Gut Microbial Composition Is Associated with Symptom Self-Report in Trauma-Exposed Iraq and Afghanistan Veterans

Sep 30, 2026

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Iraq and Afghanistan War-era Veterans face elevated risks for physical injury and psychiatric illness, especially the polytrauma clinical triad involving mild traumatic brain injury, PTSD, and chronic pain. This study investigates whether gut microbiome composition relates to post-deployment symptom self-report. Male Veterans who completed a comprehensive VA TBI evaluation provided PTSD, pain, fatigue, cognitive, substance use, and sleep measures and fecal samples. Metagenomic sequencing assessed alpha and beta diversity and taxonomic profiles, revealing significant associations with fatigue, post-concussive symptoms, executive function symptoms, and cannabis use, particularly Verrucomicrobiota.

LanguageEnglish

CategoryResearch & Report

FormatPDF

Pages12

Reading Time30 min

AccessFree to download

Abstract

Background

Methods

Results

Conclusions

Neurotrauma Reports Volume 6.1, 2025 DOI: 10.1089/neur.2024.0011 Open camera or QR reader and scan code to access this article and other resources online. REGULAR MANUSCRIPT Open Access Gut Microbial Composition Is Associated with Symptom Self-Report in Trauma-Exposed Iraq and Afghanistan Veterans Y. Irina Li,1,2 Kathleen Pagulayan,3 Holly Rau,3 Rebecca Hendrickson,1,4 and Abigail G. Schindler4–7,* | | | --- | | Abstract | | Iraq and Afghanistan War-era Veterans are at elevated risk for physical injuries and psychiatric illnesses, in particular the polytrauma triad of mild traumatic brain injury (mTBI), post-traumatic stress disorder (PTSD), and chronic pain. The gut microbiome has been implicated in modulation of critical processes beyond digestion, including immune system functioning and stress responsivity, and may be an important factor in understanding physical and mental health outcomes following deployment and trauma exposure. However, minimal research to date has sought to characterize gut microbiome composition in this population. Male Veterans of the conﬂicts in Iraq and Afghanistan who previously completed a Veterans Affairs’ comprehensive TBI evaluation were enrolled in the current study. Participants completed self-report measures of PTSD symptom severity, pain intensity and interference, fatigue, cognitive symptoms, substance use, and sleep quality. They also submitted fecal samples, and metagenomic sequencing was used to calculate alpha and beta diversity and taxonomic microbial composition. Associations between microbiome data and clinical variables were then examined. Alpha and beta diversity measures were not signiﬁcantly correlated with clinical outcomes. Fatigue, post-concussive symptoms, executive function symptoms, and cannabis use were associated with differences in gut microbial composition, speciﬁcally Verrucomicrobiota. Together, results suggest that altered gut microbiome composition is associated with psychiatric and cognitive symptoms in Veterans and highlight a potential new therapeutic target of interest. Future research is needed to examine whether probiotic treatment is effective for reducing symptoms common in this clinical population.
Keywords: gut microbiome; military deployment; polytrauma clinical triad; trauma; Veterans | 3Department of Rehabilitation Medicine, University of Washington, Seattle, Washington, USA. 2Department of Anesthesiology, VA Puget Sound Health Care System, Seattle, Washington, USA. 1Northwest Mental Illness Research, Education and Clinical Center, Veterans Affairs (VA) Puget Sound Health Care System, Seattle, Washington, USA. 4Department of Psychiatry and Behavioral Sciences, University of Washington, Seattle, Washington, USA. 5Graduate Program in Neuroscience, University of Washington, Seattle, Washington, USA. 6VA Northwest Geriatric Research Education and Clinical Center, VA Puget Sound Health Care System, Seattle, Washington, USA. 7Department of Medicine, University of Washington, Seattle, Washington, USA. *Address correspondence to: Abigail G. Schindler, PhD, Department of Psychiatry and Behavioral Sciences, University of Washington, VA Puget Sound Health Care System, S182, 1660 South Columbian Way, Seattle, WA 98108, USA; E-mail: [aschind@u.washington.edu](aschind@u.washington.edu) ª The Author(s) 2025. Published by Mary Ann Liebert, Inc. This Open Access article is distributed under the terms of the Creative Commons License [CC-BY] ([http://creativecommons.org/licenses/by/4.0](http://creativecommons.org/licenses/by/4.0)), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. 1 Li et al.; Neurotrauma Reports 2025, 6.1 2 [http://online.liebertpub.com/doi/10.1089/neur.2024.001](http://online.liebertpub.com/doi/10.1089/neur.2024.001)1 Background The negative impact on physical and mental health following deployment to war zones among U.S. military per

FAQs

What population and study design were used to assess symptom self-report and gut microbiome composition?

Male Iraq and Afghanistan War-era Veterans who had previously completed a comprehensive VA TBI evaluation were enrolled. Participants provided symptom self-report measures and fecal samples for metagenomic sequencing.

Which symptom domains showed associations with differences in gut microbial composition?

Fatigue, post-concussive symptoms, executive function symptoms, and cannabis use were associated with gut microbial composition differences, particularly involving Verrucomicrobiota.

Were gut microbiome diversity measures linked to clinical outcomes in this study?

Alpha and beta diversity measures were not significantly correlated with clinical outcomes.

Sep 30, 2026

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