The Gut–Brain Axis in Post-Traumatic Stress Disorder: From Biological Mechanisms to Microbiome-Based Therapeutic Strategies—A Narrative Review

Post-traumatic stress disorder (PTSD) is a debilitating psychiatric condition that impairs psychological functioning and increases susceptibility to various chronic illnesses, including inflammatory, metabolic, and cognitive disorders. Recent advances in neuroscience and microbiology have identified the brain–gut–microbiota axis as a key mediator of neuroimmune and neuroendocrine regulations, providing new insight into the pathophysiology of PTSD. This review synthesizes current findings from preclinical and clinical studies on gut microbiome alterations in PTSD, highlighting the underlying mechanistic pathways. Dysbiosis in PTSD is associated with immune dysregulation, altered neuroendocrine signaling, and neurotransmitter imbalances. Animal models, particularly those using the single prolonged stress paradigm, have demonstrated behavioral and microbial changes that mirror the characteristics of human PTSD. Human studies have revealed reduced abundance of beneficial bacterial taxa and increased inflammation-associated genera in patients with PTSD. Although emerging evidence supports the role of gut microbiota in PTSD, further research is needed to establish causal relationships and optimize microbiome-targeted therapies. Overall, the gut microbiome offers a novel and potentially modifiable target for the prevention and treatment of PTSD.