Neural Predictors of 12-Month Weight Loss Outcomes Following Bariatric Surgery

BACKGROUND/OBJECTIVES: Despite the effectiveness of bariatric surgery, there is still substantial variability in long-term weight outcomes and few factors with predictive power to explain this variability. Neuroimaging may provide a novel biomarker with utility beyond other commonly used variables in bariatric surgery trials to improve prediction of long-term weight loss outcomes. The purpose of this study was to evaluate the effects of sleeve gastrectomy (SG) on reward and cognitive control circuitry post-surgery and determine the extent to which baseline brain activity predicts weight loss at 12-months post-surgery. SUBJECTS/METHODS: Using a longitudinal design, behavioral, hormone, and neuroimaging data (during a desire for palatable food regulation paradigm) were collected from 18 patients undergoing SG at baseline (<1 month prior) and 12-months post-SG. RESULTS: SG patients lost an average of 29.0% of their weight (% total weight loss, %TWL) at 12-months post-SG, with significant variability (range: 16.0–43.5%). Maladaptive eating behaviors (uncontrolled, emotional, and externally-cued eating) improved (p<0.01), in parallel with reductions in fasting hormones (acyl ghrelin, leptin, glucose, insulin; p<0.05). Brain activity in the nucleus accumbens (NAcc), caudate, pallidum, and amygdala during desire for palatable food enhancement vs. regulation decreased from baseline to 12-months [p(FWE)<0.05]. Dorsolateral and dorsomedial prefrontal cortex activity during desire for palatable food regulation (vs. enhancement) increased from baseline to 12-months [p(FWE)<0.05]. Baseline activity in the NAcc and hypothalamus during desire for palatable food enhancement was significantly predictive of %TWL at 12-months [p(FWE)<0.05], superior to behavioral and hormone predictors, which did not significantly predict %TWL (p>0.10). Using stepwise linear regression, left NAcc activity accounted for 54% of the explained variance in %TWL at 12-months. CONCLUSIONS: Consistent with previous obesity studies, reward-related neural circuit activity may serve as an objective, relatively robust predictor of post-surgery weight loss. Replication in larger studies is necessary to determine true effect sizes for outcome prediction.