CTE found in nearly 92% of former NFL players studied by Boston University

BOSTON - Researchers at Boston University on Monday reported finding CTE in 345 of the 376 former NFL players they have studied so far.

The school's CTE center said the 91.7% occurrence rate of CTE in ex-NFL players is a sharp contrast with the "extremely low population rate" of chronic traumatic encephalopathy in the general public. A 2018 study of brains donated to the Framingham Heart Study detected CTE in only 1 of 164 samples - the sole case belonged to a former college football player.

BU scientists say "repetitive head impacts" are believed to be the top risk factor for CTE, which is a degenerative brain disease.

The researchers caution that there are selection biases in the brain bank used for the study, and people shouldn't assume that nearly 92% of all current and former NFL players have CTE.

"While the most tragic outcomes in individuals with CTE grab headlines, we want to remind people at risk for CTE that those experiences are in the minority," BU CTE Center director Dr. Ann McKee said in a statement. "Your symptoms, whether or not they are related to CTE, likely can be treated, and you should seek medical care. Our clinical team has had success treating former football players with mid-life mental health and other symptoms."

A CTE diagnosis can only be confirmed after death. The center noted that two players diagnosed with CTE in the past year, former Philadelphia Eagles quarterback Rick Arrington and former Kansas City Chiefs defensive tackle Ed Lothamer, once played for the teams appearing in Super Bowl LVII on Sunday.

The NFL made changes to its concussion protocol last fall after it was criticized for the way Miami Dolphins quarterback Tua Tagovailoa's injury was handled.

Last July, BU doctors posthumously diagnosed the late NFL receiver Demaryius Thomas with CTE. His parents said he had suffered from erratic behavior and paranoia in his final years.