Background: This study aimed to compare the risk of dementia between exposed to allopurinol and not exposed to allopurinol in persons who had gout and/or hyperuricemia.

Methods: The meta-analysis was conducted to select case-control research written in English through the help of PubMed and Web of Science. The pooled odds ratio (OR) with 95% confidence interval based on the fixed-effect model was applied to compare the allopurinol exposure among cases (subjects with dementia) and controls (subjects without dementia).

Results: A total of 4 case-control studies relating the allopurinol exposure to the risk of dementia were identified. The study duration was from 9 to 14 years. The number of study persons was from 3148 to 137,640. The male percentage of study subjects was from 36.9 to 62.5. The mean age of study persons was from 72.3 to 78.7 years. Overall, the odds of the allopurinol exposure among cases were lower than the odds of the allopurinol exposure among control subjects (OR = 0.91, 95% confidence interval = 0.87-0.95, P < .001). The heterogeneity between these eligible studies was low (I² = 0%). The sensitivity analysis revealed that after excluding the studies with concern, the pooled OR did not achieve statistical significance.

Conclusions: This is the first meta-analysis to report that there is a negative relationship between the allopurinol exposure and the risk of dementia. Although the results favor the hypothesis, currently it is unable to draw strong conclusions about the protective effect of allopurinol against dementia due to inclusion of only a few eligible studies. Randomized controlled trials are needed to explore the relationship between allopurinol exposure and the probability of dementia.