Examining the bidirectional longitudinal associations between body mass index and episodic memory following bariatric surgery

The relationship between obesity and episodic memory (i.e., conscious memory for specific events) is hypothesized to be bidirectional. Indeed, studies have shown that metabolic and bariatric surgery (MBS) is associated with episodic memory improvement, and better memory is associated with better postsurgical weight-loss outcomes. However, direct tests of the hypothesized bidirectional association between episodic memory and body mass index (BMI) in MBS are lacking, as few studies have employed repeated, prospective assessments of memory in conjunction with bidirectional modeling techniques. The present study used latent change score analysis to examine the bidirectional longitudinal associations between episodic memory and BMI in the 2 years following MBS. University hospital; public practice. Episodic memory function and BMI were assessed in adults prior to MBS, and at 1, 6, 12, 18, and 24-months postsurgery. A total of 124 participants (41% lost at 2-year follow-up) showed, on average, favorable weight-loss and episodic memory outcomes following MBS. Crucially, presurgery episodic memory predicted initial change in BMI at 1-month postsurgery, and postsurgery episodic memory at 1- and 6-months predicted change in BMI at 6- and 12-months postsurgery. No evidence was found for pre- and postsurgery BMI predicting changes in episodic memory. Results supported a unidirectional prospective relationship between episodic memory and weight change following MBS, such that better memory pre- and postsurgery predicted improved weight-loss outcomes. These findings highlight the likely importance of episodic memory function for weight change and support the potential benefit of targeting memory processes to improve weight-loss outcomes.