RACHEL MARTIN, HOST:
We have news this morning about the struggle against brain injuries in the U.S. military. A high-tech program was designed to detect those injuries. Now NPR has learned that the Pentagon has suspended that program. Here's NPR's Jon Hamilton.
JON HAMILTON, BYLINE: In 2011, the Army began outfitting thousands of combat troops with devices known as blast gauges. Soldiers wore three of them, each slightly larger than a quarter. Kyle Sims was a Special Forces medic who helped deploy the gauges in Afghanistan. He remembers the first time he saw the gauges help a soldier.
KYLE SIMS: He comes in post-mission, he's complaining of a headache. The medic checks his gauges, sees that he's got an exposure, takes him over to the hospital, gets a good neuro exam. He gets diagnosed with a concussion.
HAMILTON: Sims, who now works with the company that makes the gauges, says that's just how they were supposed to work.
SIMS: And I thought that that was going to be the start of great things, you know, that we were really on the right path.
HAMILTON: Blast gauges measure the sudden increase in air pressure caused by an explosion. It's called overpressure and it's measured in pounds per square inch. A five psi overpressure can burst an eardrum, 100 psi can be fatal. Somewhere in between is probably where most concussions occur. Right away the gauges turned up something interesting. That soldier who came back with a concussion? He didn't encounter a bomb. Sims says he'd been operating a shoulder-fired rocket.
SIMS: And that shoulder-fired rocket actually gave him a pretty significant overpressure exposure just because he was firing it from a bit of a confined space.
HAMILTON: The pressure wave from the weapon probably got amplified, so this soldier's brain took a hit just from firing his own weapon. David Borkholder is an engineering professor at the Rochester Institute of Technology and the founder of BlackBox Biometrics, which makes the gauges. He says blast gauge data from Afghanistan showed a clear pattern.
DAVID BORKHOLDER: The majority of exposures were not from IEDs, improvised explosive devices, as you might expect. They were actually from blast-intensive weapon systems, so things like recoilless rifles, shoulder-fired rockets, artillery and mortars.
HAMILTON: Firing something like a large recoilless rifle generates a powerful pressure wave both in front of and behind the weapon.
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HAMILTON: Borkholder says the pressure waves are usually less intense than the ones from a bomb, but exposures are far more common.
BORKHOLDER: A service member on the training range may experience 30 to 300 exposures per day, multiple days per week.
HAMILTON: In other words, many troops are routinely exposed to overpressure as part of their job. And research in the past few years suggests that lots of small exposures can add up. Despite what the blast gauge program turned up, the military considers it a disappointment. That's because the Department of Defense had a very specific goal - identifying troops with brain injuries caused by the blast wave from a bomb. And Borkholder says the military soon realized that an exposure high enough to cause a concussion in one person might have no effect on someone else.
BORKHOLDER: Their objective was to have this device basically predict if the person had a concussion and it wasn't able to do that.
HAMILTON: So the Army quietly warehoused the gauges. When NPR contacted the Army, a spokesman said it would be early next year before they could respond to an interview request. But in a November letter to Representative Louise Slaughter of New York, the secretary of the Army said it stopped using the gauges because they did not provide, quote, "consistent or reliable data."
PETER CHIARELLI: I think it's a mistake. I think it's a huge mistake.
HAMILTON: Retired Gen. Peter Chiarelli was the Army's vice chief of staff before retiring in 2012. He says the military should treat overpressure much the way it treats other dangerous environmental factors like radiation.
CHIARELLI: It's absolutely essential that we collect data in all instances where soldiers receive overpressure from whatever the blast, if it's in training or combat or anything.
HAMILTON: Then, Chiarelli says, the military would know the total dose of overpressure each service member received during their time in service.
CHIARELLI: Those numbers could play a very, very important role in helping us understand why an individual has negative effects from a concussion or why an individual develops one or the other neurodegenerative diseases that seem connected with concussion.
HAMILTON: A clear link between overpressure and brain diseases like Alzheimer's could prove costly to the military and veterans' health systems. So I asked Chiarelli whether he thinks that might be a factor in the military's decision not to gather more blast gauge data.
CHIARELLI: I'm not going to go that far. I would hope not. I would hope not.
HAMILTON: The Department of Defense says it's testing a new generation of blast gauges that are more sensitive and easier to maintain, but it has made no commitment to deploying them. Jon Hamilton, NPR News.
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