Decoding CTE

Summary

All Of It: Decoding CTE
Hosted by Alison Stewart | Released August 4, 2025 | WNYC

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Introduction and Context

In the episode titled "Decoding CTE," Alison Stewart delves into the complex and pressing issue of Chronic Traumatic Encephalopathy (CTE), a neurodegenerative disease closely linked to repetitive head impacts commonly seen in contact sports and military service. The episode opens with a somber reminder of the recent tragic shooting in New York City, where a former high school football player claimed CTE as a motive—a stark illustration of the disease's potential impact on behavior and mental health.

Understanding CTE

Definition and Symptoms
At [00:09], Alison Stewart introduces Dr. Jesse Mez, an Associate Professor of Neurology at Boston University and an expert on CTE. Dr. Mez begins by defining CTE:

"CTE stands for Chronic Traumatic Encephalopathy. It's a neurodegenerative disease not unlike Alzheimer's disease. We know that it almost always occurs in the setting of repetitive head impacts, usually from contact sports or military exposure. It is a slowly progressive disease that has symptoms including cognitive impairment like memory problems, executive function problems, as well as behavior problems like behavioral dysregulation or a short fuse." ([02:02])

Executive Function Explained
Alison seeks clarification on "executive function problems," to which Dr. Mez elaborates:

"So that's things like problem solving, set shifting, being able to hold multiple things in your mind and manipulate both of them together." ([02:34])

Historical Perspective

Origins of CTE Research
Dr. Mez provides a historical overview, noting that CTE was first identified in boxers in 1928 by Martin. It wasn't until the mid-2000s that CTE was recognized in American football players, significantly expanding the understanding of the disease beyond boxing.

"CTE is not a new disease. It was first described by Martin in 1928 in boxers... In the mid 2000s, it was first described in an American football player." ([02:49] - [03:20])

Prevalence and Risk Factors

Dose-Response Relationship
A key concept introduced is the dose-response relationship between the number of head impacts and the risk of developing CTE. Dr. Mez explains:

"The more you've played, the bigger your risk... for each additional year played, the odds of getting CTE increased by about 30%... from one or two years of football all the way up to 25 plus years." ([04:34] - [05:03])

Affected Populations
CTE predominantly affects those with extensive exposure to contact sports, including high school and college athletes, with higher prevalence in professional players. Additionally, military personnel exposed to repetitive head trauma from blasts or equipment also show potential risk, though research in this area remains limited.

Personal Stories and Inquiries

Listener Engagement and Personal Stories
Throughout the episode, Alison invites listeners to share their experiences with CTE. Two notable calls provide deeper insight into the personal impact of head injuries and familial ties to neurodegenerative diseases.

1. Adrienne's Story
   Adrienne shares her husband's severe brain injury from 1989, his long recovery, and the family's history with Alzheimer's:

   "So I was wondering if a head injury and the Alzheimer's hereditary in the family can lead to this diagnosis also that this football players and everybody experiences." ([07:07] - [07:56])

   Dr. Mez responds by differentiating between single traumatic brain injuries and the repetitive impacts associated with CTE, explaining the complexities in linking head trauma to specific forms of dementia:

   "A single or even a handful of moderate to severe traumatic brain injuries is not linked to chronic traumatic encephalopathy, but it is linked to dementia." ([08:00] - [10:16])

2. Katie's Inquiry
   Katie from the Bronx asks about modifications in tackling techniques to reduce CTE risk:

   "Would that help ameliorate this impact of this high contact input impact on this Type of the CTE condition?" ([11:35] - [12:29])

   Dr. Mez emphasizes reducing the number and force of head impacts as the most effective strategy:

   "I think the best approach is to reduce the impacts... playing flag football as long as you can before moving to contact." ([12:30] - [13:33])

Richard's Question on Divers
Richard raises a unique point about whether repetitive impacts in sports like diving could lead to CTE:

"Olympic divers... they are really hitting the water at high velocity... any research on that type of sport?" ([13:35] - [14:23])

Dr. Mez acknowledges the gap in research, noting the absence of CTE cases among divers in brain banks but cautions that the sample size is too small to draw definitive conclusions.

Symptoms Onset and Behavioral Implications

Immediate vs. Long-Term Symptoms
Alison inquires about the timeframe for symptom manifestation post-impact. Dr. Mez explains the distinction between concussions and the cumulative effects leading to CTE:

"You can have a fairly big stroke sometimes and not show any symptoms at all... It's the repeated forces over many years that are important." ([14:50] - [17:03])

Behavioral Dysregulation and Aggression
When discussing behavioral symptoms, Dr. Mez notes that aggression may manifest earlier and is not solely explained by tau protein accumulation associated with CTE:

"It's likely that it's the CTE pathology is only contributing to some extent to the behavior problem... neuroinflammation, white matter injury, breakdown of the blood brain barrier." ([17:21] - [18:39])

Hope for the Future: Research and Diagnosis

Advancements in Diagnosis
Dr. Mez shares encouraging developments in diagnosing CTE during a person's lifetime, drawing parallels with other neurodegenerative diseases:

"We want to get to the same place with CTE... developing these biomarkers, either PET imaging or from cerebrospinal fluid or blood based, looking at changes in proteins." ([18:47] - [19:59])

Correcting Misconceptions
Addressing media portrayals, Dr. Mez emphasizes understanding the dose-response relationship and avoiding fear-mongering:

"It's important to understand this dose response relationship... it's a slowly progressive disease... people with these changes in their brains can still lead hopeful, meaningful lives." ([20:07] - [21:00])

Conclusion

Alison Stewart wraps up the episode by thanking Dr. Mez for his insights and encouraging listeners to continue the conversation around CTE openly and responsibly.

"My guest has been Dr. Jesse Mez... Thank you so much for your expertise and for sharing it with our audience." ([21:00] - [21:10])

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Key Takeaways:

• CTE Definition: A neurodegenerative disease linked to repetitive head trauma, affecting cognitive and behavioral functions.
• Historical Context: Initially identified in boxers, with increased recognition in football players since the mid-2000s.
• Risk Factors: Higher exposure to contact sports correlates with increased CTE risk.
• Symptom Onset: CTE symptoms develop slowly over years, distinct from immediate concussion effects.
• Behavioral Effects: Aggression and behavioral dysregulation may emerge independently of tau pathology.
• Research Advances: Ongoing efforts aim to diagnose CTE in living individuals through clinical criteria and biomarkers.
• Preventative Measures: Reducing the number and force of head impacts in sports is crucial for mitigating CTE risk.

This episode provides a comprehensive overview of CTE, blending expert analysis with personal narratives to illuminate the multifaceted nature of the disease and its implications for athletes and society.

Transcript

[Alison Stewart]

This is all of it on wnyc. I'm Alison Stewart and listeners, we want to give you a note that this segment may contain references to violence and suicide. If you or someone you know is considering suicide or in a crisis, please call or text 988-to reach the Suicide and Crisis Lifeline. Last week, new York City witnessed its deadliest shooting in nearly 25 years. Four people were killed by a man who then took his own life. As the investigation into motives for the shooting unfolded, a note was found where the shooter, who had been a high school football player, claimed to have cte. This is not the first time the condition of CTE has been in the news. Former New England Patriots star Aaron Rodriguez committed murder before killing himself and was found to have one of the most severe cases of CTE for his age group. He was just 27. A number of former players, including former Chicago Bears David Duerson, has left suicide notes asking for their brains to be studied for the disease. To understand more about the disease and how it's being studied and why it's so hard to diagnose in the living and why it's so closely linked with football, we've invited Dr. Jesse Mez, an associate professor of neurology at Bradford Boston University and an expert on CTE, to join us. Welcome, Dr. Mez.

[Dr. Jesse Mez]

Thanks so much for having me.

[Alison Stewart]

Listeners, do you have any questions about CTE for Dr. Mez or have an experience with CTE in your own life or a family member or a friend or a colleague? We would like to hear your stories. Our phone lines are open, 212-433-WNYC 212-433-96992. I'm going to get you to explain what CTE is. I had it written out, but I decided to let you do it instead.

[Dr. Jesse Mez]

Sure, sure. So CTE stands for Chronic Traumatic Encephalopathy. It's a neurodegenerative disease not unlike Alzheimer's disease. We know that it almost always occurs in the setting of repetitive head impacts, usually from contact sports or military exposure. It is a slowly progressive dise that has symptoms including cognitive impairment like memory problems, executive function problems, as well as behavior problems like behavioral dysregulation or a short fuse.

[Alison Stewart]

When you say executive function problems, what does that consist of?

[Dr. Jesse Mez]

So that's things like problem solving, set shifting, being able to hold multiple things in your mind and manipulate both of them together.

[Alison Stewart]

When was CTE first recognized?

[Dr. Jesse Mez]

So CTE is not a new disease. It was first described by Martin in 1928 in boxers. For most of that time, it was only thought to be found in boxers. In the mid 2000s, it was first described in an American football player. And that's sort of when our modern conception and these new ideas about CTE have come about since then.

[Alison Stewart]

Who does it typically affect?

[Dr. Jesse Mez]

So what we know is there is a dose response relationship between the amount of contact sport play and other types of repetitive head impacts and risk of getting this disease. So it affects those who have played the most. So we typically find it among elite contact sport athletes. They can be either amateur or professional, but it's those who have played the most.

[Alison Stewart]

When you say amateur, do you mean college?

[Dr. Jesse Mez]

Do you mean high school? Yes, that's. That's so. So we have seen it in college players. We've seen it in the high school players. It's like I said, it's this dose response relationship. So it's rare in, in the high school players, and it becomes more common in, in the college and the professional players. We've always studied it in the setting of a brain bank and folks who have donated their brain. So I use these somewhat vague words like rare or less rare, but we don't. Absolutely. We don't actually know the actual prevalence of the disease, because we don't. We don't. We aren't able to diagnose it in life.

[Alison Stewart]

And I want you to explain to people what a dose relationship is.

[Dr. Jesse Mez]

Right. So it basically means the more you've played, the bigger your risk. So, for instance, we did a paper where we showed that for each additional year played, the odds of getting CTE increased by about 30%. And we showed that relationship across a really big range of exposure, from one or two years of football all the way up to 25 plus years.

[Alison Stewart]

All right, so we associate it with football. You, you mentioned boxing. I'm guessing hockey players are in there, too. But you did mention the military. How do soldiers get it?

[Dr. Jesse Mez]

Right? So we know a lot less about military and the relationship to cte. We do know that those in the military play a lot of context sports. So part of the reason that the military gets it is because they're playing a lot of context sports. But we also know that the repetitive hits from blasts or from arms used over many years seems to be a risk. But again, this is early days in small numbers.

[Alison Stewart]

My guest is Dr. Jesse Mez, Associate professor of Neurology at Boston University. Listeners, if you have any questions about CTE for Dr. Mez or have an experience with CT in your own life, we'd love to hear your story. Our number is 2124-3396-9221-2433. WNYC. Before we go any further, Dr. Mez, how did you get interested in this?

[Dr. Jesse Mez]

Yeah, so I'm trained as a behavioral neurologist, so really in the aging and dementia space. And I really thought my career would be mostly about Alzheimer's disease. And I'm also really interested in genetics. And while I was in my training, one of the leaders of our center, Dr. Ann McKee, a neuropathologist, came and gave grand rounds and talked about this disease, and I was pretty fascinated. And they were looking for a behavioral neurologist. So it was a perfect match.

[Alison Stewart]

This is a call from Adrian on line two. Adrienne, thank you so much for sharing your story with us.

[Adrienne]

Thank you. So my question is, should I just go right to the question?

[Alison Stewart]

Yes, please.

[Adrienne]

Okay. So my husband had a massive brain injury in 1989. And when I say massive, I mean massive. He was in a coma for 22 days. He was incapacitated for about seven years. And they consider him a walking miracle. Now, my mother in law and my grandmother, my mother in law and my grandmother in law, his mother and grandmother both died very, very long deaths from Alzheimer's. It was nothing else that took their lives. It was Alzheimer's. So I was wondering if a head injury and the Alzheimer's hereditary in the family can lead to this diagnosis also that this football players and everybody experiences.

[Alison Stewart]

Thank you so much for the call, Dr. Mez. Do you feel comfortable answering that?

[Dr. Jesse Mez]

Yeah. So that's, that's a good question. And it gets at a lot of the nuance related to Alzheimer's, neurodegenerative disease and head trauma. Right. So. So we have known for many years that traumatic brain injury, this is typically a blow that results in symptoms. Sometimes those symptoms can be really severe, like leading to bleeding in the brain and coma. Like the caller mentioned, we know that those are linked to dementia. Dementia is a progressive disease with cognitive impairment and functional impairment, impairment in activities of daily living. There are many causes of dementia, the most common of which is Alzheimer's disease. CTE is a much less common cause of dementia. CTE is linked to these repetitive hits, like these thousands of hits over a context board career. So a single or even a handful of moderate to severe traumatic brain injuries is not linked to chronic traumatic encephalopathy, but it is linked to dementia. Whether that dementia is caused by Alzheimer's pathology is still a bit up in the air. There is really Mixed research on this relationship between single or multiple, but just a few traumatic brain injuries and Alzheimer's disease. It's possible that these traumatic brain injuries lead to a unique pathology that's not Alzheimer's and not cte. That leads to the dementia and probably the traumatic brain injuries. And if you also have Alzheimer's, changes in the brain, it makes everything worse. But trying to disentangle these complexities is. Is a work of a lot of researchers, including myself.

[Alison Stewart]

A 2023 report from Boston University showed that nearly 90% of football players who had donated their brain to the Boston University center had cte. Could you tell us a little bit about this group of players?

[Dr. Jesse Mez]

Right, so we have the largest brain bank in the world of individuals who had exposure to brain trauma, most of which is repetitive head impacts from contact sports and military service. Most of them were elite players, so they had overwhelming exposure and most of them had symptoms. And their families were concerned about what was going on and they wanted some answers. So these inflated numbers that we report in the papers are important to show that there is this dose response relationship and that it's possible that this disease is not rare. But those exact numbers aren't representative of how common this disease is in the general population.

[Alison Stewart]

Let's take another call. This is Katie from the Bronx. Hi, Katie, thank you so much for calling, all of it.

[Adrienne]

Hi, thanks so much for having me. And thanks for. This is a great topic. Thanks for covering it.

[Dr. Jesse Mez]

Thanks.

[Adrienne]

So I was calling because my brother was, for years, he was a high school football coach. And this is really front and foremost for probably a lot of high school football coaches. And one thing that he did was he started to work on training the rugby tackle, which instead of being focused on head to head or at the shoulders, is at the legs. And, you know, in the interest of helping the kids and obviously preventing these types of injuries, I'm curious if that were adapted in a more global sense, say from amateur to a, through professional, if the rules change all that, hypothetically, would that help ameliorate this impact of this high contact input impact on this Type of the CTE condition? Sorry. And that's it.

[Alison Stewart]

What do you think, Dr. Miz?

[Dr. Jesse Mez]

Yeah, so I think that we know about this dose response relationship. The more impacts and the harder those impacts are, the greater the risk. I think the best way to ameliorate these issues is to reduce the number of impacts and the force of those impacts. I think what that means is playing flag football as long as you can before moving to contact. It means not hitting during practices, and it means reducing hits as much as possible during games. We see CTE in rugby players as well. So while it is possible that differences in tackling may lead to differences in those forces, I think the best approach is to reduce the impacts.

[Alison Stewart]

Let's talk to Richard, who is calling in from Babylon with a question. Hi, Richard, you're on with Dr. Jesse Mez.

[Richard]

Yes, Dr. Mez, I had a curious question with the. You know, the contact sports you're really talking about are, you know, they're usually protected with some helmets of some type. But when you look at, like the Olympic divers, the platform divers and springboard divers, they are really hitting the water at high velocity. And obviously the intent is to make as little splash as possible, but they are basically trying to punch their way through into the water. And most of the divers start at a very young age, and it is a repetitive many hours a day practice to become proficient in that. I was wondering if there's any research that you're looking into on the effects of that type of sport.

[Dr. Jesse Mez]

Yeah, no, that's a good question and definitely a good thought and on point in terms of this repetitive nature of the impacts. As my understanding is, we don't have any cases of divers with CTE in the brain bank. That being said, we don't have many divers in the brain bank either. So I think it's still an unexplored question.

[Alison Stewart]

Let's say someone has some sort of impact. Football player, two helmets, soccer players butting heads. How soon will the symptoms after a concussion, how soon will they start to show?

[Dr. Jesse Mez]

Right. So I think we should differentiate. Well, I think we should get some terminology. Please, please, please. So a concussion is when you have a blow to your head or your body and you have resulting neurologic symptoms, right. Immediately thereafter, you can also have a blow to your head or your body, where you don't have any symptoms at the time of that impact. But there are still biological changes that are happening in your brain. For instance, we know that the forces in football that often result in a concussion can be just as large and not result in any symptoms as well. This is really because your brain has a lot of different functions. You can actually have a fairly big stroke sometimes and not show any symptoms at all. The relationship between these impacts and symptoms immediately is complex. What we also know is that it's these repeated forces over many, many years, regardless of. Of whether they cause symptoms at the time of the impact. That seems to be what's important. You can smoke cigarettes for years and Years and not have any symptoms from your cigarettes, but then develop cancer years later. It's the same type of concept. We also know that with cte, it's caused by this protein, tau, that accumulates. And we've also shown that the more tau that accumulates, the more symptoms of CTE that we see, the more memory, the more problem solving, the more behavioral dysregulation.

[Alison Stewart]

When you say behavior, can I dive in real quick? Because when you say behavioral dysregulation, my mind immediately goes to the aggression that we've seen in these recent cases. When is it more likely to happen? When CTE morphs into aggressive behavior?

[Dr. Jesse Mez]

Yeah. So the aggressive behavior is also complex. We know pretty well that the more CTE pathology you have, the more tau pathology you have, the more cognitive symptoms, the more memory and executive function. But those behavior symptoms often happen earlier when there is less pathology in the brain. The tau pathology from our studies explains far less of the variance in the behavior symptoms. So it's likely that it's the CTE pathology is only contributing to some extent to the behavior problem. So it's things like neuroinflammation, white matter injury, breakdown of the blood brain barrier, but it might not be CTE per se that's causing some of those behavioral symptoms. We also know that brain trauma, not even considering cte, is related to more aggression, more depression, more suicide. Whether or not there are these neurodegenerative changes of cte, there is almost secondary. When we're thinking about these behavioral changes.

[Alison Stewart]

What are some of the findings that you and your team and the center does that have you feeling hopeful?

[Dr. Jesse Mez]

So there is a big effort to diagnosis disease in life. Right. So we have diagnosed other neurodegenerative diseases in life for many, many years. We can only make a diagnosis with absolute certainty after death. And this is the case for Alzheimer's disease, for Parkinson's disease, for cte. But that doesn't stop us from making these other diagnoses in life based on clinical syndrome and sometimes biomarkers. And we want to get to the same place with cte. And we have multiple studies underway. We have proposed criteria to diagnose CTE in life called traumatic encephalopathy syndrome. And we've been trying to validate those criteria. I was actually just at a meeting where we presented some promising results from that. And then we're also working hard to develop these biomarkers, either PET imaging or from cerebrospinal fluid or blood based, looking at changes in proteins. And we hope that all of those are pathways to diagnosis in life in the future.

[Alison Stewart]

Is there one piece of information that you'd like to correct that you've heard repeated in the media?

[Dr. Jesse Mez]

I think that it's this, I think it's really important to understand this dose response relationship that the more you play, the more the risk. And also to understand that it's the, this slowly progressive disease that is, is generally something that, that is not a death sentence by, by any stretch. It's, it's very slow. I think it's probably slower than Alzheimer's disease and that people with these changes in their brains can still lead hopeful, meaningful lives. And I think it's important to talk about these things openly, but not to have this fear mongering related to it.

[Alison Stewart]

My guest has been Dr. Jesse Mez, Associate professor of Neurology at Boston University. Thank you so much for your expertise and for sharing it with our audience.

[Dr. Jesse Mez]

Thank you for having me.

[Alison Stewart]

And that is all of it for today. I'm Alison Stewart. I appreciate you listening and I appreciate you. I will meet you back here tomorrow.

[Adrienne]

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[Alison Stewart]

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