Key PointsQuestionAre changes in adipokines, inflammatory factors, mood, and physical activity associated with cognitive improvement 6 months after bariatric surgery?FindingsIn this cohort study of 156 participants with severe obesity who underwent bariatric surgery, 43.8% of the participants experienced overall cognitive improvement 6 months after surgery. This group had lower C-reactive protein and leptin levels and fewer depressive symptoms 6 months after surgery compared with the group of participants who did not show cognitive improvement.MeaningThis study suggests that reduced C-reactive protein and leptin levels, as well as fewer depressive symptoms, might partly explain the mechanisms behind cognitive improvement after bariatric surgery.