A complex psychiatric syndrome that develops in response to trauma exposure. Individuals with PTSD experience intrusive recollections or reexperiencing of the traumatic event, avoidance of trauma reminders, emotional numbing, and hyperarousal. In addition, PTSD is associated with high rates of concomitant physical and mental health problems, increased health care use, and impairment in social and occupational functioning. Almost 7% of the general population and up to 30% of veterans meet lifetime criteria for PTSD. Indeed, PTSD is one of the most common psychiatric disorders, representing a significant and costly public health concern.