(PTSD) may occur soon after a major trauma, or can be delayed for more than six months after the event. When it occurs soon after the trauma it usually resolves after three months, but some people experience a longer-term form of the condition, which can last for many years. PTSD can occur at any age and can follow a natural disaster such as flood or fire, or events such as war or imprisonment, assault, domestic abuse, or rape. The terrorist attacks of Sept. 11, 2001, in the U.S. may have caused PTSD in some people who were involved, in people who witnessed the disaster, and in people who lost relatives and friends. These kinds of events produce stress in anyone, but not everyone develops PTSD. We do not know what causes PTSD, but psychological, genetic, physical, and social factors are involved. PTSD alters the body’s response to stress by affecting stress hormones and neurotransmitters (chemicals that transmit information between our nerves). Previous exposure to trauma may increase the risk, which suggests that this kind of a reaction may be a learned response. Having good social support helps to protect against developing PTSD. In studies of Vietnam veterans, those with strong support systems were less likely to develop PTSD than those without social support. People with PTSD re-experience the event again and again in at least one of several ways. They may have recurrent distressing dreams and recollections of the event, a sense of reliving the experience (referred to as flashbacks), and/or become very distressed around the time of events that symbolize the event (such as anniversaries).
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