Gut-Brain Axis: Implications for Irritable Bowel Syndrome and Other Functional Disorders

Abstract

Introduction: Irritable Bowel Syndrome (IBS) involves the interaction between psychosocial and physiological factors, and the brain-gut axis. Anxiety, depression, and stress intensify symptoms through activation of the hypothalamic-pituitary-adrenal axis and dysfunction in pain-related brain areas. The gut microbiota also influences inflammatory and cognitive processes. Thus, therapies such as cognitive-behavioral therapy and hypnotherapy have been shown to be effective in reducing pain and symptoms. Objective: To investigate the influence of the brain-gut axis on IBS, considering psychosocial factors, stress, and the gut microbiota, and to evaluate the effectiveness of integrated psychotherapeutic interventions in modulating symptoms. Methodology: A literature review was conducted between May and September 2025, using the Virtual Health Library (VHL) and PubMed databases. Articles published in Portuguese, English, Spanish, and French related to the topic from 2017 to 2025 were included, prioritizing reviews, meta-analyses, and randomized clinical trials. Results: Studies indicate that IBS is strongly associated with gut-brain axis dysfunctions, involving alterations in intestinal motility, visceral hypersensitivity, low-grade inflammation, and neurochemical imbalances, such as reduced GABAergic activity. Patients with IBS have a higher prevalence of psychological symptoms and an increased risk of developing neurological diseases. Interventions targeting the gut-brain axis and physical exercise have shown efficacy in reducing abdominal pain and improving quality of life, although studies still have sample and standardization limitations. Conclusion: Irritable Bowel Syndrome is a multifactorial disorder of the gut-brain axis, modulated by neuroendocrine, immunological, and emotional factors. Chronic stress, dysbiosis, and inflammation intensify gastrointestinal and psychiatric symptoms and may precede manifestations of neurological diseases. Integrative strategies, including pharmacological and behavioral therapies, and physical activity, are essential for personalized and effective clinical management.