Irritable Bowel Syndrome Increases the Risk of Epilepsy: A Population-Based Study

An abnormal interaction in the brain–gut axis is regarded as the cause of irritable bowel syndrome (IBS). We attempted to determine the association between IBS and subsequent development of epilepsy. A total of 32,122 patients diagnosed with IBS between 2000 and 2011 were identified from the Longitudinal Health Insurance Database as the study cohort, and 63,295 controls were randomly selected from the insurants without IBS and frequency-matched according to age, sex, and index year as the comparison cohort. Both cohorts were followed up until the end of 2011 to measure the incidence of epilepsy. We analyzed the risks of epilepsy using Cox proportional hazards regression models. The IBS patients had greater cumulative incidence of epilepsy than the cohort without IBS (log-rank test, P < 0.001 and 2.54 versus 1.86 per 1000 person-years). The IBS cohort had a higher risk of epilepsy after adjusting for age, sex, diabetes, hypertension, stroke, coronary artery disease, head injury, depression, systemic lupus erythematosus, brain tumor, and antidepressants usage (adjusted hazard ratio [aHR]: 1.30, 95% confidence interval [CI]: 1.17–1.45). Stratified by the presence of other risk factors, the relative risk was also greater for patients with (aHR: 1.25, 95% CI: 1.10–1.41) or without other risk factors (aHR: 1.68, 95% CI: 1.35–2.10) in the IBS cohort than for those in the non-IBS cohort. The age-specific relative risk of epilepsy in the IBS cohort was greater than that in the non-IBS cohort for both 35 to 49 age group and 50 to 64 age group (age ≤ 34, aHR:1.31, 95% CI: 0.93–1.85; age 35–49, aHR: 1.43, 95% CI: 1.12–1.83; age 50–64, aHR: 1.56, 95% CI: 1.27–1.91). However, there was no difference between patients > 65 years with IBS and those without IBS (aHR: 1.11, 95% CI: 0.94–1.31). This population-based cohort study revealed that IBS increases the risk of developing epilepsy. However, IBS may be less influential than other risk factors. Further study is necessary to clarify whether IBS is a risk factor or an epiphenomenon for epilepsy development.