What causes PTSD? Researchers come closer to finding out

Katie Callahan Contributor
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Soldiers who experience brain trauma in combat are more likely to experience symptoms of post traumatic stress disorder, a four-year study of Marines found.

Researchers from San Diego and the U.S. Department of Veterans Affairs, studied the links between PTSD and mild traumatic brain injury (TBI) among Marines stationed at Camp Pendleton, the San Diego Union-Tribune reports.

The Marine Resiliency Study pulls off several firsts: it is the first to determine that brain trauma increases risk of PTSD, according to the lead investigator.

It’s also the first study to test Marine resiliency, the first to associate pain perception and anticipation and the first to compile pain images from fMRI scans of blast-injury Marines.

Dr. Dewleen Baker, the research director for the San Diego Veteran Affairs Center of Excellence for Stress and Mental Health, said researchers aimed to discover why some Marines are more resistant to PTSD than others.

“TBI was the strongest predictor of PTSD, even when controlling for pre-existing symptoms and combat intensity,” Baker told the Union-Tribune. “These finding may be used to identify individuals who may be at risk for developing PTSD and provide them with more immediate health care.”

The study was conducted from June 2008 to May 2012, with 1,648 Marines assessed before and after deployment at Camp Pendleton in southern California or at the San Diego VA Medical Center. The Marines were assessed on the basis of their total Clinician Administered PTSD Scale (CAPS) score, blood testing, physical response time, blood testing, and attention span.

“Moderate to severe brain trauma raised PTSD symptom scores by 71 percent,” the Union-Tribune reports. “Mild brain trauma increased PTSD scores by 23 percent.”

A little over half of the participants had prior brain injuries at the beginning of the study, while 19.8 percent sustained brain trauma through both assessments. Almost 90 percent of these cases were mild.

“Probability of PTSD was highest for participants with severe pre-deployment symptoms, high combat intensity, and deployment-related TBI. Traumatic brain injury doubled or nearly doubled the PTSD rates for participants with less severe pre-deployment PTSD symptoms,” stated the study, published online in the Journal of the American Medical Association.

second study found that “brain injury makes it more difficult to control acute pain,” researchers wrote.

The study, published online in the Translational Psychiatry journal in January, examined 36 males from the 1st Marine Division, half of whom had suffered from a past blast-related injury.

“Our findings are consistent with a notion that brain injury makes it more difficult to control acute pain,” the study found.

It included the work of UC-San Diego psychiatry associate professor Irina Strigo and the Veteran Affairs Healthcare System.

Strigo’s team placed 117 degree heat on the forearm of the Marines and used MRI scans to show the “invisible” damage to the brain stem from the blast injuries, the Union-Tribune reported.

Research teams also administered specific psychological testing and interviewing, a Brief Traumatic Brain Injury Screen, a brain injury and concussion history questionnaire and CAPS.

Marines with brain injuries who anticipated pain reported experiencing more pain. They were unable to regulate pain, making these subjects more susceptible to developing pain-related conditions.

“Individuals with TBI show a very high incidence of chronic pain. It is not necessarily due to primary injuries that occurred during combat. There is something more going on,” Strigo told the Union-Tribune.

Unable to distinguish particular causation and interaction problems for each Marine because of the intricacy of these pain receptor injuries, researchers hope to use animal models of these disorders in future studies to look for better medicine and alternative treatments that could eliminate drug use while still treating pain.