Effects of exercise training on functional connectivity and cerebral gray matter in patients undergoing bariatric surgery: a randomized controlled trial

Author(s)

Carlos Alberto Abujabra Merege Filho

• Document type: Doctoral Thesis
• Press: São Paulo.
• Institution: Universidade de São Paulo (USP). Faculdade de Medicina (FM/SBD)
• Defense date: 2023-02-07

Examining board members

Bruno Gualano; Fabiana Braga Benatti; Andrea Camaz Deslandes; Maria da Graça Morais Martin

• Advisor: Bruno Gualano

Abstract

Obesity is a multifactorial disease that may negatively affect central nervous system (CNS). Bariatric surgery is an effective treatment for obesity, and the positive effects on obesity-related conditions may be enhanced by exercise. Although exercise training is recognized to positively influence CNS in patients with obesity, there are no studies investigating the synergistic effects of these two interventions on brain functional organization assessed by connectivity analysis. Furthermore, is not known if the changes after bariatric surgery on cerebral gray matter, the main structural component of CNS, is enhanced without lifestyle changes of these patients, such as physical exercise training. Therefore, the aims of this study were investigating the effects of exercise training on functional connectivity of brain networks that are involved in the food intake control and obesity pathophysiology (study 1), as well as the effects on the volume of gray matter assessed by morphometry analysis (study 2). Thirty patients eligible for bariatric surgery were randomized to participate in a 6-month exercise training program (RYGB+ET: n = 15, age = 41.9 ± 7.2 years) or standard care (RYGB: n = 15, age = 41.0 ± 7.3 years). At the baseline 3 and 9 months after bariatric surgery -, the brain connectivity was assessed by resting-state functional magnetic resonance imaging using T2-weighted Echo planar imaging (EPI) pulse sequence, and brain morphometry was obtained by the high resolution T1-weighted volumetric acquisition performed with the three-dimensional Turbo Field Echo (3DT1-TFE) technique. Exercise superimposed on bariatric surgery resulted in increased connectivity between the hypothalamus and sensorial regions (seed-to-voxel analyses of hypothalamic connectivity), and decreased default mode network (DMN) and salience network (SAL) connectivity (ROI-to-ROI analyses of brain networks connectivity). Still, increases in basal ganglia (BG) network connectivity were only observed in the exercised group (within-group analyses). Contrary to our hypothesis, exercise training induced synergistic effects of Roux-en-Y Gastric Bypass upon gray matter alterations in obesity (i.e., subcortical volume) were not found. In conclusion, exercise training is an important component in the management of post-bariatric patients and may improve the hypothalamic connectivity and brain functional networks that are involved in controlling food intake and obesity pathophysiology. However, findings of morphometry data show that undertaking an exercise training program after bariatric surgery did not superimpose brain structural plastic in patients undergoing bariatric surgery. Randomized clinical trial with long-term follow-up are needed to answer this question (AU)

• FAPESP's process: 17/16104-0 - Effects of physical exercise training on brain structure and metabolism in patients undergoing bariatric surgery: randomized, controlled, clinical trial
• Grantee: Carlos Alberto Abujabra Merege Filho
• Support Opportunities: Scholarships in Brazil - Doctorate