New research suggests veterans who were exposed to bomb blasts may have brain damage comparable to those with traumatic brain injuries even if they don't report being hurt.
Veterans who have been in recent conflicts Iraq and Afghanistan often exposed to explosive forces from bombs and other devices; these are believed to have a detrimental effect on the brain, a Duke University Medical Center news release reported.
"Similar to sports injuries, people near an explosion assume that if they don't have clear symptoms - losing consciousness, blurred vision, headaches - they haven't had injury to the brain," senior author Rajendra A. Morey, M.D., associate professor of psychiatry and behavioral sciences at Duke University School of Medicine and a psychiatrist at the Durham Veterans Affairs Medical Center, said in the news release. "Our findings are important because they're showing that even if you don't have symptoms, there may still be damage."
Researchers looked at 45 U.S. veteran volunteers. The participants were split into three groups: "veterans with a history of blast exposure with symptoms of TBI; veterans with a history of blast exposure without symptoms of TBI; and veterans without blast exposure. The study focused on veterans with primary blast exposure, or blast exposure without external injuries, and did not include those with brain injury from direct hits to the head," the news release reported.
The researchers used a technique called Diffusion Tensor Imaging (DTI), which allows them to measure the amount of damage that has been inflicted on the brain; injury to white matter can cause significant cognitive problems. The white matter is the "connective wiring that links different areas of the brain," the news release reported.
Both groups of veterans who were near an explosion showed various patterns of white matter damage; the researchers also found a link between white matter and the ability to switch between mental tasks.
"We expected the group that reported few symptoms at the time of primary blast exposure to be similar to the group without exposure. It was a surprise to find relatively similar DTI changes in both groups exposed to primary blast," said Katherine H. Taber, Ph.D., a research health scientist at the W.G. (Bill) Hefner Veterans Affairs Medical Center and the study's lead author. "We are not sure whether this indicates differences among individuals in symptoms-reporting or subconcussive effects of primary blast. It is clear there is more we need to know about the functional consequences of blast exposures."
The research suggests that in the future brain injuries should be considered even in soldiers who did not report injury during an explosive blast.
"Imaging could potentially augment the existing approaches that clinicians use to evaluate brain injury by looking below the surface for TBI pathology," Morey said.
