The following script is from "Football and the Brain" which aired on Nov. 15, 2015. Steve Kroft is the correspondent. Draggan Mihailovich, producer.
If you are one of the millions of people who watched football before this broadcast -- many of you on this network -- you know that NFL players get their brains rattled on a weekly basis and for some of them the long-term consequences may eventually offset the glory of playing the game. After a decade of denying a link between onfield concussions and brain impairment later in life, the NFL finally acknowledged the connection and is now trying to reengineer the sport to fit the medical science. It's changing the rules, trying to reinvent equipment and funding scientific research that might endanger its future both as the country's most popular sport and as a multibillion-dollar industry. Not since football was nearly banned a hundred years ago has the sport been under the microscope the way it is today and all of it has to do with matters of the brain.
Just minutes into the very first Sunday of this NFL season, Cleveland Browns' quarterback Josh McCown knocked heads at the goal line. It was the kind of violent hit that millions tune in every week to see. In years past, McCown might have stayed in the game. But after he failed a concussion assessment, he was taken off the field, and not allowed to return to action for two weeks. These days if a concussion is even suspected, players are removed from the game, even if they don't like it.
It's just one of 39 changes that have been made to make the game safer. Helmet-to-helmet hits are now illegal. The kickoff, one of the most dangerous plays in football, has been moved up to discourage returns and high-speed collisions and independent neurologists are not only stationed on both sidelines to look for signs of brain trauma, there are now athletic trainers high above every stadium with the authority for the first time to stop the game if they believe an injury has gone undetected.
"I do believe it's safer. But injuries are part of active sports and they're certainly part of football. Football is a contact sport."
["Ooh. Tag it. He got up but he got drilled."]
All of this has happened under the watch of NFL Commissioner Roger Goodell who told us that concussions are down 35 percent since 2012.
Steve Kroft: You think the game is safer than it's ever been before?
Roger Goodell: I do. I'm convinced of it. I think the changes that we've made have had real results. And we're seeing that.
Steve Kroft: But do you believe it's safe?
Roger Goodell: I do believe it's safer. But injuries are part of active sports and they're certainly part of football. Football is a contact sport.
Despite the changes and the reduction of concussions, there are still a lot of them. On the average, a half-a-dozen a week, according to the NFL's own figures.
Steve Kroft: Can you take the violence out of football?
Ed Reed: No.
Ed Reed retired earlier this year after 12 seasons as one of the NFL's all-time great safeties. During his career, he dished out as many hits as he took.
Ed Reed: Football is a reaction sport.
Steve Kroft: You can't choreograph it.
Ed Reed: You can't. It's not a movie. We always said it's not suit-and-tie on the football field.
Steve Kroft: How many concussions do you think you've had?
Ed Reed: That I remember? I'd say three or four.
Steve Kroft: You think about the future. Do you worry about the fact that you've banged your head and had a lot of high speed collisions.
Ed Reed: Yeah, I am worried about it. I think about it because something could come out of me have been running into people all my life.
What worries Reed and the NFL and what's behind all of these changes is something called chronic traumatic encephalopathy or CTE, a degenerative brain disease that was primarily associated with boxers until 13 years ago. That's when a neuropathlogist in Pittsburgh, Dr. Bennet Omalu, found it in the brain of Steelers Hall of Fame center Mike Webster during an autopsy. CTE can only be diagnosed in the dead. The late Hall of Fame tight end John Mackey had it and so did 87 other former NFL players with serious symptoms whose families donated their brains to an ongoing study being conducted at Boston University.
Steve Kroft: Do we really know that playing football causes CTE?
Dr. Robert Stern: Do we really know that smoking causes cancer?
Dr. Robert Stern, who directs the clinical research for Boston University's CTE Center, says the science is still in its infancy but the evidence indicates a strong connection.
Dr. Robert Stern: We know from all the neuropathologically confirmed cases of CTE that every case has had one thing in common, a history of repetitive head impacts. That means that...
Steve Kroft: It's not good for you.
Dr. Robert Stern: It's not good for you. It's a necessary variable to get this disease. But just because you hit your head a bunch, doesn't mean you'll get the disease. So we have to figure out why one person gets it and another person doesn't.
To be clear most NFL players don't. Stern says the number of confirmed cases is still small. Thousands of former NFL players seem to be unaffected.
Dr. Kevin Guskiewicz: One of the challenges, Steve, is that concussions are sort of like snowflakes, there are no two alike.
And none of them good according to Dr. Kevin Guskiewicz who has been researching the link between football and brain trauma at the University of North Carolina for more than a decade. His studies indicate that players are five times more susceptible to dementia later in life if they've sustained three or more concussions. He and his team have examined 650 former NFL players.
Dr. Kevin Guskiewicz: Four out of every five that come through our door look pretty good. It's, it's sort of what is it that creates this perfect storm that puts somebody on that slippery slope at a younger age toward developing this neurodegenerative disease.
And there's no consensus. Dr. Stern at Boston University isn't convinced there is a direct link between concussions and CTE. He thinks it may be tied to the accumulation of thousands of lesser subconcussive hits -- the kind that linemen absorb on every play.
Dr. Robert Stern: We're talking about the overall exposure to repetitive head impacts, not a single injury, not a single concussion.
Steve Kroft: That's an occupational hazard...
Dr. Robert Stern: That's an occupational hazard. That's part of playing the game of football.
To reduce the amount of head banging, the NFL and the Players Association have limited the number of full contact practices during training camp and the regular season. And the league is spending millions to try and soften the blows...
In Seattle, the University of Washington and a company called Vicis are developing and testing a new kind of helmet with seed money from the NFL. The materials and technology are so secret Vicis wrapped the outer shell so competitors wouldn't get a peek at it. They're hoping to reduce concussions by 50 percent. Jeff Miller is the NFL's senior vice president for health and safety.
Jeff Miller: I'm not gonna suggest that there's any one idea that's a silver bullet. I think that we're going to be able to, over time, disrupt the helmet industry.
Steve Kroft: What do you mean disruptive?
Jeff Miller: Helmets are fantastic at doing what they were intended to do, which is prevent skull fracture. But to be designed against concussive injury is a much bigger challenge. But to the extent that the NFL can encourage other inventors, two guys in a garage somewhere, to come up with a better helmet, then we're taking that on as our responsibility to do so.
The NFL is also providing money to develop materials to put underneath the turf to cushion impacts. The league estimates that seven percent of all concussions are caused by heads slamming into the turf. That's what happened with Kansas City's Jeremy Maclin in October.
The NFL has sent one of its biggest checks -- $30 million -- to the National Institutes of Health for research primarily focused on the brain. Six million of that is going to Boston University, which has produced some of the most damaging evidence linking football to brain injuries and is trying to determine how widespread CTE is.
Steve Kroft: Are you concerned about what they may find? Are you worried that...
Roger Goodell: No, we don't Steve...
Steve Kroft:...that you're sowing the seeds of your own destruction?
Roger Goodell: No. We want the facts. We think the facts will help us develop better solutions. And that's why we're advancing medical research. That's why we're funding directly to Boston University on some of this research.
The big breakthrough will come if and when a test is developed to diagnose CTE in the living.
Dr. Robert Stern: That's the focus of pretty much every day of my life.
Steve Kroft: How close are you?
Dr. Robert Stern: I am pretty confident that we're gonna be able to diagnose people while they're alive pretty accurately, somewhere in five to 10 years.
If it happens there will finally be answers to a lot of questions but some tricky new ones will also be raised. Who would have access to the information and how would it be used?
Steve Kroft: If they'd had a test when you were playing, would you have wanted to take that test?
Ed Reed: If they're going to give me this test and this test is going to be a negative towards me as a player and I gotta go home now and I can't play this game anymore, no. I don't wanna know till after. I don't wanna know until when I'm retired. No guy would want that. No player would want it.
There has already been one controversy over another test that involves putting sensors in football helmets.
[Dr. Kevin Guskiewicz: These are the six single-axis accelerometers...]
Kevin Guskiewicz and his staff at North Carolina have been using the Tar Heel football team as lab rats to collect data, measuring the frequency and the force of every hit to the head.
["This is one impact? This is one impact"]
Guskiewicz used information from the sensors to help persuade the NFL to move its kickoff in 2011. But keeping track of the number of hits has become a political football. The NFL outfitted two of its teams with the sensors for half a season in 2013, then pulled the plug. We asked the NFL's Jeff Miller why...
Jeff Miller: The results were not what we were hoping they would be. And the Players Association, in large part, wanted to discontinue the testing. And we, we respect that decision.
Steve Kroft: What do you mean not what you were hoping for?
Jeff Miller: We were, we were, we were hoping for more, for, for more accurate analysis. It just wasn't, yet.
Dr. Kevin Guskiewicz:: Yeah. Well, I sit on their committee and I'm able to tell them I disagree.
If you want a sense of how much contact we're talking about, a study using helmet sensors on the high-school level showed that players can average 650 hits to the head per season.
Steve Kroft: That seems like a lot of head banging.
Roger Goodell: Well, that's why we're making the changes. And those changes are going all the way through to high school and youth football. Which is, "You don't need to train the way you trained before. You don't need to teach the way you taught before."
Seattle Seahawks coach Pete Carroll is tinkering with the very essence of the sport: tackling.
[" Hi, this is Coach Pete Carroll of the Seattle Seahawks."]
He's teaching the virtues of what he calls Hawk tackling where players use their shoulders and not their heads to bring down an opponent rugby-style. Carroll knows it won't work on every play. Football is too fast. He was one of the people who initially argued against changing the game.
Steve Kroft: You were late to this party in a way, weren't you? I mean, in terms of the new rules and safety rules.
Pete Carroll: Well, yeah, because I, I was an old-school guy. I was fighting for the way the game had always been played. And the first thing that hit when you're trying to make a play is your head. The whole thing about concussions has brought to light a total new awareness. And outta that a new awareness has brought adaptation. And you either evolve with it or you're, or you're, we're gonna mess it up.
Carroll is still concerned about the future of the sport and worries that mothers may stop allowing their kids to play tackle football. But Ed Reed has no regrets about the life he chose.
Ed Reed: Now that I know the dangers? Yes, I still would do it again. Why? 'Cause look at me. Look at my family. They're able to eat, they're able to have food and shelter over their head. Would I play football again? Yes.
Steve Kroft: We've talked to a lot of people. They seem to be worried about the survival of the game.
Ed Reed: You hearing people saying the game is gonna, I don't see football going nowhere. It's evolving. It's not going anywhere. Shhh, calm down.
Steve Kroft: You're not worried about it?
Ed Reed: No way! Football is not going anywhere.
"Yes, I still would do it again. Why? 'Cause look at me. Look at my family. They're able to eat, they're able to have food and shelter over their head. Would I play football again? Yes."
The game has been in this place before. In 1905 President Teddy Roosevelt had to intervene to save football after 19 deaths on the field led to calls to ban the sport. As a result, the forward pass was introduced to reduce impacts and later the leather helmet. Until now, the game has always been able to adapt...
Steve Kroft: You think the game will survive on its own?
Roger Goodell: I think the game will survive because we will continually seek to find the facts and adjust when we see those opportunities to make our game safer. And I think people want to see the game safer. We certainly want to see the game safer and we want those facts more than anyone.