Diving Headfirst Into Football Season With A New Look At Concussion Research

18:24 minutes

two football players - one in red and one in white, both wearing helmets - colliding and falling to the ground in the middle of a game, surrounded by other players
Credit: Pixabay

Researchers have long known about the connection between concussions sustained on the football field and chronic traumatic encephalopathy, or CTE, a neurodegenerative illness caused by repeated head injuries. NFL officials have gone to great lengths to prevent concussions on the playing field, making rule adjustments and tweaks to players’ helmets.

But another group of researchers wondered—what about the hits that don’t result in a concussion? They found that even when a player didn’t show outward signs of having a concussion, their brains were showing symptoms of injury.

So what does this mean for the game of football, and the NFL’s recent drama over updated helmet technology? Brad Mahon, associate professor in the department of psychology at Carnegie Mellon University, and Adnan Hirad, MDPhD candidate in the Medical Sciences Training Program at the University of Rochester, share the results of their investigation into the unseen impacts of head injuries on football players.

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Segment Guests

Adnan Hirad

Adnan Hirad is a MDPhD candidate in the Medical Sciences Training Program at the University of Rochester in Rochester, New York.

Brad Mahon

Brad Mahon is an associate professor in the department of psychology at Carnegie Mellon University in Pittsburgh, Pennsylvania and the Scientific Director of the Program for Translational Brain Mapping at the University of Rochester, in Rochester, New York.

Segment Transcript

IRA FLATOW: This is Science Friday. I’m Ira Flatow.


Can you smell that?


Yeah. Fall is in the air. But to some people, it’s not the falling leaves or the falling temperatures, it’s the falling football players diving headfirst into the football season– well, metaphorically, at least, right? We’ve known for a while about the connection between concussions sustained on the gridiron. And Chronic Traumatic Encephalopathy or CTE. It’s a neurodegenerative illness caused by repeated head injuries.

NFL officials have made efforts to prevent concussions on the playing field, making rule adjustments, tweaks to players helmets. But a group of researchers wondered what about the hits that don’t result in a concussion? So many of them on the field, they’re just hits. They’re not concussion producing. Could players’ brains still being impacted?

Well, they found that even when a player did not show outward concussion symptoms, their brains were showing signs of injury, signs they say that could one day lead to CTE. So what does this mean for the game of football, and the NFL, and Antonio Brown’s recent drama over updated helmet technology? We asked you this week, do you think football leagues are doing enough to protect players’ brains? You sent in your answers through the new Science Friday VoxPop app. CV in Massachusetts had this to say.

CV: I think that possibly we should not have football players wear helmets. And the reason is that the helmets can only protect the skulls and can’t protect people’s brains. The brains will bounce off the inside of their skull and give them a concussion. And I think the helmets may contribute to making players feel like they are protected when they actually aren’t very protected at all.

IRA FLATOW: Mm-hmm. If you want to weigh in on that question, you can leave us a comment on the Science Friday VoxPop app and download it, or give us a call now– our number, 844-724-8255, 844-SCI-TALK. Or, of course, you can tweet us @SciFri. Now, here to share the results of their study published recently in Science Advances are my two guests. Adnan Hirad is an MD-PhD candidate in the Medical Sciences Training Program at the University Rochester. Welcome to Science Friday.

ADNAN HIRAD: Thank you for having me, Ira.

IRA FLATOW: You’re welcome. Dr. Brad Mahon is associate professor in the Department of Psychology at Carnegie Mellon University. Welcome to both of you.

BRAD MAHON: Thank you, Ira

IRA FLATOW: The caller that you just heard described the brain bouncing off the inside of the skull. Is that really what happens, Brad?

BRAD MAHON: I think the caller put her finger really on the key issue. When we look at how helmets do protect the head, it’s clear that they protect the head from catastrophic injury. They protect the skull. But as she noted, the damage that’s caused by head hits, for instance, in football is caused by rapid acceleration and deceleration of brain tissues and their contacts with the inside of the skull. And the helmet really doesn’t protect against that.

IRA FLATOW: Well, Adnan, how is the helmet then supposed to help with this?

ADNAN HIRAD: Well, it’s really important that we prevent, again like Brad was saying, contusions to the brain tissue itself. And so over the last several decades, we have made a lot of improvements on preventing skull fractures and injuries to the brain tissue itself. What it’s not doing so far is protecting the brains from the shear waves that travel throughout the brain after an impact that than cause microstructural damage to white matter tissue in the brain. Obviously, there are certain advancements that they can do in terms of padding and such, but the results of that research and those improvements are still out.

IRA FLATOW: You say there’s a shear wave. Is that like a little earthquake in your brain? Little–

ADNAN HIRAD: That’s exactly how I would describe it, little ripple effects that sort of travel across the tissue and the material properties of the different tissue types within the brain. For example, comparing the cortex to the brain stem is not the same. And so the energy waves do not travel in similar pattern across the brain because the brain is not homogeneous. And those tissue, sort of those boundary areas where the different tissue types are connecting are places where we think injury is actually occurring.

IRA FLATOW: Now, I’ve found that there is a connection between multiple concussions and CTE. But your study found that you don’t have to have a concussion to have an injury?

ADNAN HIRAD: Yes, so what we said was we were going to look for the seasonal changes to white matter structure and deficits that occur as from just playing a season of football. And we wanted to see what that would be like. What we were showing is that there is damage to white matter structure just from playing a season of football without even sustaining a concussion.

Now, what that means in terms of a recovery over time and how that results in long-term neurodegenerative process is still out. And we don’t have currently a succinct way to connect these sort of seasonal injuries to prognoses of CTE over time. And then these are studies that are ongoing that can hopefully provide some clarity to that.

IRA FLATOW: Dr. Mahon, you basically conducted these studies in what I would call teenagers, right?

BRAD MAHON: That’s right.

IRA FLATOW: Might this also be happening in Pee Wee football in even younger than teenage levels?

BRAD MAHON: I don’t think there’s any reason to believe it’s not happening in younger age groups. And I would suggest that we don’t even necessarily need to do the studies in younger age groups to conclude that it is happening. There’s no reason to believe, as Dr. Hirad was alluding to, the brain has a different elastic properties and different tissues. And a lot of the injury that we’re measuring, we think, is arising because different tissues with different elasticity absorb the forces of head hits differently.

And so those forces tend to cause injury at the junction between tissues that have different abilities to absorb those forces. And that’s going to be exactly the same in a young brain as it is in an old brain. Overall, there’s always going to be these junctions of different rigidities or elasticities in the tissue.

IRA FLATOW: How do we know that these injuries could one day lead to CTE, Adnan?

ADNAN HIRAD: So the CTE studies that have been conducted are postmortem studies, right? So players that have passed away donate their brains. And groups, including Dr. Omalu and McKee at Boston are looking at these brains after these patients die. What they find is that the [? tolopothy ?] or the or the injury and the disease process is correlated more with repetitive head hits than the concussions these players sustained throughout their lives as they played this game. Again, there’s a lot of evidence now suggesting that repetitive head trauma is more correlated again with CTE than one of concussions.

And the evidence, obviously, is observational. It’s retrospective at this point, but it’s certainly is concerning that– and now studies like ours are suggesting that there are seasonal changes from playing a season of football. So I mean we go– the question is, well, how do we go from a single season to cumulative number of seasons leading to this injury down the line? That question is still out.

IRA FLATOW: Well it’s also a question of whether there could be such a thing as a safe helmet? Is there such a thing?

ADNAN HIRAD: Certainly, the– I mean, if you just looked at the helmets that are in the market right now, and you looked at the– they have warning labels on them that basically say exactly that– there are no– these helmets cannot eliminate the risk of concussion. And the risk of concussion in the NFL has been the same over the last seven years since they’ve started producing numbers and then allowing it for the public to review. Starting from 2012 to 2018 last year, the numbers fluctuate, but they’ve stayed about the same. So we have not– if there is such a nirvana that could potentially stop concussions from occurring, we have not found it yet.

IRA FLATOW: Brad, have there been any reaction from the NFL or the football industry in general about this possibly being a paradigm shift, this discovery?

BRAD MAHON: Well, I think it’s important to recognize that in the scientific literature, there has been an emerging consensus over the past five to 10 years that there is a causal link between many subconcussive head hits and long-term changes to the brain. We haven’t had any direct response yet in the setting of our study, but I think one of the things that we were able to show is that while it has already been recognized that there’s a connection between repetitive subconcussive head hits and ultimately changes in the brain, we’re able to show a dose-dependent effect.

We’re able to show that players who had more hits of a certain type had more serious changes in their brain compared to players who had fewer hits of a certain type. And my hope is that this provides a foothold to think forward toward new technologies that would allow us to infer when injury is occurring in the brain independent and prior to players exhibiting signs and symptoms of concussion.

IRA FLATOW: Tell me about that different kinds of hits. We always see a head on head. Is that what you’re talking about? Are there two different kinds of hits?

BRAD MAHON: So when the study was designed initially in the laboratory of Dr. Jeff Bazarian, who’s an ER doc and a concussion expert at the U of R, they outfitted collegiate football players with accelerometers in their helmets. And these accelerometers, they measure not just the direction of every hit, but they also measure two aspects of its force. It’s the linear deceleration associated with the hits or the sort of inline stopping of the head, and then the rotational acceleration or the twisting of the head that’s caused by the hit.

And in some of the analysis that Dr. Hirad did for this paper, he was able to show that even if you statistically partial out the contribution of linear acceleration, so you remove the forces that are associated with inline stopping of the head, and you just look at the effect of the twisting motions, the twisting motions of the head are themselves sufficient to explain the kinds of changes that we’re seeing in players’ brains.

IRA FLATOW: So if you do away with their head butts that they’re trying to get rid of, but you still have the missed hit.

BRAD MAHON: Well, that’s right. And really every time that there is a change in acceleration. There’s a change in acceleration both in terms of the inline trajectory of the head, but also in terms of its rotational characteristics.

IRA FLATOW: All right, got you. We’re going to have to take a break. I want to thank Dr. Brad Mahon, an associate professor in the Department of Psychology at Carnegie Mellon University. Dr. Hirad is going to stay with us. When we come back, we’re going to talk about what the NFL is doing or not doing to prevent concussions on the field. Our number, 844-724-8255. Stay with us. We’ll be right back after this break.

This is Science Friday. I’m Ira Flatow. We’re talking this hour about new concussion research and what it means for the safety of football helmets. And we’ve been taking your comments on football and concussions via our new Science Friday VoxPop app, which lets you easily share your voice comments with us. And here’s a comment from Michael in Knoxville, what he had to say.

MICHAEL: In football, there’s a dangerous conflict of interest between the teams who take responsibility for the well-being of their players and also need those players on the field to win the games. Until the league itself takes over, the responsibility for the players’ well-being and makes the decision whether or not a player can play after an injury, we will always have this problem of teams putting players back on the field when they shouldn’t be.

IRA FLATOW: Let us know what you think, besides Michael from Knoxville. You can all download our Science Friday VoxPox app and let us know. And here to continue talking with us about this is our guest Dr. Adnan Hirad, an MD-PhD candidate in Medical Sciences Training Program, University of Rochester. Let me talk about this discovery, about the two different ways of twisting in your brain. The league has made changes to try and prevent concussions from happening, but that’s all focused on the linear acceleration. And the research we’re talking about says it’s not the linear acceleration that the real culprit, it’s the turning of the head.

ADNAN HIRAD: Certainly, it’s true. And more importantly, a little bit of history on helmet safety rankings that the NFL is using to bar Antonio Brown from using his previous helmet is actually important to sort of go through. So around 2010, 2011, the NFL started testing helmets that the manufacturers were making available to the players. And the conditions they used were similar to conditions from games. They took dummies and retrofitted them with these helmets.

And what they found was that the testing conditions that were resulting in a lot of concussions were helmet-to-helmet sort of scenarios. And so to their credit, the NFL made that particular sort of hit illegal. What we– what’s not public knowledge at this point is the fact that 70% of concussions that are occurring in these seasons are due to scenarios that have not been tested in the lab. These are helmet-to-grand impacts. They are helmeted heads against the bodies of the other player.

And so these conditions have now been tested. And so it’s like me you know telling you, Ira, that your car manufacturer telling you, we’ve tested your brakes, but it’s only on 30% of possible driving conditions. And the rest of– 70% of the driving conditions that you will experience, we just don’t know how your breaks are going to function. I don’t know if you would buy that particular car. I certainly wouldn’t.

IRA FLATOW: A couple of quick phone calls we can get to. Let’s go to Patrick in San Francisco. Hi, Patrick.

PATRICK: Hey, how are you?

IRA FLATOW: Hi there, go ahead.

PATRICK: Yeah, just a quick observation. So the game of rugby doesn’t have helmets. And its general consensus is that this disease is dramatically less pervasive in that space. And it’s obviously a very similar game, very aggressive, physical contact, and tackling. And also just referencing the comment about helmets essentially not preventing brain damage or brain impact, but definitely masking the body sensation of impact, which, if anything, protects the skin and protects the bone, but masks repetitive damage to the brain. I’m of the opinion, if anything, removing helmets completely is potentially the simplest solution, a slight modification to the game, the removal of helmets–


IRA FLATOW: Let me get a– let me get– let me get a reaction to that. What do you think, Dr. Hirad?

ADNAN HIRAD: Well, I really can’t talk to the effects. Removing the helmets completely, again I’m for evidence-based changes. At this point, I’m not sure of that is going to resolve the problems we’re having. But certainly improving the helmets themselves, at least to make sure that they address these other impacts scenarios that are known to result in concussion, again 70% of concussions that I’m talking about from NFL games from 2015 to 2017.

So improving the helmets so that they can at least address some of these impacts and these other scenarios is going to be really important. And so right now the NFL is not setting the standards for what is needed for player safety. Manufacturers are producing these helmets. And then the NFL is just ranking them as they come. There are no thresholds that they set themselves.

IRA FLATOW: Is it possible that other sports where heads are getting knocked like, martial arts, boxing, that sort of stuff have the same kind of thing going on?

ADNAN HIRAD: Oh, yeah, I mean, in boxing, we’ve known it for a long time that they result in a condition very similar to CTE because of these repetitive head blows. And the number of years, for example, a player had played was sort of correlated with the occurrence of what they call dementia pugilistica. And so it’s been known in that. Now, UFC and other types of games are younger, so we don’t know what the results of that are going to be.

IRA FLATOW: Well, it’s quite interesting. We run out of time. I’d like to thank you for taking time to be with us today.

ADNAN HIRAD: Well, thanks so much for having me.

IRA FLATOW: Dr. Adnan Hirad, an MD-PhD candidate in the Medical Sciences Training Program at the University of Rochester.

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