Tests on deceased former professional American football players showed nearly all of them had a chronic traumatic brain disease, according to scientific research published Tuesday in the JAMA medical journal.
The disease, called chronic traumatic encephalopathy (CTE), is believed to be caused by repeated head trauma and has been known to cause memory loss, disorientation, depression and impaired judgement, among other symptoms.
Of the 202 total deceased former players studied for the report, which included high school, college and professional players, 177 were diagnosed with CTE. National Football League players seemed particularly prone to CTE, with 110 of the 111 former NFL players examined in the study being diagnosed with the disease.
"There's no question that there's a problem in football. That people who play football are at risk for this disease," study author and director of Boston University's CTE Center Dr. Ann McKee said. "And we urgently need to find answers for not just football players, but veterans and other individuals exposed to head trauma."
The study marks the most recent research published linking head trauma sustained while playing football to chronic brain injuries, though it is by no means conclusive.
As pointed out in the study, the brains examined for the research were donated by family members of football players who may have exhibited symptoms of chronic brain injury prior to death. This creates a selective sample that may not be representative of all football players.
The NFL released a statement praising the study for its role in advancing the science related to chronic head injuries and said it is working with “a wide range of experts to improve the health of current and former NFL athletes."
"There are still many unanswered questions relating to the cause, incidence and prevalence of long-term effects of head trauma such as CTE," the statement read.
Last year, the NFL acknowledged for the first time publicly a link between head blows sustained on the football field and brain disease and agreed to a $1 billion settlement to compensate former players who suffer from head trauma-related injuries.