At first, he scoffed when his wife suggested that he donate his brain for C.T.E. testing, saying “‘I’m going to donate my brain just to prove you wrong,’” Maura Horton said.

Affliction, and Opportunity

Over time, however, as more neurological functions began to fail, Horton, in quiet moments at home, accepted that he could have C.T.E. and that it might even present an opportunity.

Much is unknown about the disease, including why, for instance, some players get it and some don’t. Nearly 100 former N.F.L. players have been found to have the disease, including Hall of Famers like Ken Stabler and Junior Seau, but research on college players who did not play professionally is not extensive.

By donating his brain, Horton believed he could aid the science and, ultimately, perhaps help people evaluate whether to play, or continue playing, the game.

“He wanted to make a difference if he could,” said Maura Horton, 47. “Don would never tell someone not to play the game, because he loved football and wouldn’t betray it. But he wanted them to see a full picture to make a full decision.”

She added: “Don said, ‘If they would be more reflective and be more upfront about things that were happening to them, they might get out of the game earlier if they needed to. Kids try to hide so much about what’s really happening.’”

By 2013, Horton had left North Carolina State, but he felt the pull of the game. He became an assistant coach at a high school a few miles from his home in Raleigh. Despite his inner conflict, Maura Horton figured, the game and coaching were too ingrained for him to turn away. He did preach lessening contact at practices.