Sgt. John Wagley fires an AT4 anti-tank missile during a training session at Camp Fuji, in Japan. Studies find that some who fire these weapons repeatedly have short-term problems with memory and thinking. It’s still not clear, scientists say, whether those temporary changes can lead to permanent deficits.

Sgt. John Wagley fires an AT4 anti-tank missile during a training session at Camp Fuji, in Japan. Studies find that some who fire these weapons repeatedly have short-term problems with memory and thinking. It’s still not clear, scientists say, whether those temporary changes can lead to permanent defici