Serum Uric Acid and the Risk of Dementia: A Systematic Review and Meta-Analysis

This meta-analysis aimed to evaluate the relationship between serum uric acid (UA) and the risk of dementia and its subtypes. Embase, PubMed, and Web of Science were searched from inception to July 2020. Random-effect models were employed to analyze the standard mean difference (SMD) with the corresponding 95% confidence intervals (CI). Twenty-three eligible studies involving 5,575 participants were identified. The overall results showed lower levels of UA in dementia relative to non-dementia controls [SMD = -0.32 (-0.64; -0.01) = 0.04]. The subgroup analysis of the type of dementia demonstrated a significant association of UA with Alzheimer's disease (AD) [SMD = -0.58 (-1.02; -0.15) = 0.009] and Parkinson's disease with dementia (PDD) [SMD = -0.33 (-0.52; -0.14) = 0.001] but not with vascular dementia (VaD). The stratification analysis of the concentrations of UA revealed that the UA quartile 1-2 was negatively correlated with dementia and neurodegenerative subtypes ( < 0.05), whereas a positive correlation of UA quartile 4 with dementia was noted ( = 0.028). Additionally, the meta-regression analysis on confounders showed that not age, body mass index, diabetes mellitus, hypertension, or smoking but education ( = 0.003) exerted an influence of the UA in the risk estimate of dementia. Low concentrations of UA (< 292 μmol/L or 4.91 mg/dL) is a potential risk factor for AD and PDD but not for VaD. The mechanism of different concentrations of the UA in dementia needs to be confirmed through further investigation.