Post-traumatic stress disorder: pathogenesis, epidemiological characteristics, animal models, and potential therapeutic strategies

Abstract

Post-traumatic stress disorder (PTSD) is a complex neurobehavioral disorder that disproportionately affects military service members. The clinical presentation of PTSD is heterogeneous and may overlap with other psychiatric conditions. According to the Fifth Edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5), common symptoms include memory loss, mood and personality changes, impulsiveness, aggression, anxiety, and depression. The pathophysiological mechanisms underlying PTSD remain incompletely understood, although research implicates pathways involving the hypothalamic-pituitary-adrenal (HPA) axis, dysfunctional neural circuitry, neurochemical imbalances, neuroinflammatory processes, and genetic and epigenetic factors. Approximately 7% of the U.S. adult population has met the diagnostic criteria for PTSD in their lifetime, with a substantially higher prevalence of 12%-30% among military personnel. Multiple animal models, including single-stressor, intermediate complexity, social interaction, predator stress, and blast exposure paradigms, have been employed to investigate PTSD mechanisms. Current treatment strategies typically integrate pharmacotherapy and psychotherapy. Military service members are at increased risk for blast injuries, which frequently result in traumatic brain injury (TBI). Although some symptoms of TBI may resolve, approximately 20% of affected individuals develop new symptoms, including PTSD. Evidence suggests that exposure to blast shock waves (BSWs) serves as a critical trigger for the clinical manifestations of both TBI and PTSD. Recent studies have identified several mechanisms contributing to BSW-induced brain dysfunction, including intraneuronal accumulation of phosphorylated Tau (p-Tau), activation of the dynorphin/kappa opioid receptor, and activation of metabotropic glutamate receptor 2/3 signaling pathways. This review provides an overview of the clinical features, treatments, pathophysiology, and epidemiology of PTSD, as well as animal models and their limitations in replicating PTSD-like symptoms. It further examines the relationship between BSW exposure, brain injury, and PTSD, discusses animal models that simulate blast trauma and PTSD-like symptoms, and evaluates potential therapies to mitigate BSW-induced PTSD. Finally, the review addresses the limitations of current models and proposes future directions for elucidating the mechanisms linking brain trauma to PTSD.