By Julie Parise, CBSNewYork.com
But you can't tell by looking at him.
The former Giants great walked the red carpet at a recent event in New York City's iconic Waldorf=Astoria hotel, simultaneously chatting up fellow superstar athletes, granting interviews to the zealous media and signing autographs for eager fans.
Carson was diagnosed with post-concussion syndrome in 1990, two years after he retired from the NFL. Before his 13-year career with the New York Giants, he only thought he understood the dangers of entering into a sport which, by sheer virtue of its rules, encourages head-on collisions.
"When I played, nobody really knew the residual effects of concussions and what it could lead to – dementia, Alzheimers and ALS – so we were, in my era, in my generation, basically flying in the dark," Carson said.
HEAR MORE: Carson Tells CBSNewYork He Never Would've Played Football
Had he foreseen the tragic effects of the game on the human brain - and the subsequent suicides of players like Ray Easterling, Dave Duerson and Junior Seau - the football star said he never would've played.
"From a physical risk standpoint, I knew that you could get hurt physically and I assumed that risk," the Super Bowl champion said. "But from a neurological risk standpoint, I didn't know. So knowing what I know now, I would never have played football."
Carson is joined by fellow NFL legends like Terry Bradshaw and Joe DeLamielleure in saying he would warn others, including his own grandson, not to play football.
"Now if people wanted to play, they're taking their livelihood and they're taking their health into their own hands, and it's a tradeoff," he said. "They're leasing their bodies out for the game."
And when that lease is up, outer wear and tear on the body will likely mend. Carson is living proof, however, that damage done to the brain may not.
"Physically I feel pretty good," he said. "But you know there are days when I have not so good days, when I have headaches and blurred vision and all that stuff, so it's something that I've learned to live with. I live a pretty normal life."
Given his famed tenure in the NFL, one may assume the legendary linebacker would be quick to dispute the idea that he regrets his time spent as a pro football player.
But with the question posed, a reflective Carson paused to think before answering.
"You know what? It was a learning experience for me," Carson said. "Regret? I'm not going to say regret. But if I had to do it all over again, I would not have played."
"I never would've put my brain at risk. My body? Yeah. But my brain, that's a different story," he said. "Because that whole brain thing lasts forever."
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