Your great-grandfather’s World War I helmet that’s stuffed in the back of the closet could be just as effective at preventing brain injury from some blasts as a modern-day military helmet, a recently published study from Duke University researchers suggests.

The study is narrow in scope, looking only at effects from overhead explosions — a fact the researchers are first to admit. But it still raises questions about why today’s military helmet designs are not markedly better at protecting against certain kinds of shockwaves than those used more than 100 years ago.

The team of Duke biomedical engineers conducted their experiment by placing various styles of WWI helmets and modern helmets underneath a “shock tube,” which mimics an artillery shell exploding between 1 and 5 meters away.

The researchers then compared the impact on the helmets to the likelihood of brain injury from that level of pressure.

The results indicated the WWI helmets were just as likely to prevent brain damage as the designs being used today. (A soldier wearing any of the helmets is five to 10 times less likely to experience bleeding in the brain from an overhead blast than someone without a helmet, according to the study.)

The 1915 French “Adrian” helmet provided the most protection, researchers found, even more than that of modern helmets.

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Joost Op ‘t Eynde, a biomedical engineering Ph.D. student at Duke and the main author of the study, said he was surprised by the results because modern helmets have multiple layers of materials to prevent injury.

In contrast, helmets used in the Great War “were mostly just formed out of a thin layer of steel,” he said.

Little was known about traumatic brain injury at the time, so WWI helmets were designed to shield soldiers’ heads from shrapnel, not shockwaves. The protection it provided against brain injury was a fortunate byproduct.

Still, Op ‘t Eynde said he “would not suggest we use the helmets from WWI,” and quickly pointed out the benefits of modern versions over their older counterparts.

Today’s helmets are actually much better at preventing shrapnel wounds.

Plus, the study only looked at shockwaves coming from directly above — a scenario designed to mimic explosions above the infamous World War I trenches, or aerial attacks in today’s war zones.

The WWI helmets would do little if anything to protect against the shockwaves from roadside bombs or improvised explosive devices that often come from the ground upward or along a horizontal path.

The history of helmets

The effort to address brain injuries is only the latest shift in armor innovation, notes Mark Sheftall, a scholar-in-residence at the U.S. Army War College.

Helmets were widely used by the ancient Assyrians, Greeks and Romans to protect against arrows and blows from man-to-man combat. Employed in Europe across several different time periods, they largely fell out of use in the 18th and 19th centuries.

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For a time, gunpowder and bullets basically rendered “the major purpose of headgear obsolete, because it’s not going to be strong enough — in the way they were making it for thousands of years — to protect against modern bullets fired at close range,” he said. But artillery in World War I revived the need for helmets that could offer different kinds of protection.

Building a better helmet

Awareness surrounding traumatic brain injuries (TBIs) has grown substantially in the last century. The often invisible affliction has been linked to mood disorders and anxiety disorders, as well as a higher risk of suicide.

In recent years, U.S. conflicts in Afghanistan and Iraq have led to a dramatic rise in such injuries. Studies estimate that between 11 percent and 23 percent of U.S. military personnel who return from Iraq or Afghanistan likely have a TBI. More than 400,000 U.S. service members have been officially diagnosed with a TBI since 2000.

Despite a better understanding of the problem, veteran advocates and some defense analysts say helmets have not been adequately improved to guard against TBIs.

For military researchers, the difficulty is balancing a soldier’s safety with their combat effectiveness in an environment that is inherently dangerous.

U.S. military helmets are already required to withstand a variety of different scenarios, such as a bullet coming in at a certain speed, said Paul Scharre, a senior fellow at the Center for New American Security, a bipartisan nonprofit focused on national security and defense policies. “There is no requirement for blast exposure,” he said, adding that he thinks the Department of Defense is not doing enough to protect the men and women it sends onto the battlefield.

The U.S. Army has been developing blast protection standards for military helmets, then testing the helmets using simulations to ensure they meet the possible new requirements.

“We want to do better. We want to protect soldiers from all forms of traumatic brain injuries,” said Christopher Hoppel, a program manager at the Army Research Laboratory. He also critiqued the Duke research for being a “one-off study” that “wasn’t looking at the true blast resistance of helmets where a threat may come from other sides or other angles.”

For military researchers, the difficulty is balancing a soldier’s safety with their combat effectiveness in an environment that is inherently dangerous.

“There’s a tradeoff” between protecting against injury versus performance, said Rob DiLalla, team leader of the ballistic and blast protection team at the Combat Capabilities Development Command Soldier Center. “It would be great if we could put everyone in a bomb suit, but unfortunately, you’re going to diminish [the soldier’s] ability to shoot, move and communicate.”

Even if the U.S. military designs an effective upgrade, there will always be new challenges to address as combat continues its shift away from boots on the ground toward high-tech warfare, including drones.