Gut Microbiota and Mycobiota Evolution is linked to Short-Term and Working Memory improvement after-Bariatric Surgery of Obese Patients

Obesity is a risk factor for cognitive disorders. However, few human data are available concerning the underlying mechanisms and possible reversibility of cognitive decline after weight loss. In addition to insulin resistance that is known to be involved in type 2 diabetes associated cognitive decline, another potential mechanism through which obesity could affect cognitive function is alterations in gut microbiota. Indeed, hypercaloric diets trigger robust alterations in the gut microbiota and evidence from animals and humans implies that gut microbiota affects brain structure and cognitive function. Preliminary data that we have generated in a small cohort of obese patients using a new task highly sensitive in detecting hippocampal dysfunction show that: i) obese subjects show memory decline associated with hippocampal dysfuntion, and ii) young and middle-aged obese subjects have same memory decline described in elderly normal weight people. The present project therefore aims at 1) fully characterizing memory decline induced by obesity; 2) determining its potential reversibility after weight loss induced by bariatric surgery according to obesity anteriority; 3) examining the association between alteration of gut microbiota and cognitive function before and after weight loss. Young and middle-age obese patients before and after bariatric surgery, young and middleage normal weight patients and normal weight aged patients will be phenotyped on cognition, physical activity, eating behavior, metabolic and anthropometric parameters. Brain MRI will be performed before and after bariatric surgery to observe morphological changes in hippocampus. Gut microbiota profile susceptible to link obesity and memory dysfunctions will be assessed together with metabolic parameters including insulin resistance. We expect that such multidisciplinary approach will allow better characterization of memory decline in obesity, revealing the potential beneficial effect of bariatric surgery and the link with changes in gut microbiota profile.