In the future, doctors may be able to predict whether some people are more at risk for developing PTSD
In the future, doctors may be able to predict whether some people are more at risk than others for developing posttraumatic stress disorder, suggests a recent study published in the American Journal of Psychiatry (AJP).
Why some warriors develop PTSD and others, exposed to the same stresses, do not is a problem that VA researchers and others have long been trying to understand. Lisa Shin, PhD, of Tufts University and Massachusetts General Hospital and a team of researchers, including VA's Natasha Lasko, PhD, and Michael Macklin, found a unique way to approach the problem. (Scott Orr, PhD, and Roger Pitman, MD, also members of the team, are retired VA employees.)
VA's Seattle Epidemiologic Research and Information Center (ERIC) maintains a registry of approximately 7,000 twins, both of whom served in the military during the Vietnam war era. The Vietnam Era Twin Registry is one of the largest national twin registries in the United States, and has been in existence for more than 20 years.
The team used brain imaging to study the brains of 12 Veterans, members of the registry, who had served in Vietnam and developed PTSD. The researchers compared the results to those of the Veterans' identical twins who did not serve in Vietnam and did not have the illness. The team also scanned the brains of 14 Veterans who served in Vietnam who did not develop PTSD, and their 14 twin brothers who did not serve in country and also did not develop the illness.
Some results of the study were published in AJP's September 2011 issue. The team found that an area of the brain called the dorsal anterior cingulate is activated more greatly in response to stimuli in the Veterans who developed PTSD and their twins, as opposed to the Veterans and their twins who did not develop PTSD. The dorsal anterior cingulate is a brain region that is thought to be involved in decision-making, performance monitoring, and other cognitive processes.
In other studies, Shin and her team have learned that the amygdala, a part of the brain that picks up on potential threats in the environment, is hyperactive in those with PTSD, and that the medial prefrontal cortex, which suppresses emotions and mediates conflicting thoughts, is underactive in those with the illness.
According to VA's National Center for PTSD (www.ptsd.va.gov), the disorder can occur after someone goes through a traumatic event like combat, assault, or a natural disaster. Most people have some stress reactions after a trauma, including upsetting memories of the event, increased jumpiness, or trouble sleeping. However, if the reactions don't go away over time, or disrupt everyday life, this can mean PTSD has developed.
There are four types of PTSD symptoms, including continually reliving the event that caused the problem; avoiding situations that recall the event; finding it hard to express feelings; and feeling jittery or always alert and on the lookout for danger. People with PTSD may also have other problems including drinking or drug problems; feelings of hopelessness, shame or despair; employment problems; and problems in their relationships with others.
Macklin, who works in the Research Department of the Manchester, New Hampshire, VA Medical Center, helped to recruit subjects for the recent study and guided them through the entire process. According to Macklin: "This study will bring some focus to the issue of how PTSD develops in Service members and Veterans. It has the potential to be useful to VA and the Department of the Defense in the future."
The team's findings could also lead to improved treatments for PTSD patients. Currently, VA treatments for PTSD include cognitive behavioral therapy; exposure therapy; group and family therapy, eye movement desensitization; and medication. Taking images of the brain before therapy starts could help determine which of these treatments will be most effective. (The Manchester VAMC, which has been internationally recognized for its studies of PTSD and other behavioral disorders, is engaged in another current study to evaluate the effectiveness of medications currently provided to Veterans with PTSD.)
This study was funded mainly by the U.S. Public Health Service (USPHS). VA supports a wide range of PTSD research programs, including biological investigations, clinical research, small interventional trials, and large multisite cooperative studies. Much of the research is conducted in partnership with federal agencies, such as USPHS, the National Institutes of Health, and the Department of Defense, as well as with academic, nonprofit, and private industry collaborators.
i Shin LM; Bush G; Milad MR; Lasko NB; Brohawn KH; Hughes KC; Macklin ML; Gold AL; Karpf RD; Orr SP; Rauch SL; Pitman RK: Exaggerated activation of dorsal anterior cingulate cortex during cognitive interference: a monozygotic twin study of posttraumatic stress disorder. Am J Psychiatry 2011; 168:979-985