Probiotic (LGG) for Veterans With PTSD

United States military Veterans from recent conflicts are coping with symptoms related to posttraumatic stress disorder (PTSD). Many Veterans are resistant to conventional health and mental health interventions (e.g., medication, psychotherapy), and often symptoms are not significantly improved by traditional treatments. Alternative treatment methods are needed. An underlying feature of PTSD is exaggerated inflammation, both peripherally and in the central nervous system, which is thought to play an important role in the vulnerability to, aggravation of, and perpetuation of adverse consequences of this condition. Therefore, an innovative intervention strategy would be the use of immunoregulatory/anti-inflammatory probiotics to reduce inflammation. In this study, the investigators will investigate the effects of an 8-week oral administration of an immunoregulatory probiotic, Lactobacillus rhamnosus GG (LGG; ATCC53103), a probiotic shown to have anti-inflammatory and immunoregulatory effects (i.e., decreases in C-reactive protein \[CRP\]). Project aims will be assessed using a longitudinal, double blind, randomized placebo-controlled design. After initial evaluation procedures to confirm PTSD diagnosis, 59 participants will be randomized to probiotic supplementation and 59 will be randomized to placebo supplementation. Primary Aim. Demonstrate the effects of LGG in a cohort of OEF/OIF Veterans with PTSD and Functional Bowel Disorders (FBD), including IBS, on plasma CRP concentrations (mechanistic, primary outcome), and PTSD symptom severity (clinical, exploratory). Additional biological signatures associated with this condition will be considered exploratory, including gut microbial community and intestinal permeability \[IP\]), other biological signatures of inflammation, as well as stress responsivity and decision making. Hypothesis 1.1. Those who receive LGG supplementation will respond with lower plasma levels of CRP as compared to those allocated to placebo. Exploratory Hypothesis 1.2. Those who receive LGG supplementation will respond with decreased PTSD symptoms (PCL-5), as compared to those allocated to placebo. Exploratory Hypothesis 1.3. Those who receive LGG supplementation will respond with increased abundance of LGG and community-level shifts (e.g.,increased alpha diversity) in the gut microbiota (measured using qRT-PCR and DNA sequencing of the 16S rRNA gene, respectively), decreases in IP (decreased fatty acid binding protein 215 and D-amino acid oxidase16), increases in plasma concentrations of anti-inflammatory biomarkers (IL-10, IL-4), decreases in additional plasma biomarkers of inflammation (IL-6, IL-8, IFNγ, IL- 1α, IL-1β, and IL-12p70), reduced stress response (biological and psychological) during and after Cyberball, and improved decision-making (measured by performance on the modified Iowa Gambling Test \[mIGT\]) as compared to those allocated to placebo. Exploratory Hypothesis 1.4. The effect of LGG supplementation on stress response, decision-making, and PTSD symptom severity is mediated by effects of LGG supplementation on the gut microbiota, intestinal permeability, and plasma biomarkers of inflammation.