Post-Traumatic Stress Disorder
NIMH Web Publication
National Institute of Mental Health (NIMH)
January 1, 2001 (Updated October 1, 2001, 2001
stress disorder (PTSD) is an anxiety disorder that can develop
after exposure to a terrifying event or ordeal in which grave physical
harm occurred or was threatened. Traumatic events that may trigger PTSD
include violent personal assaults, natural or human-caused disasters,
accidents, or military combat.
Among those who may experience
PTSD are military troops who served in the Vietnam and Gulf Wars; rescue
workers involved in the aftermath of disasters like the terrorist
attacks on New York City and Washington, D.C.; survivors of the Oklahoma
City bombing; survivors of accidents, rape, physical and sexual abuse, and
other crimes; immigrants fleeing violence in their countries; survivors of
the 1994 California earthquake, the 1997 North and South Dakota floods,
and hurricanes Hugo and Andrew; and people who witness traumatic events.
Family members of victims also can develop the disorder. PTSD can occur in
people of any age, including children
Many people with PTSD
repeatedly re-experience the ordeal in the form of flashback episodes,
memories, nightmares, or frightening thoughts, especially when they are
exposed to events or objects reminiscent of the trauma. Anniversaries of
the event can also trigger symptoms. People with PTSD also experience
emotional numbness and sleep disturbances, depression,
and irritability or outbursts of anger. Feelings of intense guilt are also
common. Most people with PTSD try to avoid any reminders or thoughts of
the ordeal. PTSD is diagnosed when symptoms last more than 1 month.
Physical symptoms such as
headaches, gastrointestinal distress, immune system problems, dizziness,
chest pain, or discomfort in other parts of the body are common in people
with PTSD. Often, doctors treat these symptoms without being aware that
they stem from an anxiety disorder.
Facts About PTSD
An estimated 5.2
million American adults ages 18 to 54, or approximately 3.6 percent of
people in this age group in a given year, have PTSD. 1
About 30 percent of
Vietnam veterans developed PTSD at some point after the war. 2
The disorder also has been detected among veterans of the Persian Gulf
War, with some estimates running as high as 8 percent. 3
More than twice as many
women as men experience PTSD following exposure to trauma. 4
Depression, alcohol or
other substance abuse, or other anxiety disorders frequently co-occur
with PTSD. 5 The likelihood of
treatment success is increased when these other conditions are
appropriately diagnosed and treated as well.
Treatments for PTSD
PTSD can be extremely debilitating.
Fortunately, research—including studies supported by NIMH and the
Department of Veterans Affairs (VA)—has led to the development of
treatments to help people with PTSD.
Studies have demonstrated the efficacy of
cognitive-behavioral therapy, group therapy, and exposure therapy, in
which the person gradually and repeatedly re-lives the frightening
experience under controlled conditions to help him or her work through the
Studies also have found that several types of medication, particularly the
selective serotonin reuptake inhibitors and other antidepressants, can
help relieve the symptoms of PTSD. 8
Other research shows that giving people an
opportunity to talk about their experiences very soon after a catastrophic
event may reduce some of the symptoms of PTSD. A study of 12,000
schoolchildren who lived through a hurricane in Hawaii found that those
who got counseling early on were doing much better 2 years later than
those who did not. 9
Research is continuing to
reveal factors that may lead to PTSD. People who have been abused as
children or who have had other previous traumatic experiences are more
likely to develop the disorder.10
In addition, it used to be believed that people who tend to be emotionally
numb after a trauma were showing a healthy response; but now some
researchers suspect that people who experience this emotional distancing
may be more prone to PTSD.11
Studies in animals and humans
have focused on pinpointing the specific brain areas and circuits involved
in anxiety and fear, which are important for understanding anxiety
disorders such as PTSD.12 Fear,
an emotion that evolved to deal with danger, causes an automatic, rapid
protective response in many systems of the body. It has been found that
the fear response is coordinated by a small structure deep inside the
brain, called the amygdala.
The amygdala, although relatively small, is a very complicated structure,
and recent research suggests that different anxiety disorders may be
associated with abnormal activation of the amygdala.
People with PTSD tend to have
abnormal levels of key hormones involved in response to stress.13
When people are in danger, they produce high levels of natural opiates,
which can temporarily mask pain. Scientists have found that people with
PTSD continue to produce those higher levels even after the danger has
passed; this may lead to the blunted emotions associated with the
Some studies have shown that
cortisol levels are lower than normal and epinephrine and norepinephrine
are higher than normal. Norepinephrine is a neurotransmitter released
during stress, and one of its functions is to activate the hippocampus,
the brain structure involved with organizing and storing information for
This action of norepinephrine
is thought to be one reason why people generally can remember emotionally
arousing events better than other situations. Under the extreme stress of
trauma, norepinephrine may act longer or more intensely on the
hippocampus, leading to the formation of abnormally strong memories that
are then experienced as flashbacks or intrusions. Since cortisol normally
limits norepinephrine activation, low cortisol levels may represent a
significant risk factor for developing PTSD.
Research to understand these
neurotransmitter systems involved in memories of emotionally charged
events may lead to the discovery of drugs or psychosocial interventions
that, if given early, could block the development of PTSD symptoms.
For More Information
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All material in this fact sheet
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from the Institute. Citation of the source is appreciated.
NIH Publication No. 01-4597
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Updated: October 01, 2001
Posted: January 16, 2001
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