It's a common sight on Sunday afternoon. The snacks are gathered. The couch cushions are plumped. The beer is cold. Across the screen, twenty-two people in tight white pants and polished helmets trot across the screen. But behind the shiny exterior of football, America's favorite pastime, lies a dark secret - chronic traumatic encephalopathy (a word I am incapable of pronouncing). A neurodegenerative disease characterized by psychological, behavioral, and cognitive changes, CTE and repeated head trauma has been linked to rage behaviors and increased aggression. In fact, Aaron Hernandez, a former NFL player was posthumously diagnosed with advanced CTE, potentially providing a "why" for his brutal murder of Odin Llyod.
If you have any comments, questions, concerns, queries, or complaints, please email me at NeuroscienceAmateurHour@gmail.com or DM me at @NeuroscienceAmateurHour on Instagram. Citations and relevant papers below:
NFL Helmet Challenge Raises the Bar for Helmet Technology and Performance, Awards $1.55 Million in Grant Funding to Help New Models Get on Field Faster. NFL.com. https://www.nfl.com/playerhealthandsafety/equipment-and-innovation/innovation-challenges/nfl-helmet-challenge-raises-the-bar-for-helmet-technology-and-performance-awards Published 2021.
Built By Data: NFL Helmet Innovation. NFL.com. https://www.nfl.com/playerhealthandsafety/equipment-and-innovation/engineering-technology/built-by-data-nfl-helmet-innovation. Published 2021.
Heintz E, Breaux L, Lewis A, Foreman J. Determinants of Missed Games Following Concussions in the National Football League. Front Sports Act Living. 2020;2. doi:10.3389/fspor.2020.595445
Tator C. Concussions and their consequences: current diagnosis, management and prevention. Can Med Assoc J. 2013;185(11):975-979. doi:10.1503/cmaj.120039
Mez J, Daneshvar D, Kiernan P et al. Clinicopathological Evaluation of Chronic Traumatic Encephalopathy in Players of American Football. JAMA. 2017;318(4):360. doi:10.1001/jama.2017.8334
McKee A, Stein T, Kiernan P, Alvarez V. The Neuropathology of Chronic Traumatic Encephalopathy. Brain Pathology. 2015;25(3):350-364. doi:10.1111/bpa.12248
Asken B, Sullan M, DeKosky S, Jaffee M, Bauer R. Research Gaps and Controversies in Chronic Traumatic Encephalopathy. JAMA Neurol. 2017;74(10):1255. doi:10.1001/jamaneurol.2017.2396
Turner R, Lucke-Wold B, Robson M, Lee J, Bailes J. Alzheimer’s disease and chronic traumatic encephalopathy: Distinct but possibly overlapping disease entities. Brain Inj. 2016;30(11):1279-1292. doi:10.1080/02699052.2016.1193631
Giza C, Hovda D. The New Neurometabolic Cascade of Concussion. Neurosurgery. 2014;75:S24-S33. doi:10.1227/neu.0000000000000505
Haislop T. Aaron Hernandez timeline: From murders and trials to prison suicide. Sportingnews.com. https://www.sportingnews.com/us/nfl/news/aaron-hernandez-timeline-murders-trials-prison-suicide/1886y82a8bgyx123qxcgg04lb5. Published 2020.
Support the show
Hello! My name is Barbara and this is Neuroscience: Amateur Hour.
Welcome back! Thank you so much for tuning back in. Today I want to chat with you about America’s favorite pastime - football! And the traumatic brain injuries that players can incur.
Before I delve deep, I would like to make a disclaimer that I am a researcher and not a medical professional. If you feel that you are having any health or mental issues, please contact a healthcare professional! Cool! Let’s get into it!
It's a common sight on Sunday afternoons. The snacks are gathered. The couch cushions are plumped. The beer is cold. Across the screen, twenty-two people in tight white pants and a truly incredible amount of padding trot onto the field. The stands are filled with cheering spectators and cheerleaders shake their pom-poms from the sidelines. The stadiums are filled with raw aggression, seemingly modern-day gladiators before the masses.
For those of you who aren't sports fans or are not from the United States, football has very little to do with connecting a foot to a ball.
The rules of the game are thus. Two teams of eleven players face off against each other on a rectangular field with large goalposts on either side. The offensive team which is in possession of the ball attempts to get it to the other end of the field by throwing it or passing it from player to player without dropping it. The defensive team tries to stop their attempts and take control of the ball for themselves.
This goes back and forth across the field until someone gets the ball to the other side and scores a touchdown in the end zone, scoring 6 points. If the offensive team is close enough to the goalposts, they will attempt a field goal where a kicker kicks the ball through the goalposts, collecting 3 points. Additionally, the defensive team can gain 2 points if they tackle a member of the offensive team with the ball in their own end zone.
Games are about 1 hour long, divided into four quarters of 15 minutes each. They are typically played in a series of downs, individual plays of short duration.
If you can’t guess, in order to stop the opposing team from getting the ball to the end zone and scoring a touchdown, there’s quite a bit of full contact that occurs between players. Look up any high school or college game and you will see that football is chock full of people ramming into each other, tackling each other, falling onto the field, banging their heads, and generally colliding in all manner of ways.
To combat the inevitable injuries, football players do wear a lot of padding. They’ve got shoulder pads, arm pads, elbow pads, butt pads, backplates, rib protection, girdles, mouth guards, and helmets.
The helmets themselves are feats of innovation. They need to be able to block both linear force and twisting forces from impacts. One new helmet technology is called multi-directional impact protection system (MIPS). Manufacturers add a molded plastic layer between the hard outer shell of the helmet and the interior padding. This allows the plastic layer and the outer shell to rotate independently, reducing the strain on the player's head and brain.
After denying the severity of player injuries for years, the national football league, the NFL, has now shifted gears and is leading the charge for better helmets and improving player safety. In October of last year, they announced the results of the $3 million dollar Helmet Challenge, a competition designed to accelerate helmet performance and safety for NFL players. After two years of work, 13 teams made up of biomechanical engineers, materials scientists, and current manufacturers submitted their prototypes for testing and judging.
Three teams from the United States and Canada were collectively awarded the grant money to continue developing their products which combine cool new materials and designs to absorb shock and be more comfortable for players.
But despite all of these efforts, it is not a secret that footballers are prone to concussions. A concussion is a traumatic brain injury caused by a bump or jolt to the brain that causes your brain to effectively jiggle back and forth inside your skull. Imagine your head is a raw egg and your brain is an egg yolk. Shake the egg back and forth and the yolk will hit the shell inside the egg.
The exact mechanisms of concussion are largely unknown. Some researchers theorize that concussions could cause neurons to literally tear apart but more importantly, the jiggling of the brain produces disordered metabolic cascades or biochemical injuries of some sort.
Neurotransmitters are released at random and neurons fire haphazardly. In order to restore balance, the sodium-potassium pump that is situated in the neuronal membrane and functions to maintain a specific membrane potential starts working overtime and consuming massive amounts of ATP - the energy of the body. This results in a dramatic jump in glucose metabolism and then a subsequent drop and energy crisis in the brain.
Concussions are often accompanied by headaches, nausea, vomiting, balance problems, sluggishness, confusion or memory problems, or feeling generally more emotional. While deeply concerning, most concussion symptoms are transient and dissipate within 1-2 weeks with adequate rest.
However, there are a number of more severe neurological and psychological disorders that occur post concussions. One of these is second-impact syndrome which is where the brain swells rapidly shortly after a person incurs a second concussion within a short amount of time of the first. This event is very rare but also often fatal. Some people have concussion symptoms that may persist for weeks or months and some may develop post-traumatic epilepsy or seizures.
There have also been reports of psychological changes with people developing depression, anxiety, etc after a concussion which makes sense given that your brain is literally being shaken back and forth like a martini and your brain tries to restore balance and it might not always be successful.
For your average football player, a concussion is a semi-regular occurrence. In the NFL specifically, there are approximately 140 concussions reported per season and it is estimated that at least one player on a team suffers a concussion every five games. There may be more that are unreported.
As I mentioned before, concussions on their own are not big deals. After a few weeks of downtime, your poor bruised brain is back to normal without any long-term consequences. But the prevalence and frequency of traumatic brain injuries pose a much larger problem.
Specifically, I mean chronic traumatic encephalopathy or CTE is a rare condition used to describe brain degeneration likely caused by repeated head traumas. That means that over time, your neurons die and certain regions of your brain shrink.
The diagnosis is usually done during an autopsy where the physician looks at thin slices of the brain to determine whether any regions of the brain have shrunk. It cannot be diagnosed during life except maybe in individuals with high-risk exposures such as football players, people who play other full-contact sports such as boxing, and military personnel who are exposed to explosive blasts.
Why has CTE been linked specifically to football players beyond the fact that it's a full-contact sport? I found this paper from the Journal of the American Medical Association, published in 2017 with a mind-boggling 19 authors from the Boston University School of Medicine in Massachusetts. The purpose of the paper was to determine whether players of American football could be at increased risk of long-term neurological conditions, specifically CTE.
Before I get into the truly what the fuck results, please note that this data was gathered from a convenience sample of deceased football players who had donated their brains for research so its not exactly a random sample of football players but people who may have had some neurological issues and played football and were like there’s probably something wrong up in my head, I should donate my brain to science.
Ok so of the 202 deceased football players, researchers observed that 177 of them were neuropathologically diagnosed with CTE. That's a staggering 87%. Please note - that doesn’t mean that 87% of football players have CTE.
These researchers found that severity of CTE was distributed across the highest level of play, with all 3 former high school players in their sample having mild pathology and the college, semi-professional and professional players having severe pathology. Of the participants with mild CTE, 96% had behavioral or mood symptoms, 85% had cognitive symptoms and 33% had dementia. Of the patients with severe CTE, the numbers were similar with a crazy 85% having dementia.
Protect your brains, ya’ll. That’s all I got to say.
So let's get into some of the symptoms and pathologies! I want to clarify that CTE is not well understood yet so a lot of this information comes with the asterisk *research in progress*.
The disorder is often characterized by cognitive impairment such as difficulty thinking, memory loss and problems planning, organizing, and executing tasks, behavioral changes such as impulsive behavior, and increased aggression. Keep this last one in mind because I recently came across a really interesting article on this subject matter that I will bring up towards the end of the podcast.
Additionally, individuals with CTE may have mood disorders such as depression, anxiety, substance misuse, and suicidal ideation as well as present with motor issues including Parkinson's' disease.
In addition, the increasing attention to CTE has sparked a hunt for biomarkers that could predict the emergence of the disease. One such biomarker is tau protein. Tau is a microtubule-associated protein that lines the inside of a nerve cell and stabilizes it. As the brain deteriorates, it starts to build up huge amounts of the protein tau which becomes hyperphosphorylated and aggregates in something called neurofibrillary tangles.
These neurofibrillary tangles, or NFTs, cluster around the small blood vessels of the cortex which in turn disrupt nutrient supply to brain cells, eventually killing them. If all of this sounds vaguely familiar, it might be because CTE has a very similar pathology to Alzheimer's.
The biggest difference between the two diseases is in the distribution of the tangles. In CTE, the tangles are predominantly in the more superficial layers of the cortex whereas, in patients with Alzheimer's disease, the tangles are predominantly in the deeper layers of the cortex. They are also present in slightly different parts of the brain.
An important question is - are Alzheimer's and CTE distinct diseases or are they somehow related beyond their shared pathologies? One paper, published in 2017, out of West Virginia University School of Medicine looked at the case studies of three patients. One with only Alzheimers pathology, one with only CTE pathology, and one with both. They observed that while the diseases had distinguishing features they also had shared features. They also raised some interesting questions. Does having CTE advance the development of Alzheimer's? Does CTE somehow relate to aging?
While I’m not normally one to leave on a cliffhanger, unfortunately, we simply don’t know the answers to those questions. The intricacies of these diseases are many and complicated and I would argue we need another 10 years of research in this area to truly understand what’s going on.
I want to leave off on a morbid but interesting note. Trigger warning. Murder. Moidor. I’m a huge crime junkie so this part speaks to a special part of my soul.
So in 2020, Netflix came out with a documentary called Killer Inside: The Mind of Aaron Hernandez which examined how Aaron Hernandez went from NFL player to convicted killer and the possible role of CTE in his actions.
On June 26th, 2013, the nation awoke to the sight of Aaron Hernandez, a man who had been a beloved New England Patriot (even making it to the Super Bowl) being escorted out of his house with his wrists in cuffs. Later that day, he was charged with the murder of Odin Llyod, a semi-pro football player who at the time of his death was dating Shaneah Jenkins, the sister of the fiancee of Aaron Hernandez. Lloyd had been found shot to death in an industrial park that was just one mile away from Hernandez’s house, about a week earlier.
On June 16th, technically the early hours of June 17th, Lloyd was a passenger in Hernandez’s car, confirmed through texts with his sister. The two men were apparently in an argument over a bag of marijuana and the keys to a car that had been rented by Hernandez were found in Llyod’s pocket. Prosecutors believe Llyod had said something to Hernandez that had destroyed the player’s trust in Lloyd and given Hernandez a motive to kill.
During his trial, Hernandez was also tied to the deaths of two men shot in Gainesville Florida in 2007 and the shooting and deaths of Daniel de Abreau and Safiro Furtado. Eventually, it was found that Hernandez had likely nothing to do with the former shooting incident and was acquitted in the double homicide of De Abreau and Furtado.
Although he plead not guilty to the death of Odin Llyod, he was found guilty of first-degree murder in 2015 and sentenced to life in prison. In 2017, Hernandez was found dead in his cell by suicide.
He was posthumously diagnosed with stage 3 of 4 of CTE. Hernandez had two confirmed concussions since he began playing football at a young age but took - god knows how many blows to the head over his career. Researchers have suggested that CTE may result in poor judgment, lack of impulse control, aggression, paranoia, anger, emotional volatility, and rage behavior.
Dr. Sam Gandy of Mount Sinai who is a professor of Alzheimer's Disease Research and a Professor of Neurology and Psychiatry stated “It’s impossible to look at the severity of CTE and Mr. Hernandez’s brain and not think that that had a profound effect on his behavior”. While his injuries are no excuse for his despicable behavior as a murderer, they may provide some explanation for why.
People close to Hernandez and those who observed him in prison said he suffered from migraines and memory loss, common symptoms of advanced CTE.
As always, it's impossible to say that Aaron Hernandez’s career in the NFL led to severe CTE that eventually led him to take that life, it cannot be disputed that severe brain traumas from full-contact sports have been linked to CTE. CTE has in turn been linked to a variety of behavioral and psychological symptoms and has been primarily characterized by brain degeneration.
All I can leave you with is protect your brains guys - they’re precious. A few too many bumps and your brain might shrink.
That is a bite-sized overview of the neuroscience of America’s favorite pastime and traumatic brain injuries. I hope that you enjoyed the episode and you learned something new! I’ve cited all my relevant sources and papers in the show notes and you should keep an eye out on Instagram for some cool figures I think are pertinent.
Please rate, review, and subscribe and if you have any questions, comments, concerns, queries, or complaints please email me at neuroscienceamateurhour@gmail.com or DM me at NeuroscienceAmateurHour on Instagram. This podcast is available on pretty much any platform I can think of so please recommend it to your friends and loved ones! Also if you have something you really want to learn about - please contact me and you’ll probably see an episode about it soon!
Happy researching! Hope to see you again soon!