P.3.007 - Resting-state connectivity changes in self-control networks in obese before and after bariatric surgery compared to lean

Abstract

Background/aims Obesity remains a major global challenge that is a risk factor for various diseases and one of the leading causes of preventable death. Currently, one of the most successful weight loss interventions is bariatric surgery, which triggers substantial weight loss and restores metabolic balance in the patient [1]. In this project, we investigated whether bariatric surgery impacts resting state activity in brain regions related to dietary self-control and whether there are group differences between obese and lean participants. Participants 16 morbidly obese (BMI: 36.5-63.5 kg/m2, mean±SD: 45.6±5.2) and 40 normal-weight (BMI: 19-26 kg/m2, mean±SD: 22.3±1.9) women underwent a battery of experimental procedures, including resting-state functional magnetic imaging to examine task-independent functional brain connectivity at two time points. 13 obese and 33 lean participants returned for the second part of the experiments about 6 months later, which was surgery-dependent for the obese group. Bariatric bypass surgery Surgery achieves substantial weight loss in obese patients, reducing mean body weight from 119 to 87 kg six months after surgery, which equals a reduction of 27% in body weight. Statistical analyses Based on prior task-dependent work on dietary self-control, we applied ROI-to-ROI and seed-to-voxel analysis in our two regions of interest, i.e. ventromedial (vmPFC) and dorsolateral (dlPFC) prefrontal cortex, that are related to self-control success and valuation in task-based fMRI studies [2,3]. Masks for those regions were constructed based on Neurosynth data (neurosynth.org) and transformed using previously established methods to create strict and liberal regional masks [4]. Seed-to-voxel connectivity scores were extracted as mean connectivity values per subject, yielding one connectivity measure for each seed region connected to multiple clusters per subject. All analyses were corrected for age due to its effect on resting-state connectivity [5], by integrating it as a co-variate of no interest. All results were obtained applying multiple comparisons using FDR and were considered significant at a threshold for p-FDR Results ROI-to-ROI connectivity between vmPFC and dlPFC at rest related to self-control success in task based fMRI studies is stronger in obesity compared to lean independent of surgery (two-way ANOVA [F(1,84)=5.8, p=0.02]). Seed-to-voxel connectivity of the vmPFC shows that after bariatric surgery the striatum is reintegrated into reward-related circuits in the obese group compared to the difference over time in the lean group (pFWE Conclusion This is the first longitudinal study investigating functional brain connectivity at rest demonstrating the effect of bariatric surgery six months after the operation in morbidly obese individuals. Our findings suggest bariatric surgery as an effective treatment not only on weight status but also on brain circuits in obese patients. The reintegration of the striatum within the brain’s reward circuit indicates that bariatric surgery could help to counteract brain connectivity patterns that resemble those seen in addictions, namely a hypofunctioning of the reward circuit.