Nearly all of the former National Football League players studied by the largest U.S. brain bank tested positive for the brain disease associated with concussions, Frontline reported Friday.
Chronic traumatic encephalopathy, or CTE, has been identified in 87 of 91 deceased players examined by researchers with the Department of Veterans Affairs and Boston University. That's about 96%. CTE is linked to repeated head injuries and can cause memory loss, depression and dementia, among other effects.
WATCH: NFL dogged by head injury issue
Player safety concerns have shaken the league in recent years as more research has suggested a connection between head trauma and long-term health issues. The lab has identified CTE in the brains of 131 of 165 examined individuals who played football at the high school level or above, according to the report.
As researchers can only definitively identify CTE posthumously, many of the players who donate their brains for testing may have had concerns about their brain health. Though that could skew the data, it remains "remarkably consistent," with past findings suggesting a link between the sport and brain disease, Dr. Anne McKee, the facility's director, told Frontline.
The NFL has channeled more resources into studying the effects of head injuries and reducing head injuries. Concussions in regular season games fell from 173 in 2012 to 112 last season, the league said in its 2015 safety report.
"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 NFL said in a statement. "We continue to make significant investments in independent research through our gifts to Boston University, the NIH and other efforts to accelerate the science and understanding of these issues."
Reacting to the report Friday on Twitter, former Green Bay Packers tight end Tom Crabtree said he received no education about CTE.