|Study Suggests Some Brain Injuries Reduce the
Likelihood of Post-Traumatic Stress Disorder
A new study of combat-exposed Vietnam War veterans shows that
those with injuries to certain parts of the brain were less likely
to develop post-traumatic stress disorder (PTSD). The findings,
from the National Institutes of Health (NIH) and the National Naval
Medical Center, suggest that drugs or pacemaker-like devices aimed
at dampening activity in these brain regions might be effective
treatments for PTSD.
PTSD involves the persistent reliving of a traumatic experience
through nightmares and flashbacks that may seem real. Twenty percent
to 30 percent of Vietnam vets (more than 1 million) have been diagnosed
with PTSD, and a similar rate has been reported among Hurricane
Katrina survivors in New Orleans. Public health officials are currently
tracking the disorder among soldiers returning from Iraq. Yet,
while war and natural disasters tend to call the greatest attention
to PTSD, it's estimated that millions of Americans suffer from
it as a result of assault, rape, child abuse, car accidents, and
other traumatic events.
Previous studies have shown that PTSD is associated with changes
in brain activity, but those studies couldn't determine whether
the changes were contributing to the disorder or merely occurring
because of it.
Jordan Grafman, Ph.D., a senior investigator at the National Institute
of Neurological Disorders and Stroke (NINDS), part of NIH, turned
to the Vietnam Head Injury Study (VHIS) to make that distinction.
The VHIS is a registry of Vietnam veterans who sustained penetrating
brain injuries (which are less common in Iraq compared to concussion
brain injuries). It has received support from the Department of
Defense, the Department of Veterans of Affairs and NIH, and is
currently supported by NINDS.
"If we could show that lesions in a specific brain region eliminated
PTSD, we knew we could say that the region is critical to developing
the disorder," says Dr. Grafman. The results of his study appear
online today in Nature Neuroscience.
Dr. Grafman and members of his lab, including neuropsychiatrist
Vanessa Raymont and postdoctoral fellow Michael Koenigs, studied
193 veterans registered with VHIS and 52 veterans with combat exposure
but no head injury. The participants were classified as either
having developed PTSD at some point in their lifetime or having
never developed PTSD. CT (computerized tomography) scans were used
to map their brain injuries.
By comparing the distribution of brain injuries between the PTSD
group and the non-PTSD group, the researchers found two regions
where damage was rarely associated with PTSD: the amygdala, a structure
important in fear and anxiety, and the ventromedial prefrontal
cortex (vmPFC), an area involved in higher mental functions and
In another level of analysis, the researchers compared the prevalence
of PTSD in subjects who had damage to either the amygdala or vmPFC,
subjects who had damage to other parts of the brain and non-head-injured
subjects. PTSD occurred in a similar fraction of subjects in the
last two groups — 40 percent and 48 percent, respectively.
In contrast, PTSD occurred in only 18 percent of subjects with
damage to the vmPFC and zero (out of 50) subjects with damage to
the amygdala. The occurrence of other anxiety disorders was not
affected by damage to the amygdala or vmPFC.
"It appears that if you have damage to either of those areas,
you're not likely to develop PTSD," says Dr. Grafman. The scientists
hypothesize that drugs designed to inhibit the activity of the
two structures might provide relief from PTSD. Deep brain stimulation,
a technique used to treat Parkinson's disease by modifying the
brain's electrical activity, might also prove useful against PTSD
if targeted to the amygdala or vmPFC.
Current treatments for PTSD include medications for anxiety and
depression, and therapy to help the person confront and deal with
traumatic memories. But these treatments vary in effectiveness,
a point underscored by the fact that many of the Vietnam veterans
in Dr. Grafman's study are still dealing with PTSD some 40 years
after the war.
Since the study examined only young men who served in Vietnam,
one question is whether the results will extend to women, children,
or people exposed to traumatic situations besides wartime combat.
Dr. Grafman says similar results probably will be found in those
other populations, given that previous studies had connected PTSD
to changes in the amygdala and vmPFC, and only some of those studies
involved war veterans.
is a component of the National Institutes of Health (NIH), and
is the nation's primary supporter of biomedical research on the
brain and nervous system.
The National Institutes of Health (NIH) — The Nation's
Medical Research Agency — includes 27 Institutes and
Centers and is a component of the U.S. Department of Health and
Human Services. It is the primary federal agency for conducting
and supporting basic, clinical and translational medical research,
and it investigates the causes, treatments, and cures for both
common and rare diseases. For more information about NIH and
its programs, visit www.nih.gov.
Koenigs M, Huey ED, Raymont V, Cheon B, Solomon J, Wasserman EM and
Grafman J. "Focal Brain Damage Protects Against Post-Traumatic
Stress Disorder in Combat Veterans." Nature Neuroscience,
published on-line December 23, 2007.