Signs of trauma documented in living brains

For the first time, scientists have seen the ravages of repeated concussions in the brains of living people. Brain scans of five retired National Football League players reveal unusual deposits of an ominous protein called tau that used to be identifiable only through autopsy. Tau is a hallmark of chronic traumatic encephalopathy, a disease that causes the gradual appearance of mental and emotional problems in people who have experienced repeated brain trauma.