THE GUT–BRAIN AXIS IN MOOD AND ANXIETY DISORDERS: PATHOPHYSIOLOGICAL MECHANISMS, DIAGNOSTIC CHALLENGES, AND THERAPEUTIC IMPLICATIONS

Sandra Olewińska; Aleksandra Lisowska; Oliwia Jerzyńska; Pola Sitek; Dariusz Szołtys; Karolina Zygoń-Komendarczyk; Katarzyna Oberska; Michalina Adamczyk; Tola Kotkiewicz; Yelyzaveta Petrenko

doi:10.31435/ijitss.1(49).2026.4919

Authors

Sandra Olewińska Municipal Hospital in Siemianowice Śląskie, Siemianowice Śląskie, Poland https://orcid.org/0009-0003-7018-8440
Aleksandra Lisowska Municipal Hospital in Siemianowice Śląskie, Siemianowice Śląskie, Poland https://orcid.org/0009-0008-4917-821X
Oliwia Jerzyńska University Clinical Hospital No. 2, Pomeranian Medical University in Szczecin, Szczecin, Poland https://orcid.org/0009-0001-5427-3069
Pola Sitek Municipal Hospital in Siemianowice Śląskie, Siemianowice Śląskie, Poland https://orcid.org/0009-0009-2631-8846
Dariusz Szołtys Municipal Hospital in Siemianowice Śląskie, Siemianowice Śląskie, Poland https://orcid.org/0009-0000-2687-3123
Karolina Zygoń-Komendarczyk Municipal Hospital in Siemianowice Śląskie, Siemianowice Śląskie, Poland https://orcid.org/0009-0005-9916-0972
Katarzyna Oberska Municipal Hospital in Siemianowice Śląskie, Siemianowice Śląskie, Poland https://orcid.org/0009-0004-6701-7584
Michalina Adamczyk Municipal Hospital in Siemianowice Śląskie, Siemianowice Śląskie, Poland https://orcid.org/0009-0002-6325-8298
Tola Kotkiewicz Municipal Hospital in Siemianowice Śląskie, Siemianowice Śląskie, Poland https://orcid.org/0009-0001-6578-3910
Yelyzaveta Petrenko Municipal Hospital Complex in Chorzów, Chorzów, Poland https://orcid.org/0009-0005-9481-472X

DOI:

https://doi.org/10.31435/ijitss.1(49).2026.4919

Keywords:

Gut–Brain Axis, Anxiety Disorders, Gut Microbiota, Mood Disorders, Depression, Irritable Bowel Syndrome

Abstract

Over the past two decades, accumulating evidence has demonstrated bidirectional communication between the gastrointestinal tract and the central nervous system, commonly referred to as the gut–brain axis. This complex network integrates neural, hormonal, immunological, and metabolic pathways and plays a critical role in maintaining both physiological and psychological homeostasis. Increasing attention has been directed toward its involvement in mood and anxiety disorders, which constitute a major global public health challenge.

This narrative review aims to synthesise current human-based research examining gut–brain axis dysfunction in mood and anxiety disorders, with particular emphasis on underlying pathophysiological mechanisms, diagnostic challenges, and emerging therapeutic strategies. A comprehensive literature search was conducted using PubMed, Scopus, and Web of Science, focusing on original clinical, neuroimaging, and translational studies published between 2000 and 2025.

The available evidence indicates that alterations in gut microbiota composition, increased intestinal permeability, immune system activation, and changes in microbial metabolite production are consistently associated with depressive and anxiety-related symptoms. Moreover, the high prevalence of psychiatric comorbidity observed in functional and inflammatory gastrointestinal disorders supports the existence of shared biological pathways. Despite significant advances, the clinical translation of gut–brain research remains limited by the lack of standardised diagnostic tools and validated biomarkers.

This review highlights the therapeutic potential of novel interventions, including psychobiotics, dietary modifications, and microbiota-targeted therapies, while emphasising the need for interdisciplinary collaboration and further human studies to support their integration into routine clinical practice.

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