Bariatric Surgery and Neurologic Diagnoses in Adults With Obesity: A Retrospective Cohort Study

Background and Aims: Obesity, the gut–brain axis, and bariatric surgery may influence neurologic disease risk; however, population-level data are limited. This study compared the incidence of Alzheimer’s disease, Parkinson’s disease, multiple sclerosis, and epilepsy in adults with obesity who underwent bariatric surgery versus those who did not. Methods This was a retrospective cohort study using the TriNetX Global Collaborative Network. Adults with overweight/obesity (ICD-10 E66) were assigned to Surgical (RYGB or SG) or Non-Surgical cohorts. 1:1 propensity score matching was performed on demographic and clinical covariates. Risk ratios, risk difference, and hazard ratios were estimated for incident diagnoses (ICD-10: AD G30; PD G20; MS G35; epilepsy G40). Results In matched cohorts (n = 776,800; 388,400 per group), bariatric surgery was associated with a lower incidence of neurologic disease (0.6% vs 0.9%; RR 0.68, 95% CI 0.64–0.71; HR 0.71, 95% CI 0.68–0.75; p < 0.001). Risk reductions were also observed for Alzheimer’s disease (RR 0.64; HR 0.70), Parkinson’s disease (RR 0.80; HR 0.86), multiple sclerosis (RR 0.73; HR 0.76), and epilepsy (RR 0.64; HR 0.66). Relative risk reductions ranged from 20% to 36%, greatest for Alzheimer’s disease and epilepsy. Conclusion Among adults with obesity, bariatric surgery was associated with a lower recorded incidence of AD, PD, MS, and epilepsy. While these findings align with biologically plausible immunometabolic and gut–brain mechanisms, residual confoundings limit causal inference. Future research is needed to confirm causality.