
What was found
Vitamin D deficiency (< 20 ng/ml) was associated with an increased risk of dementia (HR 1.32, 95% CI: 1.16, 1.52) and AD (HR 1.34, 95% CI: 1.13, 1.60). In subgroup analyses, moderate deficiency (10–20 ng/ml) had pooled HRs of 1.48 (95% CI: 1.19, 1.85) for dementia and 1.51 (95% CI: 1.04, 2.18) for AD. Severe deficiency (< 10 ng/ml) had pooled HRs of 1.20 (95% CI: 0.99, 1.44) for dementia and 1.36 (95% CI: 1.01, 1.84) for AD.
Why it matters
This meta-analysis reinforces observational evidence linking low vitamin D status with a modest increase in dementia and Alzheimer's risk, though the association does not establish causality.
Limits
The analysis is based entirely on observational data, including four cross-sectional studies, which precludes causal inference. The abstract does not provide total participant sample size, heterogeneity metrics, or details on confounding adjustments.
Cited by
- partial Vitamin D deficiency is a significant risk factor for Alzheimer's disease and accelerates disease progression in people who already have Alzheimer's.