Shell shock was identified during World War I as a condition that causes soldiers to become dazed after being near explosions. Symptoms may appear weeks after exposure and there are no outward signs of injury. Naturally, this was regarded as a psychological rather than physical disorder.
But according to a story in today’s Science Magazine podcast, there is increasing evidence that shell shock is caused by physical trauma to the brain. One theory is that compression waves from the explosion hit the torso and transfer pressure to the brain via the circulatory system. If this theory is true, improved head gear will not help but improved body armor might.