Abstract

Feeling down? A systematic review of the gut microbiota in anxiety/depression and irritable bowel syndrome

Simpson CA1, Mu A2, Haslam N3, Schwartz OS4, Simmons JG5. J Affect Disord. 2020 Jan 22;266:429-446. doi: 10.1016/j.jad.2020.01.124. [Epub ahead of print]

 
     

Author information

Melbourne School of Psychological Sciences, The University of Melbourne, 12th floor Redmond Barry Building, Parkville, VIC, Australia; Melbourne Neuropsychiatry Centre, The University of Melbourne and Melbourne Health, VIC, Australia. Electronic address: carra.simpson@unimelb.edu.au.

Department of Microbiology and Immunology at the Peter Doherty Institute for Infection and Immunity, The University of Melbourne, VIC, Australia; Doherty Applied Microbial Genomics, Department of Microbiology and Immunology at the Peter Doherty Institute for Infection and Immunity, The University of Melbourne, VIC, Australia; Microbiological Diagnostic Unit Public Health Laboratory, at the Peter Doherty Institute for Infection and Immunity, The University of Melbourne, VIC, Australia.

Melbourne School of Psychological Sciences, The University of Melbourne, 12th floor Redmond Barry Building, Parkville, VIC, Australia.

Orygen, The National Centre of Excellence in Youth Mental Health; Centre for Youth Mental Health, The University of Melbourne, VIC, Australia.

Melbourne School of Psychological Sciences, The University of Melbourne, 12th floor Redmond Barry Building, Parkville, VIC, Australia; Melbourne Neuropsychiatry Centre, The University of Melbourne and Melbourne Health, VIC, Australia.

Abstract

Background Anxiety/depression and irritable bowel syndrome (IBS) are highly prevalent and burdensome conditions, whose co-occurrence is estimated between 44 and 84%. Shared gut microbiota alterations have been identified in these separate disorders relative to controls; however, studies have not adequately considered their comorbidity. This review set out to identify case-control studies comparing the gut microbiota in anxiety/depression, IBS, and both conditions comorbidly relative to each other and to controls, as well as gut microbiota investigations including measures of both IBS and anxiety/depression. Methods Four databases were systematically searched using comprehensive search terms (OVID Medline, Embase, PsycINFO, and PubMed), following PRISMA guidelines. Results Systematic review identified 17 studies (10 human, 7 animal). Most studies investigated the gut microbiota and anxiety/depression symptoms in IBS cohorts. Participants with IBS and high anxiety/depression symptoms had lower alpha diversity compared to controls and IBS-only cohorts. Machine learning and beta diversity distinguished between IBS participants with and without anxiety/depression by their gut microbiota. Comorbid IBS and anxiety/depression also had higher abundance of Proteobacteria, Prevotella/Prevotellaceae, Bacteroides and lower Lachnospiraceae relative to controls. Limitations A large number of gut microbiota estimation methods and statistical techniques were utilized; therefore, meta-analysis was not possible. Conclusions Well-designed case-control and longitudinal studies are required to disentangle whether the gut microbiota is predicted as a continuum of gastrointestinal and anxiety/depression symptom severity, or whether reported dysbiosis is unique to IBS and anxiety/depression comorbidity. These findings may inform the development of targeted treatment through the gut microbiota for individuals with both anxiety/depression and IBS.

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