Impacts of Bariatric Surgery on the Microbiome and Brain Function

Emerging evidence suggests that dietary and metabolic interventions could potentially target prevention and supportive therapies as well as treatments that may slow the clinical deterioration of neurodegenerative disorders. Though certain dietary patterns can impair specific cognitive domains, e.g., declines in reasoning and global cognition, there is still no consensus on the optimal diet to maintain brain health. Studies have also shown an association between the gut microbiome and neurocognition, as the microbiota can affect neuronal function through neurotransmitters and neuroactive microbial metabolites. Furthermore, studies indicate that diet may strongly influence the gut microbiota. However, the mechanisms for these complex relationships are still poorly understood. Bariatric procedures \[i.e., weight loss surgeries\] create a unique environment, in which a fast change in gut microbiota composition and dietary patterns occurs through surgery-induced intestinal and metabolic modifications, leading to changes in gut-brain communication. Interestingly, improvements in neurocognitive domains including memory and executive function have been reported post-bariatric surgery. However, there is large variability in these outcomes, indicating that the benefits are not universal. The goal of the current study is to explore the associations between dietary patterns and gut microbiota with cognition and brain structure, using bariatric surgery as an efficient naturalistic experimental design. This project will also explore potential mediators of diet-microbiome alterations as they relate to improvements in brain function and structure. A total of 120 adult patients (\> 30y yrs.) scheduled to undergo a first bariatric surgery along with 60 age-, sex-, and BMI-matched waitlist control group will be recruited from the bariatric surgery clinic at the CIUSSS du Nord-de-l'Île-de-Montréal. These individuals will undergo assessments 3 months before surgery, as well as 6- and 12