Brain and Gut Interactions in Irritable Bowel Syndrome: New Paradigms and New Understandings

Abstract

Irritable bowel syndrome (IBS) is characterized by abdominal pain and altered bowel habits. Visceral hypersensitivity is believed to be a key underlying mechanism that causes pain. There is evidence that interactions within the brain and gut axis (BGA) that involves both, the afferent-ascending and the efferent-descending pathways as well as the somatosensory cortex, insula, amygdala, anterior cingulate cortex and hippocampus are deranged in IBS showing both the activation and inactivation. Clinical manifestations of IBS such as pain, altered gut motility and psychological dysfunction may each be explained, in part through the changes in the BGA but there is conflicting information and its precise role is not fully understood. A better understanding of the BGA may shed more knowledge regarding the pathophysiology of IBS that in turn may lead to the discovery of novel therapies for this common disorder.

Lorcaserin Administration Decreases Activation of Brain Centers in Response to Food Cues and These Emotion- and Salience-Related Changes Correlate With Weight Loss Effects: A 4-Week-Long Randomized, Placebo-Controlled, Double-Blind Clinical Trial

“…Among their involvement in other CNS systems, the insula and amygdala are both involved in salience and emotional processing (29–33). Although the insula is also involved in proprioception and taste (34), its activation in this study could be related to salience or to changes in gut motility and cue priming to involve the enteric nervous system resulting from the posterior location of the activation (35). This relative increase between 1 and 4 weeks may represent attenuation at 4 weeks, where brain activations begin to return to control/baseline levels.…”

The Increased Level of Depression and Anxiety in Irritable Bowel Syndrome Patients Compared with Healthy Controls: Systematic Review and Meta-analysis

“…4 Psychosocial factors impair mucosal secretory and barrier function through alteration of the efferent autonomic nervous system and the stress hormone system (hypothalamo-pituitary-adrenal axis), resulting in the translocation of bacterial cell products. 1,4,9 Animal studies have demonstrated the influence of stress on colonic permeability, and mucosal and systemic inflammation's mediation by the autonomic nervous system and the hypothalamo-pituitary-adrenal axis. 4 Several recently published studies have mapped IBS's relationship with psychological disorders [10][11][12][13][14][15][16] and compared depression and anxiety levels in IBS-subtypes.…”

Irritable Bowel Syndrome

“…Such investigations illustrate that patients with IBS exhibit differences in brain structure, connectivity, and functional responsiveness in comparison to healthy controls (Weaver, Sherwin, Walitt, Melkus & Henderson, 2016). It is proposed that the clinical presentation of IBS patients with pain, psychological comorbidities, and altered gut motility may be explained through changes in the BGA, although mechanisms are not fully understood (Coss-Adame & Rao, 2014). Despite great progress in understanding the pathophysiology of IBS, such discoveries have not been fully translated to the clinical arena; patient diagnosis remains one primarily of exclusion, and treatment interventions remain symptom driven.…”