Nearly 92% of the former NFL players included a recent study were diagnosed with the degenerative brain disease Chronic Traumatic Encephalopathy (CTE), CBS News reports.
Researchers at Boston University's CTE center reported a 91.7% occurrence rate of CTE in the 376 studied as of Monday (February 6). The data for former NFL players was described as a sharp contract with an otherwise "extremely low population rate" of CTE in the general public, according to the researchers.
A 2018 study of brains donated to the Framingham Heart Study found that only one sample -- which belonged to a former college football player -- detected CTE among the 164 included. Boston University scientists cited "repetitive head impacts" as a key factor in common CTE cases among former football players.
Researchers did, however, clarify that there are selection biases in the brain bank included in the recent study and that the data doesn't suggest that nearly 92% of 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," said BU CTE Center director Dr. Ann McKee in a statement obtained by CBS News. "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 the individual's death. Last October, the U.S. National Institutes of Health has acknowledged the link between blows to the head and CTE in a landmark move in relation to the research of the neurodegenerative disease, the Guardian reported at the time.
The NIH -- which is the largest biomedical research agency in the world -- rewrote its official guidance on CTE after a group of 41 leading scientists, doctors and epidemiologists co-signed a letter addressed to the National Institute of Neurological Disorders and Stroke (Ninds), which cited a recent study published in the Frontiers in Neurology journal in July that noted the casual link between brain injuries experienced by abuse victims, soldiers and athletes.
CTE was initially recognized by experts in the 1950s and the link between the neurodegenerative disease and head injuries became "pretty clear" in 2014, though the official guidance had not been reflected until the announcement on October 24.