A study of brain tissue from 111 deceased former NFL players found that 110, or 99%, showed signs of the degenerative brain condition known as CTE, researchers said Tuesday.
The 111 former NFL players were part of a sample of 202 individuals who played football at the pre-high school, high school, collegiate or professional level.
It's the biggest update yet of an ongoing study of chronic traumatic encephalopathy, or CTE. The disease has been linked with repeated head blows and the results confirm that it can happen even in young players. But the report only reflects high occurrence in samples at a Boston brain bank and many donors contributed because of troubling symptoms before death.
“It is no longer debatable whether or not there is a problem in football – there is a problem,” Dr. Ann McKee, a neuropathologist who conducted the study, told the New York Times.
Of the 202 individuals examined, CTE was diagnosed in 177 former players or nearly 90 percent of brains studied.
In 2013, the NFL reached a settlement worth up to $1 billion with former players who alleged that the league misled or misinformed them about the risks associated with repeated head trauma.
Researchers still don't know how common it is in football or the general population. Some players with repeated concussions never develop it.
The report is in Tuesday's Journal of the American Medical Association.
The Associated Press contributed to this report.