Researchers may be closing in on a way to check athletes while they’re alive for signs of a degenerative brain disease that’s been linked to frequent head blows.

Experimental scans found higher levels of an abnormal protein tied to the disease in a study of former National Football League players who were having mood and thought problems.

It’s the first time a major study has tested these scans for detecting chronic traumatic encephalopathy, or CTE, which is only diagnosed now after death.

Doctors are searching for a way to tell when players, veterans or others with concussions are at risk for permanent damage. The scans can’t be used yet to say a player does or does not have CTE.

The New England Journal of Medicine published the results Wednesday.

Marilynn Marchione, The Associated Press