Association Between a Body Shape Index and Epilepsy Among US Adults: Potential Indirect Pathway Through Depressive Symptoms

BACKGROUND: Epilepsy is a common and disabling brain disorder. Whether a body shape index (ABSI) is associated with epilepsy, and whether depressive symptoms may partly account for this association, remain unclear. METHODS: We analyzed 13,066 participants from the National Health and Nutrition Examination Survey 2013-2018. ABSI was calculated from waist circumference, weight, and height. Epilepsy was identified using prescription medication reason code G40 within the past 30 days. Depressive symptoms were assessed using Patient Health Questionnaire 9. Multivariate logistic regression was used to evaluate associations among ABSI, depressive symptoms, and epilepsy. Restricted cubic splines (RCSs) were applied to examine potential nonlinearity. An exploratory mediation analysis was performed to examine whether depressive symptoms may partly account for the observed association between ABSI and epilepsy. RESULTS: In the multivariate logistic regression analyses, higher ABSI was significantly associated with increased odds of both epilepsy (odds ratio [OR], 1.39; 95% confidence interval [CI], 1.12-1.71) and depressive symptoms (OR, 1.16; 95% CI, 1.08-1.24). Additionally, a positive association was also identified between depressive symptoms and epilepsy (OR, 2.28; 95% CI, 1.41-3.69). RCS analysis revealed that the associations between ABSI and both epilepsy and depressive symptoms were linear (both p for nonlinearity > 0.05). The exploratory mediation analysis indicated that depressive symptoms may partly account for the association between ABSI and epilepsy, accounting for 10.8% of the overall association. CONCLUSIONS: Higher ABSI was associated with a higher prevalence of epilepsy, and depressive symptoms may partly account for this relationship. These findings highlight the potential importance of integrating body composition and mental health perspectives in epilepsy epidemiology and may inform future prospective studies on modifiable metabolic and psychological factors.