Bidirectional influences between seizures and dementia: A systematic review and meta-analysis

Objectives: Dementia and seizures often co-exist, but the association between these two disorders is not well established. Therefore, this systematic review and meta-analysis aimed to clarify the relationship between seizures and dementia. Methods: The PubMed, EMBASE, CBM, and CNKI databases were used to search for relevant publications from inception to August 25, 2021. Data extraction was performed by two authors independently. The random-effects model was adopted to evaluate the pooled estimates. Results: Two nested case-control studies and 18 cohort studies were included in the meta-analysis. Seizures were associated with the development of dementia and Alzheimer's disease (AD), and the pooled relative risk (RR) was 2.51 [95% confidence intervals (CI) = 1.87-3.36, p < 0.001] and 1.61 (95% CI = 1.42-1.82, p < 0.001), respectively. Pooled RR estimating the effect of dementia on seizures risk was 3.68 (95% CI = 3.05-4.44, p < 0.001). In addition, the pooled effect size of dementia on epilepsy risk was 3.02 (95% CI = 2.16-4.23, p < 0.001). The subgroup analyses suggested that vascular risk factors could confound the associations between these two disorders. Seizures might independently and significantly increase the risk of dementia, and in turn, dementia might predispose an individual to a higher risk of seizures. Conclusions: These results suggested that dementia and seizures share common pathogenesis and might be treated with similar preventive treatment measures. Vascular changes in patients with dementia or seizures should also be examined.