A new JAMA study reveals chronic traumatic encephalopathy was present in a high number of brains of former football players. Researchers looked at the brains of former high school, college and NFL football players. Of the 202 brains analyzed, 177 showed signs of CTE. 110 of the 111 former NFL players' brains were diagnosed with CTE. Researchers say that, while the findings are significant, the findings could have limitations due to the players' families being motivated to donate the brains as a result of public awareness of the lasting effects of head injuries in football players.