Brain-Gut Interactions in Inflammatory Bowel Diseases

Psycho-neuro-endocrine-immune modulation through the brain-gut axis likely has a key role in the pathogenesis of inflammatory bowel diseases (IBD). The brain-gut axis involves interactions between the neural components including; a) the autonomic nervous system, b) the central nervous system c) the stress system (hypothalamic-pituitary adrenal axis, HPA) and d) the (i.e. gastro-intestinal) corticotropin-releasing factor system and e) the intestinal response (including the intestinal barrier, the luminal microbiota and the intestinal immune response). Animal models suggest that the cholinergic anti-inflammatory pathway through an anti-TNF effect of the efferent vagus nerve could be a therapeutic target in IBD either through a pharmacological, nutritional or neurostimulating approach. In addition, the psychophysiological vulnerability of IBD patients, secondary to the potential presence of any of mood disorders, distress, increased perceived stress or maladaptive coping strategies underscores the psychological needs of IBD patients. Clinicians need to address these issues with patients since there is emerging evidence that stress or other negative psychological attributes may impact on disease course. Future research may include exploration of markers of brain-gut interactions, including serum/salivary cortisol (as a marker of the HPA axis), heart rate variability (as a marker of the sympatho-vagal balance) or brain imaging studies. The widespread use and potential impact of complementary and alternative medicine, and positive response to placebo (in clinical trials) is further evidence that exploring other psychointerventions may be important therapeutic adjuncts to the conventional therapeutic approach in IBD.