PTSD Risk Rooted in Stress

PTSD Risk Rooted in Stress
Washington Post - United States
By Amanda Gardner
HealthDay Reporter
Tuesday, December 9, 2008; 12:00 AM

TUESDAY, Dec. 9 (HealthDay News) -- A decade-long study into post-traumatic stress disorder among combat veterans and their identical twins has yielded critical information on the root causes of this devastating condition.

The researchers found that both genetic and environmental factors increase the risk of developing post-traumatic stress disorder (PTSD). The work, to be presented Tuesday at the American College of Neuropsychopharmacology annual meeting in Scottsdale, Ariz., was sponsored by both the U.S. National Institute of Mental Health and the Veterans Administration.

"In addition to building our understanding of how PTSD comes to exist, we may have useful signs for PTSD prevention and treatment," study author Dr. Roger Pitman, a professor of psychiatry at Harvard Medical School, said during a recent teleconference on the research. "For example, persons with recognized PTSD risk factors may be best advised to avoid occupations that would have them serve in highly stressful situations, such as serving in military forces. Things acquired as a result of stress are more likely to be reversed by treatment and could be taken as targets of PTSD treatment."

Pitman's group studied more than 100 combat veterans of the Vietnam War, each of whom have an identical twin who did not serve in combat.

"We made the assumption that, because twins have the same genes and the same family upbringing, that the twin who did not serve in combat represents what the combat-exposed twin would be like except for the combat exposure," Pitman explained.

Prior to this research, experts had noted a smaller hippocampal volume (the hippocampus is a part of the brain involved in memory) in people with PTSD.

Now it appears that the smaller volume exists in both the exposed and unexposed twin, indicating that this may be a preexisting risk factor for PTSD.

"This suggests this 'fragile egg' hypothesis -- that some people are probably genetically a little bit less resilient [to PTSD] than other people," said Dr. Julie Fudge, an associate professor of psychiatry and neurobiology and anatomy at the University of Rochester Medical Center, in New York.

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