The same type of brain damage identified in 14 deceased professional football players has been pinpointed in veterans who endured bomb blasts in Iraq and Afghanistan - a finding that raises concerns that numerous other military personnel may be vulnerable to similar long-term impairments.
An international team of researchers led by Boston scientists said in a study published Wednesday that they discovered chronic traumatic encephalopathy, or CTE, in the brains of four veterans after their deaths, including three who had survived explosions from improvised explosive devices. The fourth had suffered multiple concussions in and out of the military.
The study was small and the findings need to be verified by other scientists, but specialists in combat trauma said the results are intriguing.
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The encephalopathy, identified during autopsies by a build-up of abnormal protein deposits in the brain, is a degenerative disease linked to repeated head traumas such as concussions. It was identified in the brain of former Chicago Bears safety Dave Duerson after his suicide last year and is suspected in the suicide earlier this month of former Patriots linebacker Junior Seau.
The disease has symptoms, such as depression, aggression, memory loss, and ultimately dementia, common with other traumatic brain injuries and also includes post traumatic stress disorder, or PTSD, which has been diagnosed in thousands of vets from Afghanistan and Iraq. Researchers said it’s possible that some of the symptoms of PTSD in veterans may be caused by CTE.
“There will be some with PTSD that have [encephalopathy], but we don’t know what percentage that may be,’’ said Dr. Ann McKee, a professor at Boston University School of Medicine and director of the Neuropathology Service for VA New England Healthcare System.
McKee, a senior coauthor of the study published online in Science Translational Medicine, also is a member of the BU team that has identified chronic traumatic encephalopathy in more than 50 former athletes, including professional, college, and high school football players, professional wrestlers, and boxers.
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In addition to identifying CTE in the brain tissue of four male veterans, aged 22 to 45, the researchers re-created an explosion in their lab that would be comparable to a blast typically encountered in battle and studied the effect on mice.
“We wanted to know whether exposure to a single blast would result in the same types of injuries that [McKee] was seeing years later in US military veterans,’’ said senior coauthor Dr. Lee Goldstein, an associate professor at the BU School of Medicine and College of Engineering. “The answer is yes, indeed.’’
Lee said all of the mice appeared to be healthy and looked normal after the blast but within weeks displayed learning and memory problems in finding their way in a maze, and their brains showed evidence of the abnormal proteins identified in people with CTE.
The researchers found the blast appeared to have permanently damaged the mice brain cells’ ability to communicate with each other. Blast winds from battlefield explosions can exceed 300 miles per hour, a force that whips a person’s head around like a bobblehead doll and is suspected by the scientists as the spark that ignites a cascade of destruction in the brain that ultimately may develop into CTE.
The researchers said when they immobilized the head and neck of mice during the blast, the animals did not display learning and memory problems, a finding that suggests better gear can be developed to protect soldiers from traumatic brain injuries.
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“The whole point of our work is to make lives better for veterans who suffer this injury,’’ McKee said.
Cynthia Smith, a US Department of Defense spokeswoman, said in an e-mail the agency is working on “the next generation of protective equipment to mitigate the effects of blast and other events that may lead to a [traumatic brain injury].’’
She said the department in the past three years has started programs to improve detection and treatment for service members with signs of brain injury, and is also funding studies to find better treatments.
Scientists not involved with the CTE study said that findings in mice may not translate the same to humans and that much more research needs to be done.
“This is a new area and we just don’t understand the connection yet - if there is a connection - between [traumatic brain injury] and CTE,’’ said Stuart Hoffman, who oversees traumatic brain injury research at the US Department of Veterans Affairs.
As for the thousands of veterans already diagnosed with post traumatic stress disorder, Hoffman said the agency is concerned about a possible link between that illness and CTE.
“That has been the $10 million question that the VA has been focusing on since 2008,’’ Hoffman said. “But there is no way for us to detect CTE in a living person now.’’
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David Hovda, director of the Brain Injury Research Center at the University of California, Los Angeles, said the blast experiments with mice will help other researchers unravel many remaining mysteries behind traumatic brain injuries.
“This is an important first step in trying to define what this problem is and that it’s not limited to the NFL, but also a problem in the military,’’ Hovda said.
Kay Lazar can be reached at klazar@globe.com.