Chronic traumatic encephalopathy (CTE) – a neurodegenerative brain disease – was found in nearly all of the donated brains of National Football League (NFL) players examined in a new study by the Journal of the American Medical Association.
The study suggests that the correlation between football and the disease is distressingly strong: of the 111 NFL football players, 110 showed the presence of CTE. CTE is frequently found in individuals who have suffered repeated head trauma. Its symptoms include memory loss, impaired judgment, aggression, depression, anxiety and impulse control issues. CTE can only be diagnosed after death.
The findings suggest that the presence of CTE begins early for football players. At the high school level, three out 14 football players show signs of CTE. The incidence of CTE rises in college football players to 48 out of 53 players with CTE, and is goes up from there at the professional levels.
"Families don't donate brains of their loved ones unless they're concerned about the person," Dr. Ann McKee, the study's senior author, told NPR. "So all the players in this study, on some level, were symptomatic. That leaves you with a very skewed population ... So while we don't know the exact risk and we don't know the exact number, we know this is a problem in football."
The NFL, which has funded portions of Dr. McKee's research in the past not including the current study, said: "Case studies such as those compiled in this updated paper are important to further advancing the science and progress related to head trauma ... As noted by the authors, there are still many unanswered questions relating to the cause, incidence and prevalence of long-term effects of head trauma such as CTE."
In 2013, the NFL settled a concussion lawsuit involving thousands of former NFL players for $765 million (USD). Since then, the league claims it has instituted new policies to better protect its players from injuries that may cause neurodegenerative diseases such as CTE. It was a benchmark settlement, in part because the NFL previously denied the proliferation of brain diseases among professional football players.
McKee said that she does not expect the NFL to fund CTE research in the future, because "the results are considered too damaging."