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Episode 19: Concussions, TBI, and Sports
13 Plays5 years ago
Evidence has mounted that high-impact sports like boxing and football can lead to later cognitive problems, and there is increasing awareness that concussions should be taken seriously. So how does this all happen, and should you be worried? We take a look at some recent studies that shed some light on the topic.
Articles:
https://jamanetwork.com/journals/jama/article-abstract/2645104
https://www.sciencedirect.com/science/article/pii/S104474311500041X
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Transcript
Introduction and Episode Focus
00:00:08
Speaker
Welcome to Cog Nation. I'm Joe Hardy. And I'm Ralph Nelson.
Concussions in Sports Overview
00:00:13
Speaker
On this week's episode, we're going to be talking about concussions and sports.
00:00:18
Speaker
the impact of sports like football or boxing. Some people would even say soccer where you might have people butting heads and potentially having a concussion and how that can, the effects of that might accumulate over time and cause some potentially very serious problems with your brain. Specifically, we're going to be talking about chronic traumatic encephalopathy or CTE as well as some of the more minor effects of concussions.
00:00:47
Speaker
So I think it's been kind of a hot topic recently, or at least in the past few years when people are thinking about what the results of playing high-impact sports are.
The Worth of Playing High School Football
00:00:59
Speaker
So is it worth it to play football in high school if it could potentially lead to cognitive debilitation so that you have difficulty in performance later on?
00:01:11
Speaker
and what the results of playing football for an entire career, say in the NFL, what that does to your brain. I think we've come a long way in understanding how concussions work, what the shorter term effects and the longer term effects are.
New Rules for Athlete Safety
00:01:27
Speaker
That's right. And in the state of California recently, there's been some legislation
00:01:34
Speaker
in and around the amount of time that high school athletes can spend in full contact football, for example. So they're limiting the amount of time that people can do full contact in practice. So really trying to just reduce the amount of total exposure to potential head injuries in football. So it kind of raises the question or begs the question,
00:02:02
Speaker
this is really so bad that you wanna limit the amount of times that you're banging your head into somebody. Should you be doing this at all? And is there a safe amount of football to play, for example, or a safe amount of boxing to do? Or particular precautions that you might take that could make sure that you're less likely to sustain any of these kinds of injuries. That's right, exactly.
Understanding Concussions
00:02:25
Speaker
I think maybe to start off with, it might make sense to talk a little bit about what a concussion is and how it happens.
00:02:30
Speaker
And then we can talk a little bit about some of the history and background of what we know about the long-term effects of concussion. So what is it that a concussion does in the first place? So a little terminology. So we tend to call any kind of
00:02:50
Speaker
at least mild kind of injury from a concussion or from some head insult, traumatic brain injury or TBI. So we might refer to things as TBI in this episode. And the kind of TBI that people might be familiar with is just bonking your head against something. Then it results in just kind of uncomfortable sensations afterwards. So some dizziness, maybe some nausea,
00:03:19
Speaker
difficulty in concentrating, even some amnesia around the event and headache is extremely common. These, a standard kind of concussion like this, which would be a mild kind of TBI, is something that would be resolved within
00:03:36
Speaker
generally resolved within a few weeks and then you can get back to normal functioning. So that's in terms of actual functional differences. There are indications from neuroimaging that it could take, usually there are some problems that hang around maybe for a month or more to get to normal. So even though you're functioning perfectly normal, your brain still takes a little longer to fully prepare and get ready for functioning.
00:04:05
Speaker
In terms of the physics of what's happening here, I think the big issue in concussion is the issue of acceleration. If you are running at somebody, and you've got your head down, and they've got their head down, and both of your heads slam together, the helmet's slammed together, if you're running really fast and the other person's running really fast, then you suddenly come to a stop.
00:04:32
Speaker
This is a very quick deceleration. So in other words, there is a tremendous force that's applied to your head at that moment. And what ends up happening is
00:04:46
Speaker
the inside of your head, the brain, doesn't slow down as fast as the outside of your head, your skull. So the soft tissue in your brain slams against the front of your skull. That's called the coup. And then oftentimes it rebounds and slams back into the back of your skull. That's called the counter coup.
00:05:10
Speaker
Yeah, that's right. And so if you get that kind of injury where you're in maybe something like in a car accident where you're sort of jostled forward and then backwards, that would be exactly that coup and counter coup kind of situation. And the result of this is that you get
Mechanics of Brain Injuries
00:05:29
Speaker
sort of focal or the most injury in the place where you come in contact with something or where your head is going forward and then as your head snaps back in the other direction you get the second most damage on the other side of your head so you can get some sort of physical smooshing of your head through this this hitting you know your your squishy brain hitting against
00:05:51
Speaker
So this is something that kind of reminded me of an earlier episode that we had on the Frey effect. And if you remember, the Frey effect was hearing sounds from microwave radiation. So microwave radiation
00:06:07
Speaker
pulsed microwave radiation kind of jiggles the brain a little bit and that frequency that it jiggles at can go over to the auditory system and you can actually hear a sound. Now thinking about the brain this way, you've got this soft jiggly tissue that's surrounded by
00:06:29
Speaker
a bunch of cerebrospinal fluid and this is built to protect the brain as much as possible so you know minor jolts back and forth shouldn't do damage to the brain but if you hit it hard enough you know this really soft tissue can't be protected anymore so you're sort of reaching the limits of how much your
00:06:48
Speaker
cerebrospinal fluid in your skull can help. The other result of this, so besides causing damage to the place where it's hit and the opposite side of the head, you also get stretching in the brain. So since it is this soft tissue, as it, you know, accelerates at a different rate, as you said, Joe, than the skull, because the skull is stopped immediately and
00:07:11
Speaker
say the brain is still moving forward, this causes some stretching out of the soft tissue and a direct result. Well, there are a whole bunch of direct results of that, but that's one of the basic disturbances that's being caused by a concussion.
00:07:26
Speaker
And this kind of stretching of the connective tissue within the brain, the exact model of how this works is not fully worked out from a physiological standpoint. But the current model really is that you have axons, which are the long bits of neurons that connect between different locations within the brain.
00:07:45
Speaker
and sends signals across from one neuron to another neuron. These axons are the parts that are getting really stretched out, and this is causing some direct damage to the axons themselves and the neurons themselves, but it's also potentially causing inflammation and some secondary kinds of effects down the road.
00:08:08
Speaker
And this will be localized in a particular area, but it can also be quite general because the entire brain is being distorted in its shape and stretch. And as we're learning more about the processes of exactly how this happens, you've got this finely tuned organ, the brain, that's got all these neurotransmitters moving around in it. And all of these connections, if you stretch it out, you're just
00:08:35
Speaker
you'll just upset the equilibrium here. So one of the immediate results is that you get a cascade of neurotransmitters, so these chemicals in the brain,
00:08:48
Speaker
just kind of going out of whack. And one result is that you change calcium concentrations in the brain, which causes this whole chain reaction that can cause degradation to the cell walls and can also cause irreversible damage to axons in the brain. So there's essentially a chemical imbalance that's causing some, you know, because of this physical damage,
00:09:15
Speaker
It's disrupting the chemical concentrations in different parts of your brain. Some of this is what causes over-excitability of some neurons and then depletion of some of these energy sources and irreparable damage to certain axons. The more the damage there is, the more you're going to disrupt this whole system. I was thinking going over some of these materials preparing for the pod, why is this a topic now?
00:09:43
Speaker
humans have had heads forever throughout our evolution. It seems to be increasingly a topic of conversation. I think there's some very real reasons why that is. What is it? The kind of accelerations that we're experiencing, whether we're driving in a car or we're slamming into each other with football helmets on, are not
00:10:09
Speaker
evolutionarily typical accelerations in evolution prior to the advent of motors and engines. You wouldn't really get the kinds of speeds typically that you get in a car unless you're falling out of a tree. Yeah. And the kinds of decelerations that you get when cars impact one another are really dramatic beyond what you would normally experience any, in any other situation, you know, in evolutionary history.
00:10:36
Speaker
And then in the case of football, one of the reasons why football is so dramatic, even though people have been butting heads for forever, is that repetitive in a way that is enabled by the helmet itself. So because it hurts much less to bang your head into someone else, when you're wearing a helmet, you are
00:10:57
Speaker
You do it more often, you're willing to do it more often. And it doesn't seem like it's as damaging when you're doing it. So when you have the safety gear, you actually can be doing more damage because you're under the assumption that you can go with whatever force you want. Exactly. And the problem is that the outside of the brain has pain receptors, I'm sorry, the outside of the skull, the head, the surface of the skull, the scalp, and that area has pain receptors.
00:11:28
Speaker
the brain does not. So the brain itself does not have receptors for pain. So you wouldn't feel the damage directly to your brain, but you would to the outside of your scalp. So when you hit your head against something, what you're really mostly feeling is that pain from your skin and from the soft tissue on the outside of your head.
00:11:50
Speaker
I wonder if it has something to do with the somewhat nonspecific symptoms that accompany a concussion to that sort of dizziness and difficulty concentrating. If that's something that, you know,
00:12:04
Speaker
It doesn't sound as real as an open wound that's clearly damaged, that maybe they're just slacking off or it's not a real injury. That's right. Yeah.
CTE and Athlete Health
00:12:17
Speaker
And I think one of the things that's come up recently is
00:12:22
Speaker
you know, some very high profile cases where former athletes have committed suicide because they had what they attributed as symptoms related to brain injuries they experienced playing football. For example, Junior Seau, former football player who committed suicide after a long career of
00:12:46
Speaker
very successfully playing football. And he really explicitly attributed the problems that he was having to these kinds of symptoms related to the injuries he received playing football. Yeah, and it's somewhat I think it's somewhat unclear exactly what the link between concussion and depression is. But in the paper that we look at, I know that a significant amount of the of the
00:13:13
Speaker
football players who had died and donated their brains had succumbed to suicide. So you've got very severe depressions that are somewhat controversially linked to these injuries that occur during the sport playing football. You've also got more cognitive type symptoms, especially as players get older. So the hypothesis is there are these effects of
00:13:41
Speaker
brain injury that are cumulative over time that actually increase with age. So even after you stop playing, the impact of the previous injuries is somehow accumulating. And this is interesting. I think your comment about the fact that we wouldn't normally go out and seek getting our head hit against hard objects prior to some organized sports, right? I can't think of.
00:14:09
Speaker
when people would have engaged in a profession where you repeatedly just bashing your head over time. It might happen every once in a while, but as a real accident and sort of an outlier event. But professional football players are getting this day in and day out for years and years. And boxers as well. Oh, especially boxers, sure.
00:14:34
Speaker
Yeah, I mean, I think historically, boxing is the place where you probably saw this the most. You know, of course, in boxing, you've got the idea of a knockout, which is, you know, very explicitly, you know, causing someone a concussion that that results in unconsciousness. Oh, yeah, even forget the knockout. You're just you're just in a ring trying to beat on each other's heads. Right, exactly. So the idea of like punch drunk syndrome, you know, that over time,
00:15:02
Speaker
you know, as you get as the boxer gets older, you know, they have problems cognitively and potentially physically as well, due to the to the brain injuries they sustained. So that's the old terminology, or at least what they would use for boxers, maybe a century or so ago, punch drunk syndrome, even more nonspecific than TBI, but but that would be terminology that would have been used.
00:15:28
Speaker
probably the best known example of this, uh, was Muhammad Ali. Uh, someone who had, you know, pretty significant problems, uh, both cognitively and physically after his career as a boxer, it's difficult to attribute in a, in a single case to say that that is due to the injuries he sustained as a boxer. But many people believe that that's the case.
00:15:53
Speaker
Now, I think he had Parkinson's too, which makes it a little more tricky to figure out exactly.
00:15:59
Speaker
It's complicated, yeah. And some are even attributing things like dementia. In Parkinson's, people might say that you actually are more likely to suffer from those diseases if you sustained traumatic brain injuries earlier in your life. When you're looking at sort of a micro level in the brain, you're seeing some similarities between Alzheimer's disease and severe concussions. You're seeing
00:16:25
Speaker
what are called neurofibrillary tangles. So tangles in the actual cells that are causing damage in both Alzheimer's and in concussions. So it's unclear exactly how causality works there. Right, exactly. You've got these what are called tau tangles that are
00:16:46
Speaker
showing up in both scenarios. Hyperphosphorylation of tau is one of the main markers that is seen in chronic traumatic encephalopathy, which is that condition that is related to
00:17:02
Speaker
having been exposed to a lot of concussions earlier in life. I found particularly interesting the list of the most dangerous sports that are out there. And I think this would probably be of interest to most people. So, okay, so the top 20 sports and recreational activities with the highest risk of head injuries.
High-Risk Sports for Head Injuries
00:17:20
Speaker
So number one is cycling. That makes some kind of sense, right? Especially if you don't have a helmet on. Well, even if you do have a helmet on, to the point we were making earlier,
00:17:30
Speaker
If you knock your head against the pavement, you're going to have massive deceleration in your brain. Your skull might not break, which would be an advantage. Certainly good to wear a helmet for that perspective.
00:17:47
Speaker
But still, that concussion could be serious. Second is football. That makes sense. And that's kind of what we're basing our discussion around today. And then baseball and softball. And I think that's mostly because of being hit by a pitch in the head. There's the risk of being hit by a pitch in the head. So they specify that it's when hitting, when batting. Basketball.
00:18:11
Speaker
soccer to some extent. And you can see that there's been some studies on effects of heading the ball. So if you're, you know, if you're repeatedly hitting the ball hard enough with your head, that could accumulate into something. And then, you know, golf is kind of way down at the end, I guess you. That would be tough. Horseback riding, horseback riding, hockey, of course. Yeah, but yeah, golf. Where is where is hockey relative to golf?
00:18:41
Speaker
Well, hockey is actually less risk of head injuries. But I think that may be because just the pure number of people that are playing golf. So they're just talking about number of people going to the emergency room. Oh, OK. So it's not it's not like on like a on a per hour. It's not I think it's not on a per hour. It's not on a per hour basis. So and you can I mean, you can see that's why cycling would be first, because it's such a popular sport. And so many people cycle.
00:19:12
Speaker
Certainly fewer people play football. No, but hockey's got to be. If you're playing hockey, that's definitely more dangerous than than golf. That's probably more dangerous than baseball as well. I mean, in baseball, where you see this a lot is actually with catchers because catchers get foul balls off their face masks all the time, especially at higher levels. Professional baseball, I see this all the time. Once every other game, probably.
00:19:38
Speaker
a catcher will catch a foul tip off their face mask. And that's a pretty significant impact. And umpire is good as well. And again, cumulative too. Yes. Trampolines on there. I don't know. There's trampoline parks are becoming more popular now. Yeah. People have trampolines in their backyards. You come down on the edge of that, the side of your head, or you just fall off it and land it on the ground.
00:20:04
Speaker
So I think the clear message from all this is if you want to avoid head injuries, just do any sports. Stay inside. But I guess apart from that, because that's not really what people want to hear. We're not trying to encourage that. That's not what we're going for. You should live an active life. But maybe bearing in mind some of the activities that could be more likely to give you a head injury and think about how you might mediate that a little bit.
00:20:33
Speaker
There are some interesting examples in there. Soccer is an interesting one because people talk a lot about that from the perspective of headers. So heading the actual ball. One of the papers we were reading was indicating some research that in controlled studies, they didn't see immediate impacts on the brain of heading in a controlled environment. So hitting one time. Yeah, even multiple times.
00:21:01
Speaker
If you're just doing that in isolation by yourself, so that the speculation was that maybe in soccer, what's causing a lot more of the, uh, concussions is when you go, say, for example, when you go to head, oftentimes two players will go at the same time for the ball and they'll crack skulls. Uh-huh. And that definitely is, you know, is an impact. Oh, and certainly in baseball too, I guess.
00:21:29
Speaker
you know, when you're trying to catch a ball at the same time. At least that's what makes it under the highlight clips. Yes, exactly. But yeah, I mean, I think, you know, I think there are some sports where it's sort of, if you take mixed martial arts and boxing, those sports are clearly not a good idea from a brain injury perspective. You should not do those. Probably never. Ever. You should never do that. If you care about your brain, if you plan on using your brain in the future,
00:21:59
Speaker
you should not do boxing, period. It's dangerous. It's extremely dangerous. You're trying to knock the other person out. And what we're saying is that getting knocked out is a serious thing. It's not like a minor detail in your life. It's a significant entry that needs to be taken very seriously, especially if you're planning on having that happen multiple times over time. You should probably try to avoid that. So I feel like if you look at the spectrum of things,
00:22:28
Speaker
I feel like boxing is way out on the far end of like, just don't do that. That's not a good idea. People want to do it. That's up to them. But from a recommendation standpoint, it's pretty clear. I think what you need is those giant boxing gloves and then those huge balloons that you sit in. That's right. So you can't actually hurt each other. Right, exactly.
00:22:51
Speaker
Maybe
Weighing Football's Risks and Benefits
00:22:52
Speaker
that's the next step. That's the next, that's the next level, but you know, I then, then there are sports where you're like, well, it could definitely happen. And I feel like that's where you take like baseball and soccer. We were like, yes, there is a significant risk of having a head injury.
00:23:08
Speaker
While you're playing the sport at the same time is the positive impact of playing the sport outweighing that some good arguments to be made for for sports like that and then yeah then you've got something like i don't wanna get into cycling cuz that's like a that's a totally different. Problem because it gets into the whole thing of like.
00:23:27
Speaker
traffic rules. And I mean, that's a whole different to me, that's like a different topic in a way. Right. The kinds of people who are ending up in the hospital for that oftentimes are just people commuting or, you know, riding on the streets, etc. That's like a whole different topic. So cycling is dangerous, right? There's no question, not just for your head in general, it's dangerous, but also very healthy for you in other ways. So again, that's like, that's another, another issue.
00:23:52
Speaker
I think there's certainly a difference between cycling and boxing in that you can try to be more situationally aware in cycling or you can sort of improve your expertise or try to aim for a little more safety while you're doing it. Whereas boxing, there's no getting around the fact that you're just going to be hit in the head a whole bunch of times. It's also the point of boxing, right? I mean, the point of cycling is not scraping your head against the ground.
00:24:17
Speaker
That's right. And I think about something like basketball. So that's the fourth highest risk sport with head injuries. You're not going to wear football helmets while playing basketball or wear equipment like that. But maybe there's some room for referee calls and trying to keep the game cleaner so that it doesn't happen as often because seeing that it is a genuine risk and it is actually hurting people. Right, exactly.
00:24:44
Speaker
Exactly. So I think if you put those on two different ends of the spectrum, if you take some of these lower impact sports on one end of the spectrum and boxing on the other end of the spectrum, the interesting area is football because football is a thing where I am of the opinion that you should not play football and you should not let your children play football. No, did you ever play football? I did.
00:25:10
Speaker
I did. So when did you when did you play? I wasn't very good at it. So fortunately, I didn't play very much. Yeah, I was to say I was lucky in that I was not good at it either. Yeah, when did when did you stop? I stopped in. I started and stopped in eighth grade, right? So I went through one season, I had to follow through, I had to do it. Luckily, the
00:25:32
Speaker
coach was watching out for me and didn't put me in the game a whole lot. So I don't think I have too many resultant, too much resultant brain damage, but yeah, I was, I was not particularly suited for football at that age. I played flag football. So I'm trying to remember what grades those were. I think it was like a fifth or seventh grade, something like that. Uh, so it wasn't tackled for no helmets. It was helmets. It was helmets. It was helmets. Yeah. Um, but you didn't tackle, you just try to grab a flag, but I played
00:26:01
Speaker
I was a line, like offensive lineman and defensive lineman. There was a lot of impact there as you're just bumping into each other, as well as in practice. I think I actually got knocked out once in practice. I think that was the one time I got knocked out. Oh, you actually got knocked out. Yeah. Yeah. I remember it was Dan O'Connor, my friend, and I squared up in one of these tackle drills or like blocking drills, maybe it was. He just, yeah, the kid was fast and strong and he just knocked me out.
00:26:32
Speaker
Dan, if you're listening. It's all good, Dan. Tweet your apologies to Joe. It's all good. But he forgives you. He was just playing the game and doing it much better than I was. In terms of that, I mentioned at the beginning of the top of the show, in California,
00:27:00
Speaker
they're starting to limit the amount of time and practice where you can do full contact. Yeah, exactly. Because of that type of injury that I had banging into each other and practice a lot. And it's a lot of minutes of time of contact. So it begs the question, if you're trying to limit the amount of time you can actually practice or play the sport, does it make sense to be doing it at all?
00:27:27
Speaker
No, it doesn't. Well, yeah, I mean, I think it's controversial, right? It is controversial. But we have some evidence that we'd like to bring to the table here. That's the scientific evidence. And I think we should maybe should should we take a little break and then get back and talk about the paper? Paper? Yeah, sounds good.
00:28:13
Speaker
Okay, and we're back. So what we want to do now as we usually do on the show is to discuss an original
00:28:22
Speaker
paper on the topic. And the paper that we have for today is one from 2017 called clinical pathological evaluation of chronic traumatic encephalopathy in players of American football. And this is by a whole bunch of authors. The first author on this is Jesse Mez. And there are about 25 other authors on this large study and the
Scientific Studies on CTE
00:28:50
Speaker
The outline of this study is that it is done on football players whose brains were donated for research. So these are deceased football players of all different levels who donated their brains to research and then they were examined in detail. And I think of these 202 football players, 177 of them had
00:29:17
Speaker
CTE or this more severe form of damage. Right, so it's kind of an amazing number if you think about it. Of 202 deceased former football players, CTE was neuropathologically diagnosed in 177 players.
00:29:40
Speaker
I don't want to make too much of that because they try to make it clear that this is a sample of convenience. My guess is that the reason why these players donated their brains to science is because they or their families notice some serious cognitive impairments.
00:30:02
Speaker
thought it was worthwhile to study this kind of thing, so we should say that this doesn't necessarily give you an accurate assessment of overall football players and what their, how severe their damage might be. But it is still, despite that, these are people with some serious damage. It's not going to let you know what the
00:30:27
Speaker
We wouldn't say that 80% or 90% of football players have serious traumatic damage.
00:30:37
Speaker
There are actually a lot of limitations of this study, several of which they mentioned, but probably better to sort of talk first about how the study was done and what it's actually showing. And then we can talk about some of the limitations, which are very real. This is kind of why this is an interesting piece of literature, because it is a very dramatic result, got a lot of attention.
00:31:00
Speaker
and says some pretty profound things, I think, but it's also very controversial because it does have some very serious limitations. So I think it's interesting from that perspective. So let's think about who the players are that they're talking about. Now, I think they put out a call for just football players in general. Right, they were advertising this donation program that if you're a football player,
00:31:32
Speaker
you can donate your brain to science. And, you know, they recruited people through networks of friends and family, etc. And they got players from a variety of different backgrounds. And this is a pretty big study. I mean, to get 202 brains for a study like this is pretty amazing. So I think it's fantastic in that respect, for sure. Right. And so they had
00:31:59
Speaker
Two pre-high school players, so players who never played in high school, 14 high school players, players who played up through high school, 53 college players, 14 semi-professional, eight Canadian football league players, and 111 NFL players, national football league players.
00:32:20
Speaker
That's right. So a large proportion of these were professional or semi-professional players. And then of the remaining players, most of them were college. So it's the kind of population that you would want to look at. So it's not just high school football players. Yeah, you want to look at a range also of exposure to contact over time, which this study has somewhat, somewhat.
00:32:50
Speaker
So maybe we could talk about that after we talk about what CTE is in the case of this particular study and then talk about who's being diagnosed with different levels of severity of CTE. Yeah, so CTE
00:33:11
Speaker
Chronic traumatic encephalopathy is a more advanced form of brain damage, you know, that is a result of concussion. It's not entirely clear how
00:33:25
Speaker
this develops over time, a concussion could resolve over the course of a couple weeks or months and no further damage, or you could see these same symptoms and it could worsen to a form of CTE. The way this is diagnosed in this particular study is by looking at brain slices.
00:33:50
Speaker
So the brains of these individuals who donate to the registry, the brains are fixed and then preparations are made up and these slices are analyzed through a microscope and they're stained. And the staining is looking for these markers of neural damage that has previously been shown to be associated with what's referred to as CTE.
00:34:19
Speaker
So this can be somewhat widespread or localized damage. And the two types that they're looking at are phosphorylated tau and then neurofibrillary tangles. And these are things that would be visible in these kinds of thin slices that you couldn't necessarily see in a person who's still living. Other markers that are associated with CTE and in brains that are,
00:34:48
Speaker
analyzed posthumously in this way would be things like brain atrophy. So the actual volume of the brain tissue itself is reduced and concomitantly the size of the ventricles, the space between the brain tissue is increased.
00:35:08
Speaker
In this case, they're mostly looking at these neurofibrillary tangles and P tau or phosphorylated tau. And they were looking at four stages with the first two stages, stages one and two, being basically just less of these markers.
00:35:27
Speaker
um and being considered a milder form and then stages three and four with more of these more pervasive uh signs of of p tau and neurofibrillary tangles and those that being a more severe form so i guess one of the most
00:35:47
Speaker
I guess one of the results that this gives us is we can look at the severity of damage and we can see if there are any particular brain regions that are being targeted or if it's just overall generalized brain damage, if there's particular areas that we might associate with particular cognitive functions that are being damaged. And there are a few specific brain areas that they talk about now
00:36:15
Speaker
are a significant number of these patients or these brains that had the highest stage of CTE, so the worst damage, 57 out of 177 had that high level of damage, and what you see from those brains is it really does look like across the board you just have a lot of damage throughout the brain. The frontal areas, temporal areas, parietal areas, so just
00:36:39
Speaker
overall general damage to the brain. And as you look at lesser stages of CTE, you see some particular patterns in certain regions of the brain. So you're getting in the lightest stage, first stage, you're getting mostly damage to the frontal lobe.
00:37:02
Speaker
And this is the kind of damage that might affect judgment and decision making, working memory, the kind of damage that might not be noticed right away. So it could kind of pass unnoticed for a bit. And then as you move progressively more and more through stages of CTE, you just accumulate more and more damage in the frontal lobe and then
00:37:25
Speaker
you start getting more in other areas of the brain. Areas like the amygdala, which we know is associated with negative emotions, especially in worse stages, you get damage to the hippocampus. The hippocampus is nearly untouched in early stages, but later on become significantly impaired. So we see serious damages in memory that are probably correlated to these damages, this damage to the hippocampus.
00:37:54
Speaker
That's right. Yeah. So you can see, you know, sort of specific areas being affected more than others. And the frontal lobe topic is something that, you know, you see a lot in traumatic brain injuries, especially associated with these coo counter coo injuries that you would get. That's right. That would be the first, if you're facing head on, you would be most likely to have damage to the frontal lobe.
00:38:18
Speaker
the way that the skull is shaped is such that creates a little bit of like a little table that your brain kind of crashes into in the very front of your brain and in the forward part of your skull. So there's also just some structural shape issues as to why that part of the brain is most often impacted. There's also been some speculation evolutionarily that
00:38:45
Speaker
The frontal lobes being the last part of the brain to evolve as robustly as they are in humans. It's the part of the brain that makes us in some ways most human. There's some speculation that that part of the brain is part of its job is actually to be padding for the rest of the brain. I've not read that before. I mean, think about the whole cortex is a little bit like that, right? The most important parts of the brain for survival. That's right. Yeah, breathing and heart rate and all of that kind of stuff are
00:39:15
Speaker
way in the middle. Yeah. And so the things that are somehow least necessary for survival can evolve on the outside of your brain. It's also a lot of it has to do with just the way that it has more to do with geometry, but there's some speculation around that evolutionarily, which I don't know what to make. So you can get by with less frontal cortex, but you know, why would you? It's better not to. But it's better not to.
00:39:41
Speaker
So one of the things to me this kind of indicates is the spreading nature of the disease too that it may start out in some of these outer structures of the brain and where the damage actually physically was, but it seems to spread throughout eventually. So it's progressive and neurodegenerative too, that it's an active disease. It's not just at the very point where you
00:40:08
Speaker
Where you physically damage that part of the brain and that neurodegenerative piece is probably the least well understood Aspect of it why some people are more susceptible to that than others You know how it what exactly the neuropathology of that is You know is yet to be fully worked out But it has been something that has been observed as you get older if you had brain damage You know traumatic brain injury earlier in your life as you get older
00:40:37
Speaker
The impact of that previous injury is now observed, you know, more. So one of the interesting things with this paper is it gets into looking at the percentages of people with traumatic, with a CTE diagnosed from the brain slices based on how much football they played. Uh, so.
00:40:58
Speaker
Why is that interesting and important? Yeah.
Impact of Football Positions on Brain Health
00:41:00
Speaker
Maybe that was what we call a rhetorical question. Or maybe you were going to answer. But yeah, of course that's interesting, because we want to find out how much play causes damage. Can you get by with is playing high school football, but not following it up with maybe more brutal college or professional football OK? Or is it all pretty damaging? And I think that, you know,
00:41:27
Speaker
The reason why this is especially important in this study is because it is a convenient sample and you don't have a control group who, for example, didn't play football. It's really difficult to say how much of an increase playing football caused in the likelihood of having CTE, but you have some sense of the impact of playing a little bit or playing a lot from just the different levels. So for example,
00:41:52
Speaker
three of the 14 high schoolers in the sample showed signs of CTE. That's 21%. Whereas 110 of 111 of the NFL players, 99% had CTE. And this is where the people looking at the slices didn't know where the slices were coming from. So they didn't know
00:42:15
Speaker
these brains were high school football player brains or professional football players. Yeah, but almost every single one of those professional football player brains had some significant damage. A better way to look at that in a sense would be a correlation of diagnosis of CTE at different levels or stages as a function of
00:42:37
Speaker
total hours of football played, for example. You can really see that curve of what it would look like. You know, one more year of football may cause this much more brain damage. That's right. Exactly. I mean, in this case, they're really collecting their data from informants. So, you know, people who knew the players, their friends, their their spouses, their siblings, neighbors potentially even tell, you know, telling the report, you know, telling the
00:43:07
Speaker
researchers about how much football these guys were playing. So it's a little bit imperfect in that way in terms of how the data is collected. But the pattern is still very intriguing.
00:43:22
Speaker
One other interesting thing that they include here is different positions in football. So if you're thinking about getting into football, what's the worst position to actually play? And it seems like certainly playing alignment is pretty bad. Yeah, every single play, alignment. Yeah, right. So alignment are right in the thick of it. And they're really getting hit a lot.
00:43:48
Speaker
So both offensive and defensive linemen show up as some of the most prominent of the cases and also account for more of the severe cases also. Apart from that, running backs also have a pretty significant
00:44:09
Speaker
sharing this too. Yeah, so if you look at the proportions, 27 cases of severe CTE from running backs and only four of mild CTE, you know, versus linebacker, 12 cases of mild CTE and 14 cases of CTE. So a little bit more balanced. So the cases of mild CTE are
00:44:33
Speaker
more likely to come from players who are getting impacted less frequently. And we see that kickers or punters are the best off with no kickers or punters having severe CGE. And that makes sense. I mean, if we didn't see linemen
00:44:53
Speaker
getting more damage than punters, I think we'd be suspicious. Yeah, clearly the ones that have more impact are seeing it more strongly. And I feel like that's pretty strong evidence of, if you're thinking of kind of a dose response or increased damage due to increased hits, and we just kind of know informally that
00:45:13
Speaker
you know, alignment is going to be hit a lot more than say a tight end. And that's what we see. Yes. And so in addition to these physiological anatomical changes that were observed in the brain slices, they also collected data from the informants about some clinical symptoms. So things like cognition and emotion. And I would imagine they didn't have info for all of this because obviously they're dead.
00:45:43
Speaker
Right, exactly. And they also mentioned that there was just some there were some changes in the way that they were collecting the data. So they were really analyzing the most recent 111 cases. So your most your most prominent cognitive problems are issues with memory.
00:46:03
Speaker
problems with executive function or attention, some even with issues with language. And I guess that relates to that punch-drunk syndrome, where, you know, slurring your words or having difficulty speaking is a characteristic of worse damage. So that kind of issue. And then behavioral and mood issues too. So certainly depression, some impulsivity, we'd expect that from
00:46:29
Speaker
from patients with frontal lobe damage, anxiety, depression, and suicidality. So all kinds of behavioral and mood symptoms pop up here too. And you tend to see these more severely in the severe CTE cases than in the mild CTE cases. And here we also note, so there were some of these patients or some of these brains who are also
00:46:56
Speaker
diagnosed in life with having Alzheimer's or Parkinson's. So there's that connection with Muhammad Ali too. Five of the severe CTE patients had Parkinson's. So if you just look at this paper and just take it at face value,
00:47:11
Speaker
What you're seeing is a pattern where people who play football are very, very likely to have brain damage. And the more you play, the more likely you are to have severe brain damage. And that brain damage will very likely impact you later in your life with real world symptoms that could cause problems in your everyday life. I think that's a pretty clear, clear statement from what the paper is saying. Now, of course, there's a lot more to be said about the validity of the results.
00:47:41
Speaker
Yeah, so what do you see as any issues that we should be watching out for here? I mean, the biggest thing right away off the top, and the authors point this out themselves, is that this is a convenience sample. So these are people who themselves or their family members went out of their way to say, I want to volunteer for this brain donation registry, probably because I'm worried that I have a problem based on things that have happened to me in my life.
00:48:11
Speaker
That's right. Maybe you want to help out through research so that it's less prominent for other players so that they can learn something. Right. So it's a bias sample.
00:48:20
Speaker
they even say so directly in the paper. It's very rare that you would see a very prominent paper directly saying this is a biased sample, and they say that actually directly in the paper. So that's interesting in and of itself. Based on that, what you don't see is you don't see the baseline. This is the biggest problem I had with interpreting this paper. What would I see if I just took age-matched controls, so people of the same age, and mixed in those samples into this
00:48:46
Speaker
where the clinicians didn't know what they were looking at. And I just took 202 people, didn't play football and were just randomly identified and looked at their brains.
00:48:59
Speaker
what were the, what kind of percentages of CTE at different levels of severity, what I see there. This paper doesn't give me any reference for that. Maybe it would be quite similar. I find that hard to believe, but very, it makes it really impossible to more directly interpret the results.
00:49:17
Speaker
Yeah, that's right. Yeah. And in actual fact, so 69 of the brains had a cause of death as neurodegenerative. So they certainly knew that there was a severe neurodegenerative disease. And that is certainly higher than the general population.
00:49:39
Speaker
Another thing that I think is worth noting is that in order of severity from the least severe to the most severe symptoms, you also see an age-related difference too. Patients with less severe damage are younger, is that correct? Yes, that is correct, yeah.
00:50:00
Speaker
and the patients with more severe damage are older. Let's see, the mild patients with mild CTE, the average age of death is only 44. And those with severe CTE, the average age of death is 71. So we're talking about pretty young patients in
00:50:20
Speaker
the mild CTE group and relatively older patients in the severe CTE group. If they hadn't passed away at such a young age, what would their brains look like had they lived longer? Would they have developed a more severe form of CTE?
00:50:40
Speaker
Or maybe they wouldn't. Maybe it would appear the same when they died 30 years later. So to me, that's a bit of an issue to keep in mind, too, that there's a bit of a confound between age and severity of symptoms. And also the fact that these patients had neurodegenerative diseases, some of those players might have developed neurodegenerative diseases, never having played football. Right.
00:51:10
Speaker
And maybe it has nothing to do with football. Right. And this is your point where we need a baseline. So we'd want to have an overall, we really want a nice control group that we can say in the absence of playing football, these people lived pretty similar lives. But what are the rates of CTE among those who never played football, but otherwise were similar?
00:51:34
Speaker
The control group that was being suggested in the paper was players who played football but didn't have as many head injuries. I don't know if that's really the right control group because it's hard to know what's happening there. I do feel like you want to have a non-football player control group. You actually need a lot of different types of control groups. Over time, this is something that's going to take time to piece out, piece apart. But it's pretty good. I mean, right. So where does this leave us with this paper?
00:52:04
Speaker
This paper in and of itself to me is merely suggestive. I don't think you can draw any firm conclusions based on this paper, but the suggestion that it's making is incredibly dramatic, incredibly dramatic. The suggestion that it's making is that if you play football and you play it
00:52:30
Speaker
at a high level for a reasonably long period of time, you will have significant damage to your brain. Yeah, and this fits within, you know, even if it's difficult to reach some conclusions with just this research, I think it fits within a larger picture of research that's indicated the same kind of thing. So it's certainly not unreasonable to come to that conclusion, combining this evidence with other evidence out there.
Growing Awareness of Concussion Effects
00:52:55
Speaker
Yeah, I think it's a baseline. I mean, the biggest thing that's changed in our understanding of this work
00:53:01
Speaker
recently, I mean, when I say recently, even over the past 20 years, but even more so over the past five years, is the cumulative effect of multiple concussions. It used to be thought that, oh, you know, you play football, you got your bell rung. That was what you'd say. You got your bell rung. You maybe felt a little bit off for a second. You go into the sidelines, you'd sit down and drink a glass of water. And as soon as you could walk again, you'd be back out there playing again.
00:53:30
Speaker
Right, right. Which now seems like a pretty bad idea. Yeah, it seems like a bad idea. And why is this such a bad idea? Well, as it turns out, you know, your brain goes through all these physiological changes like inflammation, like the neurochemical changes you were talking about before, the neurotransmitter changes that you're talking about. And if you're in that state of fact from the first concussion and you go out and get a second concussion,
00:53:59
Speaker
The second concussion is much, much more dramatic in its impact. Even if you wait a long time between the impacts and the concussions, it can still have a cumulative effect.
00:54:10
Speaker
And this is why college coaches will make sure that you're out and you're not playing for a significant amount of time before you get back in the game. There's something called the second impact syndrome, which is the idea that if the symptoms from a first concussion haven't fully cleared, that a second head injury can be much worse. And even a relatively minor blow to the head
00:54:40
Speaker
could cause you to go into a coma. Now this is something that isn't fully studied, so it's not
00:54:47
Speaker
It's not a guarantee that if you have a concussion, you get hit again, that it's going to cause irreparable damage. But this is a working assumption that I think a lot of coaches will go under, that you really don't want to get a second concussion after that first one if it hasn't cleared up. Yeah. And I think what you see in, for example, all competitive football, but especially you see it in
00:55:15
Speaker
the NFL is there's a lot of pressure on players and coaches to put, you know, put people back in or to go back in when you maybe aren't really quite ready. Yeah. If the, if the, if the goal is to win the game and you need your best player, then yeah, all of the, all of the incentives are towards being more aggressive with putting someone back in. And I think, you know, I watch, I still watch football occasionally. I watch it much less than I used to.
00:55:44
Speaker
You know, it's funny because it's like, it's hard to justify in some ways, knowing some of this stuff.
00:55:50
Speaker
Well, it's funny. This is something, I mean, we almost consider sports heroes to be the athletes that are out there that get severely injured and come back in and win the game. That's right. Come back in and do something miraculous, which is totally stupid, especially if it's a concussion.
Preventing and Treating Concussions
00:56:10
Speaker
Right. I think, well, that gets into the whole hero discussion. So if you're interested in that, you should go back and listen to our hero's pod with Stephanie Preston.
00:56:17
Speaker
Yeah, that's right. That's a good discussion. Yeah. But the, yeah, exactly. I mean, in the case of, you know, some injuries, you know, the threat of re-entry is not so severe. But the case of re-entry here in the case of the brain is really quite important and quite dramatic. And I worry, I look at players like Tom Brady, you know, a guy like that, he's, I mean, he's in his 40s now, and he's still out there doing it. And it's like, every single time he takes a snap, he's reducing
00:56:46
Speaker
the probability that he can have a quality.
00:56:49
Speaker
late life. I mean, it's probably really in some sense past that already, that threshold. Yeah, it's a risk. See how it plays out for him. But each additional snap is just increasing that, you know, that probability more and more. I mean, it's also just interesting how with a guy like that, too, you see how he talks about his concussion history versus, for example, how his wife talks about his concussion history. It's very different. It's very different. There's a tremendous incentive to downplay
00:57:18
Speaker
how many concussions you've had or the severity. That's a male kind of thing, right? You don't want to show that you're hurt. You want to appear strong. Right. I think it's also just the athlete thing. Probably all athletes are doing that, right? They want to be out there playing their game. Yeah. It means more to them than their brain. Yeah. People are wanting to risk a lot. So yeah. So I mean, I think at the end of the day, I think where we're left with this is that there's a lot of evidence that getting a concussion is bad for your brain.
00:57:48
Speaker
getting multiple concussions in general is bad for your brain. It's worse than just getting one, getting multiple concussions in close proximity is especially bad for your brain. And this is something that players, coaches, and parents need to take very seriously. Any last words we want to have about this? No, I think in general,
00:58:10
Speaker
Well, I mean, yes. I should say yes. Well, I'll say too. So what I'm thinking of here is just having this on your mind and thinking about this could be useful, right? So if you're not thinking about avoiding reckless kinds of things, you're not going to avoid them. But having this on your mind, especially as you're doing, engaging in any of these sports might be helpful.
00:58:32
Speaker
but maybe cut down on the reckless things that you do. But even more important, I guess, is thinking about treatment, that the first hour or so after getting a severe concussion can be really important in getting it treated. So get to an emergency room right away and let a professional take over care of you so that you can get some immediate treatment, which could reduce the longer term effect of some of these kinds of things. And if you've had a concussion,
00:58:59
Speaker
you know that's giving you maybe some problems now and you haven't seen a doctor certainly go to a doctor and talk to them about it. And taking the time that you need off after a concussion to recover before you get it back out and playing again is super important and is going to be very helpful in making it less likely that you have serious problems down the road.
00:59:20
Speaker
Life is full of trade-offs and you have to think about what's important to you and what risks you're willing to take. You can't go through life not taking any risks. That doesn't work. For some people, playing football will be worth the risk, but it's important to do it with eyes open and understanding what the consequences could potentially be. All right.
00:59:36
Speaker
Well, thanks for listening. Yeah. And if you want to, uh, you know, support the show, you can rate or review us on, uh, iTunes or whatever podcast network that you're listening to us on. Also like our homepage on Facebook, cognition podcast. And if you have any, uh, feedback that you'd like to give us, you can, uh, add us on fit on Twitter, uh, or at nation cog, or you can just look at, look up cognition on Twitter and you can find us there.
01:00:05
Speaker
and we'd love to hear from you there or on the Facebook page. Thanks for listening.