Nutrition and the gastrointestinal tract: Edited by Maria Isabel Toulson Davisson Correia and Miquel A. GassullThe new link between gut–brain axis and neuropsychiatric disordersFetissov, Sergueï O.; Déchelotte, PierreAuthor Information Digestive System and Nutrition Laboratory (ADEN EA4311), Institute for Medical Research and Innovation, IFRMP23, Rouen University Hospital, Rouen University, Rouen, France Correspondence to Dr Sergueï O. Fetissov, MD, PhD, ADEN Laboratory, Faculté de Médecine-Pharmacie, 22 Boulevard Gambetta, Rouen 76183, Cedex 1, FranceTel: +33 235 148 455; fax: +33 235 148 226; e-mail: Serguei.Fetissov@univ-rouen.fr Current Opinion in Clinical Nutrition and Metabolic Care: September 2011 - Volume 14 - Issue 5 - p 477-482 doi: 10.1097/MCO.0b013e32834936e7 Buy Metrics Abstract Purpose of review Although the cause of most neuropsychiatric disorders remains uncertain, new data offer alternative explanations warranting further validations. This review summarizes some recent findings that may localize the origin of eating disorders as well as some other neuropsychiatric disorders outside the brain and discuss their cause as a possible dysfunction of the gut–brain axis involving the humoral immune system. Recent findings The gut microbiota has been identified as the main source of highest biological variability confined in an individual and also provides constant antigenic stimulation shaping up the physiological immune response. Furthermore, molecular mimicry has been shown among microbial proteins including gut microbiota and several key neuropeptides involved in the regulation of motivated behavior and emotion. Immunoglobulins reactive with these neuropeptides have been identified in humans, and their levels or affinities were associated with neuropsychiatric conditions including anxiety, depression, eating and sleep disorders. Summary Cross-reacting immunoglobulins may bind both microbial sequences and neuropeptides, thereby constituting a particular way of signaling between the gut and the brain. Alteration of this link may contribute to several neuropsychiatric disorders, emphasizing the key role of nutrition among other factors influencing gut content and intestinal permeability. © 2011 Lippincott Williams & Wilkins, Inc.