Gut Microbiota and Mycobiota Evolution Is Linked to Memory Improvement after Bariatric Surgery in Obese Patients: A Pilot Study.

Raphaël Enaud,Samantha Clark,Emilie Chancerel,Erwan Guichoux,Sophie Cambos,Blandine Gatta-Cherifi,Aline Marighetto,Laurence Delhaes,Nicole Etchamendy,Daniela Cota,Kamel Mohammedi,Esther Viaud

doi:10.3390/nu13114061

Abstract

Patients with obesity are known to exhibit gut microbiota dysbiosis and memory deficits. Bariatric surgery (BS) is currently the most efficient anti-obesity treatment and may improve both gut dysbiosis and cognition. However, no study has investigated association between changes of gut microbiota and cognitive function after BS. We prospectively evaluated 13 obese patients on anthropometric data, memory functions, and gut microbiota-mycobiota before and six months after BS. The Rey Auditory Verbal Learning Test (AVLT) and the symbol span (SS) of the Weschler Memory Scale were used to assess verbal and working memory, respectively. Fecal microbiota and mycobiota were longitudinally analyzed by 16S and ITS2 rRNA sequencing respectively. AVLT and SS scores were significantly improved after BS (AVLT scores: 9.7 ± 1.7 vs. 11.2 ± 1.9, p = 0.02, and SS scores: 9.7 ± 23.0 vs. 11.6 ± 2.9, p = 0.05). An increase in bacterial alpha-diversity, and Ruminococcaceae, Prevotella, Agaricus, Rhodotorula, Dipodascus, Malassezia, and Mucor were significantly associated with AVLT score improvement after BS, while an increase in Prevotella and a decrease in Clostridium, Akkermansia, Dipodascus and Candida were linked to SS scores improvement. We identified several changes in the microbial communities that differ according to the improvement of either the verbal or working memories, suggesting a complex gut-brain-axis that evolves after BS.

Highlights

IntroductionCardiometabolic disease and cancer, obesity is a recognized risk factor for cognitive disorders including memory decline [1,2,3]
Besides causing diabetes, cardiometabolic disease and cancer, obesity is a recognized risk factor for cognitive disorders including memory decline [1,2,3]
We prospectively evaluated patients with obesity aged between 18 and 65 years, followed in the Nutrition Department of the Bordeaux University Hospital, requiring a bariatric surgery planned according to the guidelines of the French Health Authority: BMI > 40 kg/m2 or > 35 kg/m2 in the presence of complications susceptible to be improved by bariatric surgery

Summary

Introduction

Cardiometabolic disease and cancer, obesity is a recognized risk factor for cognitive disorders including memory decline [1,2,3]. Little data is available in humans concerning the underlying mechanisms of obesity-related memory impairment and of its potential reversibility with weight loss. One potential mechanism through which obesity could affect cognitive function is modifications in gut microbiota. Gut microbiota dysbiosis is well documented in obesity [4]. Hypercaloric diets trigger robust gut microbiota disturbances (or dysbiosis) and evidence from animals and humans implies that gut microbiota affects brain structure and cognitive function [5,6]. A specific microbiota profile that involves aromatic amino acid and one-carbon metabolism has been significantly associated with memory and modulated by obesity [1]

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Conclusion