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He made the announcement in the most Dale Earnhardt Jr. way possible, with a nonchalant tweet on a Saturday night.

That’s how NASCAR’s most popular driver disclosed that he would donate his brain posthumously to science. His announcement came in response to a Sports Illustrated tweet and responses about three members of the Oakland Raiders deciding to donate their brains to the Concussion Legacy Foundation after learning that Hall of Famer Ken Stabler’s brain showed evidence of chronic traumatic encephalopathy at autopsy.

In fact, he wasn’t stopping with just his brain.

Earnhardt, 41, has had a number of concussions during his career. He did not disclose for five months that he had suffered a concussion in 2002 and in 2012, he had two in six weeks. Earnhardt self-diagnosed one and suffered the other in a crash at Talladega. He ended up missing two races in fall 2012.

Earnhardt, like the Raiders’ George Atkinson, George Buehler, and Art Thoms, isn’t about to retire, but the decision each of them reached, sobering for young men, shows an increasing awareness of the possible link between concussions and repetitive hits to the head to degenerative brain disease among those who participate in sports. With science only now beginning to catch up, brains are, frankly, needed for study. Presently, CTE can only be diagnosed posthumously. One issue so far has been that the most likely donors have been the families of athletes who have suspected degenerative brain disease as the cause of depression, mood swings, anger-management issues, memory loss and other symptoms of CTE.

“These are very early days, and we badly need larger studies, that include both athletes and nonathletes,” said Dennis Dickson, author of a study by a research team at a Mayo Clinic bank in Jacksonville, told the New York Times. According to the Times, the team found CTE in 21 of 66 brains of people who had played contact sports and no evidence of it in 198 people with no record of playing those sports. However, there was no way to know if there were symptoms linked to CTE because some of those people had other neurological disorders.

“This research is in its infancy,” said Robert Stern, a professor of neurology and neurosurgery at the Boston University School of Medicine “There are many outstanding questions, but we’re now working to answer them and making some progress.”

NASCAR has vastly improved safety over the years, but Hall of Famer Fred Lorenzen, whose career preceded those changes, was diagnosed with dementia and memory loss in 2009. Geoff Bodine, who won 18 races from 1979 to 2011, estimated in a 2014 interview with the Times that he had suffered at least 10 concussions.

“I pray when I wake up,” Bodine, who turns 67 next month, told the Times, “I will know who I am.”