MOOD AND ANXIETY DISORDERS: Edited by Nikolaj Travica and Wolfgang MarxAdvances in the gut microbiome and mood disordersMörkl, Sabrinaa; Butler, Mary I.b; Lackner, Sonjac Author Information aMedical University of Graz, Department of Psychiatry and Psychotherapeutic Medicine, Graz, Austria bDepartment of Psychiatry, APC Microbiome Ireland, University College Cork, Cork, Ireland cMedical University of Graz, Division of Immunology and Pathophysiology, Otto Loewi Research Center, Graz, Austria Correspondence to Sabrina Mörkl, Auenbruggerplatz 31/1, Graz 8036, Austria. Tel: +4331638581743; e-mail: [email protected] Current Opinion in Psychiatry 36(1):p 1-7, January 2023. | DOI: 10.1097/YCO.0000000000000829 Buy Metrics Abstract Purpose of review The gut microbiome is in constant bidirectional communication with the brain through the microbiota-gut-brain-axis. Mood disorders are among the most common psychiatric disorders and include major depressive disorder and bipolar disorder. The gut microbiome is altered in individuals with mood disorders and has a role in its inflammatory pathophysiology. In this article, we performed a narrative review of clinical studies, randomized controlled trials and meta-analyses addressing advances in gut microbiome research in mood disorders and included articles that were published between 2021 and 2022. Recent findings Studies highlight transdiagnostic alterations of microbiota in mood disorders, with reductions of butyrate-producing bacteria. Participants with major depressive disorder showed altered beta-diversity, while participants with bipolar disorder showed reduced alpha-diversity. Both disorders exhibit alterations in the metabolome. Early pilot studies addressed the possibility of using the gut microbiome for the prediction of treatment response and the blood microbiome for the diagnosis of psychiatric disorders. Findings from clinical trials support the use of probiotics as an add-on therapy for major depressive disorder. The second published case report in the literature reported a favourable outcome of a patient with bipolar disorder after faecal microbiota transplantation. Summary Gut microbiome modulations allow new treatment strategies including the use of psychobiotics for the treatment and prevention of mood disorders. Well designed clinical trials aiming for personalized medicine are needed to investigate the efficacy and safety of psychobiotic interventions. Copyright © 2022 Wolters Kluwer Health, Inc. All rights reserved.