Post Traumatic Stress Disorder (PTSD) develops when a person either witnesses or experiences a traumatic event. Common examples of trauma include military combat, personal assault, violent crime, natural disasters, or being diagnosed with a life-threatening illness. In response, the person experiences intense anxiety and feels as if he or she is reexperiencing the traumatic event. This reexperiencing can take several forms, including nightmares and flashbacks. As a result, situations that serve as reminders of the event are avoided and/or the individual will attempt to numb the PTSD symptoms. The individual may also experience difficulty focusing and concentrating, sleep disturbance, or an exaggerated startle response. PTSD often can be categorized into three groups: Acute (when the symptoms last less than 3 months), Chronic (when symptoms last 3 months or longer), and With Delayed Onset (when symptoms do not occur until at least 6 months have passed between the time the trauma occurred and the onset of the symptoms).

PTSD can occur at any age. Although symptoms usually begin within 3 months of the traumatic event, the onset of symptoms may not appear for several years. The symptoms of PTSD and the severity of the symptoms may vary over time. An increase in either the amount of symptoms or the severity may occur in response to reminders of the trauma, experiencing a new trauma, or other life stressors.

Within the general population, PTSD occurs in approximately 8% of American adults. Rates are higher within “at-risk” populations, including survivors of rape or military combat.