Posttraumatic stress disorder (PTSD) is a chronic debilitating psychiatric disorder characterized by symptoms of re-experience, avoidance, and hyperarousal that can arise immediately or many years after exposure to a traumatic event and injury. Although extensive research has been done over the past 30 years, the etiology of PTSD remains largely unknown. Several neurobiological systems have been implicated in the pathophysiology and vulnerability for developing PTSD; however, first-line pharmacotherapies are limited.