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 postsurgery and determine the extent to which baseline brain activity predicts weight loss at 12-month postsurgery. 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-month post-SG. RESULTS: SG patients lost an average of 29.0% of their weight (percentage of total weight loss (%TWL)) at 12-month 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 (family-wise error (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 postsurgery weight loss. Replication in larger studies is necessary to determine true effect sizes for outcome prediction.

Relationships among 5-HTT genotype, life events and gender in the recognition of facial emotions.

Accumulating evidence has shown that a polymorphism in the promoter region of the serotonin-transporter (5-HTTLPR) modulates neural activation during the perceptual processing of emotional facial expressions. Furthermore, behavioral research has shown that attentional bias for negative information is increased in s allele carriers. We examined the interactions among 5-HTTLPR (including SNP rs25531), life events and gender on the detection of facial emotions. We found a main effect of genotype, as well as moderating effects of childhood emotional abuse (CEA) and recent life events (RLE). S homozygous participants recognized negative facial expressions at a lower intensity than the other genotype groups. This effect was more evident in female participants and in participants who had experienced life events. The 5-HTTLPR genotype affects facial emotional perception, a process which is linked to a neurobiological response to threat and vulnerability to emotional disorders.