William Kerby was exposed to repeated blasts when he was deployed to Iraq as a Marine infantryman.
“For instance, we were setting off a charge on a door or a gate to blow it open, and there’s nowhere really to go, so you basically turn away from it within a few feet,” Kerby said. “You can feel that kind of concussion, that shockwave, as it goes through your body.”
Kerby was part of a study by Veterans Affairs Puget Sound Health Care System and UW Medicine examining the effects of repeated explosions on veterans with mild traumatic brain injury.
The study found that the more blasts they’re exposed to, the more the brain is affected. The findings were similar to brain changes found in boxers and football players.
Kerby remembers three explosions in Iraq that met the medical definition for mild TBI, which means they were strong enough to leave him either unconscious for a short time or stunned.
“If I was a betting guy I would bet that those three would be the ones that caused me the damage," Kerby said. But he was also subjected to many smaller blasts, 15-20 a day for 8-10 days, he estimated.
VA researcher David Cook said the work is important because being in an explosion is more nuanced than being hit on a football field, and the nature of modern warfare makes soldiers from Iraq and Afghanistan particularly vulnerable to mild TBI.
“Our soldiers are getting exposed over and over and over again,” Cook said. “And because they have much better body armor than they had in the Vietnam War they end up being able to tolerate blast exposures that in previous conflicts or under different circumstances might have more grievously injured them.”
A mild TBI injury from an explosion can result from a shockwave that rocks the body, shrapnel projectiles, or the victim’s head striking something as a result of the explosion.
Researchers tested 41 veterans with a history of mild TBI. They found the impacts were most noticeable in the lower regions of the cerebellum, the area of the brain that sits right at the base of the skull in the back of the head.
The cerebellum coordinates movement, helps control mood and cognitive functions, and helps multitask. Veterans like Kerby with mild TBI often report depression, irritability, impulsivity and problems managing certain tasks.
Cook hopes the findings will help improve treatments for the day-to-day symptoms as well as potential mid-life or late-life consequences, like Alzheimer's and chronic traumatic encephalopathy.
“Their symptoms are subtle and many of them are hidden. If we wait until veterans like Mr. Kerby and others are actually really in trouble, the cow will be out of the barn in terms of brain injury,” Cook said.
He said about 10 to 20 percent of service members who deployed to Iraq and Afghanistan came back with symptoms associated with repetitive blasts.
That's why he said there is so much emphasis now on understanding the issue. "If this does become a problem -- because we really don't know how bad it's going to get -- we don't want to be surprised at the end," Cook said.
The study is published in the journal, Science Translational Medicine.