(Reuters) – All but four of 91 former National Football League (NFL) players who donated their brains for research were diagnosed with chronic traumatic encephalopathy (CTE) linked to concussion and head trauma, according to the Concussion Legacy Foundation.
The study was conducted by the United States Department of Veteran Affairs and Boston University, the Foundation said on its website.
The results of the study were first reported September 18 by the documentary TV program “Frontline.”
According to a program news release (http://to.pbs.org/1KGsuqO), 40% of those who tested positive were the offensive and defensive linemen who come into contact with one another on every play of a game.
“That finding supports past research suggesting that it’s the repeat, more minor head trauma that occurs regularly in football that may pose the greatest risk to players, as opposed to just the sometimes violent collisions that cause concussions,” the release explains.
The results do not necessarily mean that nearly all former NFL players have CTE because it was not a random sampling. The players who donated their brains did so because they had concerns.
The NFL said it was continuing efforts to reduce injuries.
“We are dedicated to making football safer and continue to take steps to protect players, including rule changes, advanced sideline technology and expanded medical resources,” the league said in a statement.
“We continue to make significant investments in independent research … and other efforts to accelerate the science and understanding of these issues.”
In April, the NFL settled a lawsuit brought by about 5,000 former players who accused the leaue of covering up the dangers of concussions.