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Researchers have identified a new pattern of brain damage in soldiers exposed to explosions, offering insights into how such blasts may damage the brain, according to a study published Thursday in The Lancet Neurology.

Eight men who were exposed to single or multiple explosive blasts developed scarring in similar regions of the brain, in patterns that author Dr. Daniel Perl said have not been associated with other brain disorders.

“This is a critical issue for the Department of Defense,” Perl said. As a professor of pathology at the Uniformed Services University of the Health Sciences, he estimates that thousands of soldiers may have experienced such blast injuries, and he has spent the past four years trying to understand how they impact the brain.


Perl said that the scarring occurred at boundaries between different parts of the brain, such as the junction between grey and white matter. Grey matter sits on the periphery of the brain and white matter on the interior.

This makes sense from a physics perspective, he said, because when blast shockwaves travel through different materials, they cause damage at the interface.


Boston University researcher and CTE center Director Dr. Ann McKee said that she has seen similar patterns of brain scarring in individuals who were exposed to multiple concussions but not explosive blasts, casting some doubt on whether the patterns observed by Perl are specific to blast injuries.

Regardless, this study nearly doubles the number of published cases of blast-associated traumatic brain injury, authors of an accompanying editorial point out. Researchers say it’s challenging to collect enough brain samples to run large studies.

Early in the wars in Afghanistan and Iraq, “exposure to blast was not really reported up the chain,” Perl said. Instead, soldiers shrugged it off — much like concussions used to be largely ignored in sports. So, researchers wouldn’t know whom to study to see the impact of these blasts.

And for soldiers who die from the blasts, the families who would be providing consent for the soldiers to be studied “are preoccupied with the very obvious other logistical things associated with the loss of a loved one,” said Dr. Geoffrey Grammer, an army colonel. 

Grammer, also the national director of the Department of Defense’s Defense and Veterans Brain Injury Center, called the results “intriguing and thought-provoking.” Grammer and Perl are part of the same research center at the Uniformed Services University, but Grammer was not involved in the new study.

Perl, who directs the Maryland brain bank where the samples were stored, said he hopes media attention, as well as increased outreach, will boost donations to the bank. That, he said, would allow researchers to determine how often this type of scarring occurs, and how powerful a blast must be to trigger it.  

“We need to study more cases,” Perl said.