Written By: Annie Duong
The bacteria in your gut, or more specifically, the gastrointestinal tract, initially sounds somewhat repulsive but is becoming well known for its overall health benefits. Gut bacteria has been shown to correlate with improved immune system health, reduced inflammation, and reduced risk of diseases such as inflammatory bowel disease (IBD) . Gut bacteria influences both physical health and mental health. Researchers from Stellenbosch University in South Africa and the University of Colorado Boulder have discovered that gut bacteria play a role in regulating hormones involved with stress-related disorders such as post traumatic stress disorder (PTSD) . PTSD is characterized by conditions that impair social functioning including avoidance and negative changes in mood and reactivity . PTSD can be brought on by a wide variety of factors such as experiences of domestic violence, assault, or serious accidents. Stress has been found to alter the makeup of gut bacteria and its communication with the central nervous activity. Lower levels of certain gut bacteria have been found in people diagnosed with PTSD more than those without the disorder. In addition, these people were found to have dysregulated pituitary glands and altered regulatory T cells which play important roles in regulating against autoimmune and inflammatory disease .
The study from Stellenbosch University recruited research participants from general and psychiatric hospitals and community clinics from Cape Town who met the required PTSD diagnosis under the Diagnostic and Statistical Manual of Mental Disorders 5 (DSM-5) scoring criteria to eliminate any confounding variables . The participants were asked to complete a Childhood Trauma Questionnaire (CTQ) to help identify factors that could lead to PTSD in order to determine possible sources of alteration to gut bacteria. The actual bacteria were analyzed after extracting them as samples from stool in a stabilizing solution to maintain its structure. The researchers found that there were a decrease in the amount of actinobacteria, lentisphaerae, and verrucomicrobia in the PTSD participants. The data is consistent with another study conducted by researchers from the University of Helsinki that involved maternal prenatal stress where mothers with high stress levels had lower levels of the bacteria which led to the development of PTSD symptoms .
An explanation for these results include the use of medications for PTSD used by 30% of the participants which may have altered their autonomic nervous systems and disrupted the bacteria’s environment. Furthermore, each individual may have differences in their immune response systems and vulnerabilities to certain PTSD symptoms. Some immune responses such as decreased immunoregulation may be lead to a lower concentration of T cells, overstimulation of the defense symptoms, and exaggerated PTSD symptoms after exposure to a trauma stimulus . Primarily negative associations between PTSD and bacteria amount have been established. Causal relationships could not be determined because the study conducted had a limited sample size. Also, some of the participants expressed borderline PTSD symptoms while others had symptoms associated with other mental disorders. It is important to conduct a longitudinal study to understand the effects of varying microbacteria amounts and to determine a causal relationship for the onset of PTSD symptoms.
The research involving gut bacteria have important applications in clinical and psychiatric settings. Discovering the exact effects of bacterial concentration can help in administering more effective treatments to those affected with PTSD with simple dietary changes in order to change the bacterial environment within our very own bodies .
 Zhang, Y.J., Li, S., Gan, R.Y., Zhou, T., Xu, D.P., and Li, H.B. 2015. Impacts of Gut Bacteria on Human Health and Diseases. Int J Mol Sci. 16(4): 7493 - 7519.
 Sian M.J. Hemmings, Stefanie Malan-Müller, Leigh L. van den Heuvel, Brittany A. Demmitt, Maggie A. Stanislawski, David G. Smith, Adam D. Bohr, Christopher E. Stamper, Embriette R. Hyde, James T. Morton, Clarisse A. Marotz, Philip H. Siebler, Maarten Braspenning, Wim Van Criekinge, Andrew J. Hoisington, Lisa A. Brenner, Teodor T. Postolache, Matthew B. McQueen, Kenneth S. Krauter, Rob Knight, Soraya Seedat, Christopher A. Lowry. The Microbiome in Posttraumatic Stress Disorder and Trauma-Exposed Controls: An Exploratory Study. Psychosomatic Medicine, 2017; 79 (8): 936.
 Zijlmans M.A., Korpela K., Riksen-Walraven J.M/, de Vos W.M., de Weerth C. Maternal prenatal stress is associated with the infant intestinal microbiota. Psychoneuroendocrinology. 2015. 53:233–45.
 Bergland, Christopher. “Is Gut Microbiome a New Biomarker for PTSD Susceptibility?” Psychology Today. Sussex Publishers. 27 Oct. 2017.