Association between gut microbiome composition and symptom self-report in trauma exposed OEF/OIF/OND Veterans

ObjectiveIraq and Afghanistan war-era (OEF/OIF/OND) Veterans are at elevated risk for physical injuries and psychiatric illnesses, in particular comorbid mild traumatic brain injury (mTBI), posttraumatic stress disorder (PTSD), and chronic pain. The gut microbiome has been implicated in modulation of critical processes such as digestion, immune system functioning, and stress responsivity, and may be an important factor in understanding physical and mental health outcomes following deployment and trauma exposure, yet minimal research to date has sought to characterize gut microbiome composition in this population. Methods26 male OEF/OIF/OND Veterans aged 18 to 65 who previously completed a VA Comprehensive TBI Evaluation were enrolled in this study. Participants completed self-report measures of PTSD symptom severity, pain intensity and interference, fatigue, cognitive symptoms, substance use, and sleep quality. Participants 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 was then examined. ResultsAlpha 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. ConclusionThis exploratory study demonstrated that altered gut microbiome composition is associated with psychiatric and cognitive symptoms in OEF/OIF/OND Veterans and highlights 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.