The general public may have heard of this disorder occurring among Vietnam veterans, Bosnian civilians, or even the young witnesses to the recent spate of schoolyard shootings. Threat initially arouses the sympathetic nervous system, causing the person in danger to feel an adrenalin rush and go into a state of alert.
Threat also concentrates a person's attention on the immediate situation.
Finally, threat evokes intense feelings of fear and anger. These changes in arousal, attention, perception, and emotion are normal, adaptive reactions. They mobilize the threatened person for strenuous action, either in battle or in flight. Traumatic reactions occur when action is of no avail. When neither resistance nor escape is possible, the human system of self-defense becomes overwhelmed and disorganized.