Texas A&M Researchers Set to Study Biological Components of PTSD

From the Bryan-College Station [TX] Eagle:

Over the next year and a half, a team of Texas A&M professors and other researchers are expected to follow troops who recently returned from Iraq and Afghanistan - trying to gain insight into why some people seem to be more susceptible to post-traumatic stress disorder than others.

The team, led by associate professor Keith Young, received $3 million from Congress earlier this year to start the study. And if the current incarnation of the 2008 fiscal year budget is approved by the Senate, the group will receive an additional $3.4 million.

The idea for the project - which will include ongoing interviews with 1,400 troops from Fort Hood set to begin this winter - was sparked by research Young completed in 2004. During that study, researchers were surprised to find that the brain's thalamus was abnormally large in people who had experienced major depression, he said.

They then detected a gene variant that caused the enlargement in some people.

The thalamus is used by the body to interpret threatening visual stimuli, facial expressions and fearful emotions, Young said. So those with the heightened "automatic threat detection system" could be more vulnerable when dealing with stressors that lead to PTSD, the team has theorized.

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Details on the team's original findings:

In 2004, Drs. Young and Hicks, along with collaborators at The University of Texas Southwestern Medical Center at Dallas, published a paper that described substantial changes in the anatomy of the brain in people suffering from major depression.

“It was the first time that findings like this were shown,” Dr. Young said. “In the brains of people that experienced major depression, the thalamus was larger. At the time, most scientists were focusing on neurochemical reasons for depression, not anatomical factors, and almost all of those studying anatomy were looking for brain defects, not enlargements.”

Based on their findings, Drs. Young and Hicks followed up with a study that sought to discover if a genetic alteration was responsible for the change. What they found was remarkable.

The inheritance of a common serotonin transporter (SERT) gene variant was found to be involved in enlargement of the pulvinar nucleus of the thalamus, which is involved in interpreting threatening visual stimuli, facial expressions and fearful emotions. The enlarged pulvinar may enhance the brain’s “automatic threat detection system,” making some people more vulnerable when exposed to stress and trauma.

Back to the Eagle for what's to come:

The study is critical, Young said, "because we really don't understand what brain changes predispose people" to PTSD. "Once we understand, I think we're going to do a much better job at treating and determining which people are at risk for PTSD," he said.

In addition to the in-depth interviews, the study will include brain scans to look for possible post-combat changes in the brain structure and examination of cadaver brains from donors who had PTSD. Young said the group also plans to develop an animal model to test new ways of treatment. Rats can be subjected to extreme stressors using a "forced swim test." Trauma from the procedure tends to cause changes in the rats' neurochemistry that make the animals look like they're depressed, Young said, explaining they can become more easily startled and have an exaggerated response to loud noises.

Troops returning from combat zones often report similar responses.

The group also hopes to conduct a large clinical trial for fluoxetine, a drug commonly known as Prozac that has been widely used for depression. It's also used somewhat for PTSD, but it has never been tested on active-duty troops, Young said. "Particularly, we're looking to see if we can intervene very early after PTSD symptoms appear," he said, explaining that researchers hope early use of the drug could help prevent onset of the disorder.

The study isn't expected to result in people being screened or barred from combat, Young said. "Perhaps what we can do is identify a profile of someone, [and] if they become initially ill we can know how to treat them," he said. "Maybe we can know someone needs to be watched more carefully."

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