Chronic traumatic encephalopathy (CTE) was found in 110 of 111 (99 percent) brains of deceased former National Football League players that were donated to scientific research, according to a study published in the medical journal JAMA. CTE, a neurodegenerative brain disease, was also neuropathologically diagnosed in 177 of the 202 players studied across all levels of play (87 percent). It was found in three of the 14 high school players and 48 of the 53 college players.
CTE is typically found in individuals who have been exposed to repeated head trauma, including veterans and football players. CTE can only be diagnosed with an autopsy. The JAMA study focused on football as the primary exposure to head trauma, whether or not the individual had exhibited symptoms while living. The study acknowledged the lack of a comparison group without which the study cannot offer an estimate on the overall risk of brain injury due to participation in football.