Post-Traumatic Stress Disorder (PTSD) is a specific form of anxiety that comes on after a stressful or frightening event.

While some stressors are a predictable part of most people's lives - for example, bereavement or chronic illness - others lie outside the range of these common experiences. These include hurricanes, floods and other natural disasters; airplane accidents and car crashes where considerable injury occurs; rape and assault; and armed combat, torture, and existence in a death...