The Gut–Brain Axis in Gastrointestinal Disorders: A Comprehensive Review

Abstract

The gut–brain axis (GBA) is a bidirectional communication network integrating neural, endocrine, immune and microbial signals between the gastrointestinal (GI) tract and the central nervous system (CNS). Once regarded chiefly as a regulator of motility and secretion, the GBA is now recognised as a central pathophysiological driver across the spectrum of GI disease — from functional conditions such as irritable bowel syndrome (IBS) and functional dyspepsia (FD) to organic disorders including inflammatory bowel disease (IBD), gastro-oesophageal reflux disease (GERD), gastroparesis, chronic constipation, coeliac disease, non-alcoholic fatty liver disease (NAFLD) and GI cancers. The Rome V update (2026) formally consolidates functional GI disorders as disorders of gut–brain interaction (DGBI), acknowledging dysregulated gut–brain signalling in their pathogenesis. This review synthesises current evidence on GBA mechanisms across major GI disorders, highlighting shared pathophysiological pathways — dysbiosis, barrier failure, visceral hypersensitivity, neuroimmune activation and altered serotonergic and hypothalamic–pituitary–adrenal (HPA) signalling — together with disease-specific perturbations and evolving axis-directed therapeutics [1].

Keywords: gut–brain axis; microbiota; disorders of gut–brain interaction; irritable bowel syndrome; inflammatory bowel disease; GERD; functional dyspepsia; gastroparesis; constipation; coeliac disease; NAFLD; colorectal cancer; visceral hypersensitivity; vagus nerve; dysbiosis; probiotics; faecal microbiota transplantation

 Introduction

The gut–brain relationship has been recognised since William Beaumont documented emotional influences on gastric secretion, but only in the past two decades have microbiome science, neuroimaging and immunology revealed the full complexity of this network. The GBA links the enteric nervous system (ENS), autonomic nervous system, HPA axis, mucosal immune system and gut microbiome into an integrated signalling architecture governing both GI physiology and CNS function [2,3,4].