In post-traumatic stress disorder (PTSD), distressing symptoms occur after a frightening incident. For the most part, a person with this disorder must have experienced the event him or herself, or witnessed the event in person. The person may also have learned about violence to a close loved one. The event must have involved serious physical injury or the threat of serious injury or death.
Exposure to violence through media (news reports or electronic images) is usually not considered a traumatic incident for the purposes of this diagnosis, unless it is part of a person's work (for example, police officers or first responders to a violent event).
Some examples of traumas include:
Military combat (PTSD was first diagnosed in soldiers and was known as shell shock or war neurosis)
Serious motor vehicle accidents, plane crashes and boating accidents
Natural disasters (tornadoes, hurricanes, volcanic eruptions)
Robberies, muggings and shootings
Rape, incest and child abuse
Hostage-taking and kidnappings
Imprisonment in a concentration camp
In the United States, physical assault and rape are the most common stressors causing PTSD in women, and military combat is the most common PTSD stressor in men.
Stress of this severity does not automatically cause PTSD. In fact, most people who are exposed to terrible trauma do not develop this particular illness. The severity of the stressor does not necessarily match the severity of symptoms. Responses to trauma vary widely. Many people develop mental disorders other than PTSD.
Acute Stress Disorder is the term used when symptoms develop within the first month after a traumatic event. The term PTSD with delayed onset (or delayed expression) is used when symptoms surface six months or more after the traumatic event.
It is not clear what makes some people more likely to develop PTSD. Certain people may have a higher risk of PTSD because of a genetic (inherited) predisposition toward a more intense reaction to stress. Another way to put this is that some people have greater inborn resilience in response to trauma. A person's personality or temperament may affect the outcome after a trauma. Lifetime experience of other traumas (especially in childhood) and current social support (having loving and concerned friends and relatives) also may influence whether or not a person develops symptoms of PTSD.
People with PTSD are more likely to have a personality disorder. They also are more likely to have depression and to abuse substances.
Up to 3% or so of all people in the United States have full-fledged PTSD in any given year. Up to 10% of women and 5% of men have PTSD at some point in their lifetime. Although PTSD can develop at any time in life, the disorder occurs more frequently in young adults than in any other group. This may be because young adults are more frequently exposed to the types of traumas that can cause PTSD. The risk of developing PTSD is also higher than average in people who are poor, unmarried or socially isolated, perhaps because they have fewer supports and resources helping them to cope.