Executive control circuitry differentiates degree of success in weight loss following gastric-bypass surgery

Abstract

Objective: While overall success rates of bariatric surgery are high, approximately 20% of patients either regain or never lose the expected amount of weight. The purpose of this study was to determine whether, after gastric-bypass surgery, the degree of weight loss can be differentiated based on the neural response to food cues.

Design and methods: In this functional MRI study, 31 post-surgical patients viewed food and neutral images in two counterbalanced runs during which they were either instructed to "crave" or to "resist" craving. The neural response to food cues was assessed within and between runs for all participants, and further analyzed between more successful (n = 24) and less successful (n = 7) groups. More successful was defined by meeting 50% excess weight loss.

Results: Overall, instructions to "crave" elicited significant activity in the dorsomedial prefrontal cortex (PFC) whereas "resist" elicited significant activity in the dorsolateral PFC (DLPFC). Between groups there was no brain difference when instructed to "crave." The more successful participants however had significantly more activity in the DLPFC when instructed to "resist."

Conclusions: These findings suggest that the ability to mobilize neural circuits involved in executive control post-gastric-bypass surgery may be a unique component of successful outcome post-surgery.

FIGURE 1

Brain response to “craving” appetitive food cues. The data in this figure include statistical maps of the brain regions significantly activated when viewing food cues relative to non-food cues when the participants were instructed to “Crave.” Brain regions with elevated activity to the food cues (red color map and depressed activity to the food cues (blue color map) relative to neutral are displayed (cluster-wise P < 0.05, uncorrected). The coordinates above the coronal slices refer to the anterior–posterior dimension of the standardized MNI template. They are displayed as white lines on the sagittal section for further reference. R = right hemisphere, L = left hemisphere.

FIGURE 2

Brain response to “resisting” appetitive food cues. The data in this figure include the statistical maps of the brain regions significantly activated when viewing food cues relative to non-food cues when the participants were instructed to “Resist” the cues. Brain regions with elevated activity to the food cues (red color map) and depressed activity to the food cues (blue color map) relative to neutral are displayed (cluster-wise P < 0.05, uncorrected). The coordinates above the coronal slices refer to the anterior–posterior dimension of the standardized MNI template. They are displayed as white lines on the sagittal section for further reference. R = right hemisphere, L = left hemisphere.

FIGURE 3

Brain response to “Resist”: More successful greater than less successful. This figure displays the region with significantly higher activation (left dorsolateral prefrontal cortex) in the “more successful” group relative to the “less successful” group when instructed to resist the urge to crave in response to food cues (cluster-wise P < 0.05, uncorrected).