Pierre-Jean Hamilton

The study used magnetic resonance imaging to scan the brains of more than 500 members of special operations units, which are often near explosions.

The scan showed that brain aneurysms were three times as common in individuals with high levels of blast exposure compared with those who had relatively low exposure.

The abnormality was found in 9.5% of the high-exposure group compared with just 2.7% in the low-exposure group.

Aneurysms are weak or bulging spots in an artery that are prone to rupture and can cause deadly bleeding in the brain.

Researchers suspect that blast waves damage the walls of an artery by stretching the vessel beyond its limits.

John Hamilton, NPR News.