Washington: Damage to the brain may still occur even if symptoms of traumatic brain injury are not present, scientists, including one of Indian origin, suggest.
Veterans exposed to explosions who do not report symptoms of traumatic brain injury (TBI) may still have damage to the brain's white matter comparable to those with TBI, researchers said.
The findings suggest that a lack of clear TBI symptoms following an explosion may not accurately reflect the extent of brain injury, they said.
"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," said senior author Rajendra A Morey, associate professor at Duke University School of Medicine and a psychiatrist at the Durham Veterans Affairs Medical Center.
"Our findings are important because they are showing that even if you don't have symptoms, there may still be damage," said Morey.
Researchers evaluated 45 US veterans who volunteered to participate in the study.
The veterans 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 excluded those with brain injury from direct hits to the head.
To measure injury to the brain, the researchers used a type of MRI called Diffusion Tensor Imaging (DTI). DTI can detect injury to the brain's white matter by measuring the flow of fluid in the brain.
White matter is the connective wiring that links different areas of the brain. Injury to white matter can impair the brain's communication network and may result in cognitive problems, researchers said.
Both the groups who were near an explosion, regardless of whether they had TBI symptoms, showed a significant amount of injury compared to the veterans not exposed to a blast.
The injury was not isolated to one area of the brain, and each individual had a different pattern of injury.
Using neuropsychological testing to assess cognitive performance, the researchers found a relationship between the amount of white matter injury and changes in reaction time and the ability to switch between mental tasks.
However, brain injury was not linked to performance on other cognitive tests, including decision-making and organisation, said researchers.
The study was published in the Journal of Head Trauma Rehabilitation.