The influence of the brain–gut axis in inflammatory bowel disease and possible implications for treatment

Brain–gut interactions affect psychological wellbeing and symptom reporting in functional gastrointestinal disorders; the presence of anxiety or depression is associated with the development of new-onset gastrointestinal symptoms, and the presence of gastrointestinal symptoms is associated with the development of psychological disorders de novo. In inflammatory bowel diseases (IBD), the reporting of irritable bowel syndrome (IBS)-type symptoms by patients with quiescent disease is common, and is associated with psychological disorders, impaired quality of life, and increased health-care use. In IBD, data from observational studies suggest that psychological disorders might be associated with relapse of disease activity, and that inflammatory activity is associated with the development of new psychological disorders, as has been described for functional gastrointestinal disorders such as IBS and functional dyspepsia. The brain–gut axis provides the physiological link between the CNS and gastrointestinal tract that might facilitate these relationships. In IBS, treatments targeting disordered brain–gut axis activity, including psychological therapies and antidepressants, might lead to improved symptoms and quality of life. However, in IBD, the benefit of these treatments is less certain because of a scarcity of interventional studies. Despite the scarcity of trials, observational data suggest that the effect of disordered brain–gut axis activity in IBD is substantial, and scope remains for further well designed trials of psychological therapies and antidepressants, particularly in the subset of patients who have coexistent psychological disorders, or in those who report IBS-type symptoms. Integrating these treatments into a biopsychosocial model of care has the potential to improve both psychological wellbeing and quality of life in some patients with IBD, reducing health-care use and altering the natural history of disease.