A study published in JAMA found that 99 percent of deceased NFL players tested had chronic traumatic encephalopathy, a degenerative brain disease associated with head injuries.
JAMA studied 202 former football players whose brains were donated to scientific research to determine if they had CTE, which can only be formally diagnosed with an autopsy. For the study, researchers examined the brains of 111 NFL players, 53 college players, 14 semi-professional players, 14 high school players, 8 Canadian Football League players and 2 prior to high school players. The study included players from every position on the field.
CTE was diagnosed in 87 percent of the 202 players studied. For former NFL players, the number was highest, with 110 out of 111 brains having CTE. The disease was also found in 48 of 53 college players and three of the 14 high school player brains.
The study also found that the severity of CTE pathology increased across the highest level of play. None of the high school players had severe CTE, while the majority (56 percent) of former college players and semi-professionals had severe pathology and 86 percent of former NFL players had severe CTE.
"There's no question that there's a problem in football. That people who play football are at risk for this disease," Ann McKee, MD, director of Boston University's CTE Center and coauthor of the study, told CNN. "And we urgently need to find answers for not just football players, but veterans and other individuals exposed to head trauma."