All the NFL has to do is wait
In 1928, Dr Harrison Martland, a retired Lt. Col. in the US army's medical services cum county pathologist for Essex County, New Jersey released a paper proposing a newly discovered form of dementia. He called this dementia 'punch-drunk syndrome' and claimed it was most likely a non-congenital variant of Parkinson's Disease. The name came from the vernacular of the subjects Dr Martland observed the disease in: a cohort of professional boxers, each with more than 50 fights. In the world of professional boxing, being 'punch-drunk' referred to the symptoms of disorientation, unsteady gait, tremors, memory issues, and mental fog one experienced as a result of a concussion. Dr Martland observed that a significant number of boxers exhibited permanent low-level concussion symptoms in constellation with emotional dysregulation, suicidal ideation, and poor impulse control. Martland proposed that the repeated traumatic brain injuries suffered by boxers during the course of a boxing match were causing persistent brain damage and inducing early-onset dementia in elite boxers, but did not bother evaluating athletes in other sports or the general population.
Until 1948, it was assumed that punch-drunk syndrome was a problem unique to explicit combat sports like boxing and that certain players were prone to the disease and others were effectively immune to it. The first of these myths was dispelled in 1949, when neurologist MacDonald Critchley released the paper “Punch-drunk syndromes: the chronic traumatic encephalopathy of boxers,” and the second in 2005 with Bennet Omalu's paper “Chronic traumatic encephalopathy in a national football league player.” As it turned out, any sufficient and repeated disturbance to the position of the brain in a person's skull causes the disease, by then renamed to the more neutral 'CTE.'
The development of CTE does not require, as Critchley and Martland believed, direct blows to the head nor are some people particularly resistant to it. The brain sits in your skull in more or less a pool of cerebrospinal fluid (CSF). It is not secured in place in any way other than by connection to the spinal cord and small amounts of connective tissue. Any time your head snaps forward or back, the brain sloshes in place and risks damage against the hard surface of the skull's interior. This phenomenon is obvious when a concussion occurs, in which the brain strikes the surface of the skull hard enough to cause temporary disorientation, but it also happens pretty much any time you are struck hard enough on the head that it hurts, any time that you are brought to a sudden stop while moving very fast, and any time you are exposed to a shockwave (e.g. by proximity to a very loud noise or explosion). Whenever this happens, a few things occur that contribute to the risk of developing CTE. The first is ruptures in the very tiny blood vessels that lace your brain. The rupturing of these vessels damages nearby brain cells, often permanently destroying them. Secondly, the energy introduced by the blow causes the spontaneous misfolding of an important protein called the Tau protein. Tau proteins are critical to the healthy functioning of brain tissue, and the presence of misfolded tau proteins causes the breakdown of nearby brain cells. In patients with advanced CTE, disordered tau proteins accumulate on the surfaces of the brain and cause the brain to begin breaking down from the outside inward. It is important to note that this process is not determined by genetics, it is a matter of simple biochemistry. Anyone who sustains enough hits to the head can develop CTE, as there is no way to avoid the blood vessel ruptures or tau protein misfolds that cause the disease except by not being hit in the head.
Why didn't we notice CTE until 1928?
Everyone will experience the brain injuries responsible for CTE to various degrees throughout their life, however the threshold of ruptured brain blood vessels combined with the critical mass of misfolded tau proteins is very high. You would have to take thousands of sub-concussive blows to the head or suffer more than a few concussions before you would begin to feel symptoms of lower stages of the disease. This belies the reason for CTE's relatively recent discovery compared to the wider family of dementia. Simply put: men* were not getting hit in the head enough for any well-known person to have the disease until the professionalization of sports.
Before the 20th century, sport was not really a professional affair. There were few, if any, famous paid athletes. Many leagues, including the top level leagues in soccer, rugby, and gridiron football prohibited the direct payment of players. Instead, professional athletes relied entirely on endorsement deals and under-the-table compensation. Being a professional athlete before the 1920s was not a glamorous job, and athletes earned well below average salaries. The most popular sport in Canada and the United States during the 19th century – gridiron football – was played mainly at the collegiate level, with famous athletes graduating into normal jobs after brief careers. The NFL, which sanctioned direct payment of players, would not exist until 1920 and the Canadian Football leagues would not endorse professionalization until well into the 1940s (although by 1920 most successful clubs were paying their players anyway). Boxing, the sport in which CTE was first identified, did not professionalize until 1891.
The amount of trauma you would have to experience to develop severe CTE is so great that until sports was professionalized, the majority of athletes (but not necessarily all athletes, as we will discuss) were not playing long enough to develop it. With professionalization came optimization. Not only did the careers of contact sport athletes balloon in length with the creeping in of professionalization, but so did the intensity of athletic training. It wasn't just that sporting clubs and boxing gyms want to extract the greatest value from the athletes they were now paying, but the athletes themselves were increasingly personally and socially incentivized to sacrifice absolutely everything in pursuit of making it to the top. By the time the first NFL player was officially diagnosed with CTE during an autopsy in 2005, American Football had transitioned from a casual sport to a national lottery ticket. The implicit promise of professional sports is this: if you are genetically blessed and work hard enough, you will catapult your family to extreme heights of wealth. In a system as brutally unequal as ours, millions of people are going to try that path knowing they have no other way to escape the indignity of proletarianization, even if it means becoming mentally and physically disabled before age 30.
* I use the word 'men' here deliberately. In fact, a shocking number of non-athletic women develop CTE. Twice as many women suffer from CTE relative to men (5% of men vs 10% of women) due to head trauma sustained as a result of domestic violence. CTE is not a new phenomenon, measurement of it is.
CTE and Football
On July 29th, 2025 former high school football player Shane Tamura opened fire in an office building hosting the headquarters of the NFL before turning the gun on himself, shooting himself in the chest to preserve his brain for study. According to Tamura, he had played 4 years of football at the JV and Varsity levels as a running back*, which he believed at left him with severe CTE. He claimed that the NFL had deliberately curated the competitive environment in high school football that does not adequately inform children of the risks of football while doing nothing to mitigate the likelihood of traumatic brain injury. What makes Tamura's claims particularly resonant is not just that he was found to actually have CTE in a subsequent autopsy completed earlier this week, but that he is not the first NFL player to develop CTE and become homocidally violent. Most famously, New England Patriots Tight End Aaron Hernandez was convicted of murder, killed himself, and was found to have Stage 3 CTE at age 27 during his autopsy.
Tamura was both right and wrong. In truth, Tamura was unlucky. Football certainly dramatically increases your risks of CTE even at the high school level, but only 20% of former high school players who play for all 4 years of eligibility develop the disease, which is 4 times the level of the general population of men but is hardly a guaranteed outcome. He is correct, however, that he was probably not made aware of the risks and the NFL is at fault for that. The NFL is very involved in amateur football at all levels, and could easily mandate stricter education on risks and strict eligibility criteria such as the immediate ending of an amateur player's career after 1 concussion, e.g., but chooses not to. The NFL could discourage children from playing tackle football entirely as the CFL does – encouraging minors to play flag football instead, but doing so risks jeopardizing the future massive talent pool the NFL relies on to both sell tickets and maintain leverage over its players union (one of the weakest in American sports).
Unfortunately for the NFL, public knowledge of the risks that football poses to brain health has increased significantly since Omalu's case report in 2005, which does pose a risk to youth football. Informed parents are less likely to enroll their children in tackle football than before knowledge of CTE was common, and youth football enrollment has declined by ~6% in the US since the report was released.
* a position in gridiron football equivalent to a centre or fullback in rugby. Running backs are particularly vulnerable to injury, whether to the brain or otherwise. This is because of the specific role of the running back, who is tasked with punching the ball through the defensive line (one of the physically largest groups of players on the field), and the body type prioritized for the position (smaller players are typically put in this position due to their lower centre of gravity).
CTE and other sports
Sucks to be the NFL or whatever organization it is that is in charge of MMA nowadays, one supposes! As evidence mounts on how easy it is to get CTE from not just fighting but also football, it may appear that those sports are uniquely doomed. The NFL does not seem worried, though, and for good reason. The pendulum of evidence begins to swing in the other direction and all the NFL has to do is wait.
The reason why CTE was first noticed in boxing is that combat sports are uniquely violent. Football was the second sport to have a major crisis with CTE because it was simply next on the list of most violent sports, but as scientific interest in CTE has increased so has the evidence that the best athletes in basically every sport are getting it. The dam broke on this in 2020, when autopsies of Rugby and Australian Rules Football players found significant rates of CTE. Then, ice hockey, and even baseball and soccer were eventually found to significantly increase the risk of CTE. Football is bad for your brain, but not uniquely so. The NFL gambled that the whole CTE thing would blow over, and they are probably going to be proven right. As more and more sports are found to raise your risks of CTE, the risk sustained by football players will be washed away in a tide of noise. CTE, it turns out, has more to do with being a professional athlete than what sport that athlete happens to play, even if certain organizations have obfuscated the particular level of risk of their particular sport for their own benefits.
What should we be doing about CTE?
To be clear, I am not saying that football's risks are exaggerated in the aggregate. CTE is not the only potential risk from playing football. Famously, Calvin “Megatron” Johnson was left permanently unable to run after his retirement from the NFL, as he had sustained so many fractures in his lower legs that his ankles had fused from improper healing. All it takes is one bad play to be paralyzed or worse, even if you don't play long enough to raise your CTE risk. What I am saying, however, is that the specific threat of CTE will not kill football. You could make the argument that through their own actions, the NFL has caused thousands or even millions of people to suffer the effects of CTE and something should be done about this. But what?
The NFL's status as the world's most profitable sporting institution on Earth makes it nigh untouchable in the United States. Even attempts to regulate it without holding the NFL accountable for its role in all this are essentially impossible. Last year, the state legislature of California, the state in the union that is ruled by an unholy union of tech nerds and granola hippies and therefore should be the most amenable to shuttering football passed a bill restricting organized tackle football to people over the age of 12. The bill was vetoed and even if it hadn't been vetoed, it would've been swiftly struck down by the first court it was challenged in. I don't think there is anywhere in the United States with the political will to mandate a curtailment of the risks of American Football to the athletes who play it and I don't think any theoretical advocacy group would ever succeed in boosting that cause.
The fight to reduce the risk of CTE is further complicated by the fact that technically speaking, CTE can only be diagnosed in autopsy. Research is ongoing in making misfolded Tau proteins show up on PET scans, but as of now, there is no way to know if an amateur athlete needs to retire for the sake of their brain until they're already dead. Hopefully, the research advances on this to the point where conscientious athletes or their guardians can monitor their brain health and step out when the risks have become too great, but I'm not holding my breath (remember the economic incentives to ignore all this!)
Do not forget, though, that football is not the only game that gives you CTE. Even if football were to disappear from the Earth tomorrow, the only real answer to CTE is the end of professional sports itself. It was not sport as a past-time that has caused the rise of CTE in athletes, it is sports as a profession. The obsession with optimization and training incentivized by sports as the only realistic escape from grinding poverty for billions of people. Before the NFL and MMA and FIFA, people were playing street football, joining boxing gyms, and kicking soccer balls around in fields every once in a while without realistically risking CTE. Professionalization of sports is an inevitable result of capitalism. People enjoy playing and watching sports, thus it must be marketized and commodified. I leave you with the following advice: don't let your future kids play tackle football.
“Whatever,” to paraphrase Donald Trump, “I'll keep watching that garbage.”