WEDNESDAY, May 3, 2006 (HealthDay News) -- A study of Vietnam veterans and their identical twins suggests that minor neurologic problems may make people more susceptible to post-traumatic stress disorder(PTSD).
The researchers found that both veterans with PTSD and their identical twins have the same minor neurologic deficits, or abnormalities. On the other hand, veterans and their twins who don't suffer from the debilitating psychological condition don't have these deficits.
PTSD is an anxiety disorder involving nightmares, flashbacks and panic attacks linked to event "triggers" that develop after exposure to combat or other extremely disturbing events.
Some researchers have argued that the traumatic events experienced can actually cause brain deficits that lead to PTSD. Others think that some preexisting brain abnormalities may increase the risk of developing PTSD after a traumatizing event.
The findings in this study suggest that the deficits aren't caused by exposure to traumatic events, but exist before the event, predisposing people to PTSD.
The report appears in the May issue of the Archives of General Psychiatry.
"People with PTSD have subtle evidence of neurological impairment," said lead researcher Dr. Roger K. Pitman, a professor of psychiatry at Harvard Medical School. "Vietnam combat veterans had these impairments as did their identical twins, who did not serve in Vietnam," he added.
In its study, Pitman's team looked at 49 Vietnam veterans who had experienced combat in Vietnam and their identical twins, who had not. Among these men, 25 had PTSD and 24 had never had PTSD. All the men were given a score of "0" to "3" on each of 45 neurologic tests, such as copying drawings of figures. A higher score indicated the presence of neurologic problems associated with behavior, coordination and learning.
Men with PTSD had higher scores than those without PTSD. The twins of these men, who had not been in combat, also had significantly higher scores. However, the twin sets who did not have PTSD did not show these problems, the researchers found.
"People who, for some reason, have subtle neurological impairment may be more at risk for developing PTSD when they have a traumatic event," Pitman said. "These abnormalities are very subtle and do not amount to brain damage, and not everybody who has PTSD has these abnormalities," he added. "Anybody can get PTSD if the situation is stressful enough."
Whether this finding will help treat people with PTSD isn't clear, Pitman said. "You could argue that people with subtle neurological impairments shouldn't be put in stressful situations. But, I think there would be a lot of practical impairments to doing that."
One expert agrees that these neurological problems or even genetics can predispose someone to developing PTSD.
"This finding is being replicated in a number of ways," said Joseph Boscarino, an expert in PTSD and a senior investigator at the Geisinger Clinic in Danville, Pa. "There is an underlying vulnerability that is probably genetically based for PTSD and other mental disorders."
Boscarino noted that for PTSD to develop, the genetic predisposition needs an actual traumatic event to activate it. "You have this genetic vulnerability, but if you don't go to combat or experience stressors in the environment, you are not going to develop PTSD and the problems that go along with it," he said.
Another expert thinks these findings add to the general knowledge about PTSD.
"This study is another important step in clarifying one of the most basic and difficult questions to answer in PTSD -- that is, of the many biological findings now documented in PTSD, which are caused by PTSD and which cause PTSD?" said Dr. Randall D. Marshall, director of Trauma Studies and Services at New York State Psychiatric Institute and an associate professor of clinical psychiatry at Columbia University College of Physicians and Surgeons.
"This finding, that neurological soft signs appear to have genetic origins and therefore are likely to pre-date trauma exposure and PTSD, helps to further clarify our understanding of the complicated interaction of vulnerability and trauma exposure that can result in PTSD," Marshall said.
More information
For more on PTSD, visit the U.S. National Institute of Mental Health.
