(PTSD), mental disorder that follows an occurrence of extreme psychological stress, such as that encountered in war or resulting from violence, childhood abuse, sexual abuse, or serious accident. The stressful event is usually followed by a period of emotional numbness and denial that can last for months or years. After that period, symptoms such as recurring nightmares, "flashbacks," short-term memory problems, insomnia, or heightened sensitivity to sudden noises may begin. In some cases outbursts of violent behavior have been observed. The usual treatment for PTSD is individual psychotherapy, including anxiety management, or group psychotherapy with others who have the disorder. Some antianxiety and antidepressant drugs are being studied for their effectiveness.

Certain traits (a history of depression, shyness, impulsivity) appear to heighten a person's risk of experiencing PTSD after a traumatic event. In those who do experience it, there is growing evidence that actual physical changes occur in the brain. The hippocampus, a structure that lies deep in the brain and that is associated with memory, has been found to be smaller in PTSD victims. It has been hypothesized that excesses of cortisol, a steroid hormone released during periods of extreme stress, may damage nerve fibers in the area or actually kill the nerve cells. However, the role of cortisol is not completely understood; studies of concentration camp survivors found abnormally low levels of cortisol rather than abnormally high levels.

Post-traumatic stress disorder was referred to as "shell shock" after World War I and as "battle fatigue" after World War II and was traditionally thought of as a condition of war veterans. Studies of Vietnam veterans and Nazi concentration camp survivors have added greatly to the knowledge of PTSD. The National Vietnam Veterans Readjustment Study (1988) estimated that 31% of the males and 27% of the females who served in the Vietnam War had symptoms of PTSD. Estimates of civilian populations put the rate of PTSD at 10% (women) and 5% (men) in the 15 to 54 age group. Childhood sexual abuse, sexual abuse, and assault are common causes of PTSD in both military and nonmilitary women. In 1989 the U.S. Congress created the National Center for Post-Traumatic Stress Disorder for the study and treatment of PTSD.

The Columbia Encyclopedia, Sixth Edition Copyright© 2004, Columbia University Press. Licensed from Lernout & Hauspie Speech Products N.V. All rights reserved.

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