Retrospective assessment of time-dependent depression risk following epilepsy diagnosis in South Korea

This study aimed to assess the long-term risk for depression in individuals with epilepsy, identify time-specific risk patterns, and evaluate high-risk subgroups in a nationwide cohort from South Korea. This nationwide retrospective matched cohort study analyzed data from 2,267 patients with epilepsy and 22 670 age- and sex-matched controls retrieved from the Korean National Health Insurance Service cohort (2002-2013) were analyzed. KCD-8 codes (F32 and F33) were used as depression markers and time-stratified Cox proportional hazards models were employed to calculate the adjusted hazard ratios (aHRs) for depression over 10 years, adjusting for demographic and clinical covariates. The incidence rate (IR) of depression was 43.23 per 1,000 person-years in the epilepsy group compared to 14.30 in the controls (IRR = 3.02). Depression risk was highest in the first 0-2 years post-diagnosis (aHR = 3.32) and increased again at 8-10 years (aHR = 2.82). Men (IRR = 3.52) and individuals aged <60 years (IRR = 3.66) also demonstrated elevated IRRs. Smoking, low BMI, and high income were significant additional risk factors. Epilepsy substantially increases the long-term risk of depression, particularly during the early and late post-diagnosis periods and our findings underscore the need for systematic mental health screenings.