In fact, a recent study done by a team of Duke University researchers finds that the 105-year-old “Adrian” helmet used by the French army in World War I can provide better blast protection than the Advanced Combat Helmet (ACH) widely used by the U.S. military.

…When those helmets were exposed to overhead blast waves that the 1915-era Adrian helmet outperformed the others. The Duke researchers point to the raised metal crest running from the front to the back of the Adrian helmet — a design feature also found on helmets used in those times by French firefighters — as a likely explanation for its superior protection from overhead blasts.

“The geometry of the helmet can make a big difference,” says Op ‘t Eynde. “I’m not sure a crest or something like it would work with a modern design, but just being aware of how the geometry might affect the way that the head and the brain might experience a shock wave is definitely something that I think should be kept in mind in helmet design.”

A World War I Vintage Helmet Bests A Modern Brain Bucket : NPR

huh