The impact of inflammatory bowel disease on dementia risk: a current systematic review and meta-analysis

Emerging evidence indicates that inflammatory bowel disease (IBD) and dementia may share underlying pathological mechanisms and risk factors. However, the association between a prior IBD diagnosis and the subsequent risk of dementia remains largely unexplored. We conducted a comprehensive search of PubMed, Embase, and the Cochrane Library up to February 4, 2025, without language restrictions. Two reviewers independently extracted data and evaluated methodological quality and risk of bias. Observational studies comparing dementia risk in IBD and non-IBD populations were included. Pooled effect estimates for odds ratios (OR) were calculated using random-effects models. A total of 10 population-based studies, involving 7,895,339 participants (269,387 with IBD), were included. Meta-analysis of eight studies showed a significant association between IBD and dementia risk (OR 1.17, 95% CI: 1.08-1.27, P = 0.0001). However, IBD was not associated with an increased risk of Alzheimer's disease (AD) (OR 1.15, 95% CI: 0.98-1.36, P = 0.09). Stratified analysis by IBD type revealed a positive association between both ulcerative colitis (UC) and Crohn's disease (CD) and dementia risk (UC: OR 1.15, 95% CI: 1.05-1.25, P = 0.002, I² = 81%; CD: OR 1.26, 95% CI: 1.11-1.43, P = 0.0003, I² = 53%). This study identifies a significant correlation between IBD and dementia, suggesting that IBD patients have an elevated risk of developing dementia. However, current evidence is insufficient to establish a causal relationship. Further research should explore whether effective IBD treatments can mitigate this risk and elucidate the underlying pathophysiological mechanisms connecting these conditions.