Inadequate immunoregulation and elevated inflammation may be risk factors for posttraumatic stress disorder (PTSD), and microbial inputs are important determinants of immunoregulation; however, the association between the gut microbiota and PTSD is unknown. This study investigated the gut microbiome in a South African sample of PTSD-affected individuals and trauma-exposed (TE) controls to identify potential differences in microbial diversity or microbial community structure.
The Clinician-Administered PTSD Scale for DSM-5 was used to diagnose PTSD according to Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition criteria. Microbial DNA was extracted from stool samples obtained from 18 individuals with PTSD and 12 TE control participants. Bacterial 16S ribosomal RNA gene V3/V4 amplicons were generated and sequenced. Microbial community structure, α-diversity, and β-diversity were analyzed; random forest analysis was used to identify associations between bacterial taxa and PTSD.
There were no differences between PTSD and TE control groups in α- or β-diversity measures (e.g., α-diversity: Shannon index, t = 0.386, p = .70; β-diversity, on the basis of analysis of similarities: Bray-Curtis test statistic = –0.033, p = .70); however, random forest analysis highlighted three phyla as important to distinguish PTSD status: Actinobacteria, Lentisphaerae, and Verrucomicrobia. Decreased total abundance of these taxa was associated with higher Clinician-Administered PTSD Scale scores (r = –0.387, p = .035).
In this exploratory study, measures of overall microbial diversity were similar among individuals with PTSD and TE controls; however, decreased total abundance of Actinobacteria, Lentisphaerae, and Verrucomicrobia was associated with PTSD status.
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From the Department of Psychiatry (Hemmings, Malan-Müller, van den Heuvel, Seedat), Faculty of Medicine and Health Sciences, Stellenbosch University, Tygerberg, South Africa; Departments of Molecular, Cellular and Developmental Biology (Demmitt, Krauter), Chemistry and Biochemistry (Smith), and Integrative Physiology (Bohr, Stamper, Siebler, McQueen, Lowry), Institute for Behavioral Genetics (Demmitt, Bohr, McQueen, Krauter), and Center for Neuroscience (Lowry), University of Colorado Boulder, Boulder; Departments of Epidemiology (Stanislawski), Psychiatry and Neurology (Brenner), and Physical Medicine and Rehabilitation (Brenner, Lowry), and Center for Neuroscience (Lowry), University of Colorado Anschutz Medical Campus, Aurora; US Department of Veterans Affairs (Stanislawski), Denver, CO; Departments of Pediatrics (Hyde, Marotz, Knight) and Computer Science & Engineering (Morton, Knight), and Center for Microbiome Innovation (Knight), University of California San Diego, La Jolla, CA; NXT-Dx (Braspenning); Department of Mathematical Modelling (Van Criekinge), Statistics and Bio-informatics, Ghent University, Gent, Belgium; Department of Civil and Environmental Engineering (Hoisington), United States Air Force Academy, Colorado Springs; Military and Veteran Microbiome Consortium for Research and Education (MVM-CoRE) (Hoisington, Brenner, Postolache, Lowry); VA Rocky Mountain Mental Illness Research, Education, and Clinical Center (MIRECC) (Brenner, Postolache, Lowry), Denver, CO; and Department of Psychiatry (Postolache), School of Medicine, University of Maryland, Baltimore, MD.
Address correspondence and reprint requests to Christopher A. Lowry, PhD, Department of Integrative Physiology and Center for Neuroscience, University of Colorado Boulder, Boulder, CO 80309-0354. E-mail: firstname.lastname@example.org
S.M.J.H. and S.M.-M. equally contributed to this work.
Received for publication May 12, 2016; revision received April 26, 2017.