About ten years ago, psychologist Lisa Brenner and her team interviewed 103 soldiers returning from Iraq and Afghanistan at Fort Carson, Colorado Springs, aiming to understand the physical and emotional toll of deployment.
The veterans’ responses revealed a complex mix of symptoms, often blurring the lines between mild traumatic brain injury (mTBI) and post-traumatic stress disorder (PTSD).
“Many veterans came back exhibiting symptoms consistent with both brain injury and PTSD,” said Brenner, a researcher at the University of Colorado School of Medicine. Although these conditions frequently co-occurred, treatments often addressed them separately.
During interviews, one veteran’s remark about “gut pain” following a blast injury piqued Brenner’s interest and led to a pioneering research path exploring the connection between brain injuries, PTSD, and gut health.
Her global investigation connected battlefield trauma to the microbiome—the community of microbes residing in the gut.
This discovery underpins an ongoing NIH-funded, five-year randomized controlled trial testing whether a probiotic containing Lactobacillus rhamnosus GG (LGG) can alleviate PTSD symptoms by restoring gut microbial balance, reducing inflammation, and regulating immune responses in veterans.
Co-led with University of Colorado Boulder professor Christopher Lowry, the study builds on their shared focus on the relationship between inflammation, the brain, and the microbiome.
Lowry’s prior research uncovered that certain bacteria, like Mycobacterium vaccae from East African mud, may elevate serotonin levels and reduce anxiety and PTSD-like symptoms in animal models.
Their earlier pilot trials with probiotics such as Lactobacillus reuteri showed promising results, including reductions in inflammation markers like C-reactive protein (CRP). The current Phase 2 trial aims to deepen understanding of how gut health influences PTSD, potentially offering a novel, accessible supplement to complement existing therapies.
Brenner emphasizes that probiotics are not a replacement for evidence-based psychotherapy or prescribed medications but could serve as an additional tool for veterans, especially given the limited medication options and barriers to accessing therapy.
Lowry concurs, describing probiotics as a promising adjunct that may help stabilize patients and prepare them for further treatment steps. Both researchers highlight that their work is rooted in foundational science and the vital participation of veterans seeking new avenues for healing.
“The trial wouldn’t be possible without the dedication of veterans eager for alternative treatments,” Brenner said. “Their commitment drives this important research forward.”
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