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Is CTE even a diagnosable disease?

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A look at the research done on Chronic Traumatic Encephalopathy and questions over if it is actually a diagnosable disease for athletes in sports with high brain trauma risk.

Chris Hyde

This is a guest post by The Sports Skeptic @sportskeptic on Twitter.

Growing up as a sports fan in the Texas panhandle, I was always fascinated by local athletes who made it big on the national stage. Maurice Cheeks (basketball) and Donny Anderson (football) were a couple of those athletes. However, I can’t think of any athlete from the Texas Panhandle who made more of an impact internationally than World Champion boxer Terry Norris.

Terry was just a couple of years older than me and I first heard of him playing baseball. In fact, if it wasn’t for an unfortunate on field incident incited by a racial slur that resulted in three opposing players being hospitalized by Norris’ hands, Norris may have chosen baseball over boxing. However, Norris did choose boxing and was electric to watch. Norris finished with a 47-9 career record and once held both the IBF and WBC light middleweight titles. Being a fan for the better part of two decades, it was with great sadness that I read that Norris had been diagnosed with Chronic traumatic encephalopathy or CTE.

Years ago, CTE was known as Dementia Pugilistica because of its prevalence amongst boxers. Boxers who were called "punch-drunk" were assumed to have this "disease" because of their behavior. More recently, we have seen other sports take notice of CTE. On August 30 of last year, the National Football League reached a $765 million settlement with the former NFL players over head injuries. This was primarily driven by 33 former players who were diagnosed with CTE post mortem and recently retired players like Tony Dorsett and Bernie Kosar who were diagnosed with CTE symptoms. In January, though, a US District judge rejected the settlement due to the large number of played not named in the lawsuit not being fairly compensated.

With this amount of money and the health of its athletes at stake, it seems like a no-brainer for sports like boxing, MMA, football and hockey to put more protection in place for its athletes.

Or is it?

Despite these headlines, there is much debate within the scientific and medical communities surrounding virtually everything about CTE including its symptoms, its diagnosis and even its existence. In addition, there many statistical conundrums that fly in the face of this damning narrative.

* Symptoms

CTE is virtually impossible to treat and/or diagnose because it has no defined clinical diagnostic criteria until the brain is examined port-mortem. Similar to other subjective syndromes and disorders like ADHD, CTE is a hodgepodge of medicine, hype, and fear.

The list of symptoms provided by a team led on one of the world’s leading experts on CTE, Boston College’s Ann McKee, in their January 2013 paper "The spectrum of disease in chronic traumatic encephalopathy" is incredibly broad and are commonly observed in normal healthy individuals to those seen in individuals with neurological diseases. Some of those symptoms included are:

  • headache
  • depression
  • impulsivity
  • explosivity
  • aggression
  • attentional impairments
  • paranoia
  • executive impairments
  • memory loss
  • language impairment
  • visuospatial impairment

The problem with such a broad list of symptoms is that without any specific objective diagnosis, the list is virtually meaningless because each of these symptoms or any combination of them could be indicators of numerous other neurological diseases or nothing serious at all. However, if you have any of these symptoms and are a former athlete, then its likely you would be told you have CTE.


So how do we know our sports heroes like Terry Norris and Tony Dorsett have CTE? The bottom line is that we don’t. All we know is that a doctor has examined them and has seen them exhibit some of the symptoms listed above. Those doctors, factoring in the athletic pasts of their patients, have concluded that CTE is the likely cause of the symptoms. But definitive proof? That can only come from an examination of the brain post-mortem.

And what does that examination of the brain tell us? It has to be that it clearly shows CTE, correct? Not exactly.

The primary marker for CTE is the accumulation of the Tau Protein in brain cells. Tau proteins are proteins that stabilize microtubules in our brains. However, when these proteins are defective, they can no longer stabilize microtubules properly which can lead to dementia or Alzheimers. This presents a problem for any CTE diagnosis post mortem as well. If the primary marker for Alzheimer’s and dementia is the same for CTE as it is other neurological disorders, then how do we do know an individual has CTE and not something else?

Additionally, there is debate within the medical community what the buildup of these proteins mean. According to a study published in the journal Neuropsychology Review written by Loyola University Medical Center clinical neuropsychologist Christopher Randolph, PhD and Stella Karantzoulis, PhD, of New York University School of Medicine found that former football players' Tau protein buildup wasn’t significantly different than others who have Alzheimer’s. "Different neurodegenerative diseases have very different cognitive profiles," Randolph says. This could mean that CTE shouldn’t be classified as its own disorder/diease just yet. Neurological diseases like Huntington's, Alzheimer's and Progressive supranuclear palsy (PST) all have specific patterns of degeneration they cause. If CTE has one of these patterns, it hasn’t been discovered yet.

As Randolph told Popular Science, ""The question really is, does having tau in your brain mean anything?" . Right now, all we have is a correlation between some players who have exhibited symptoms during their life and a documented tau buildup in their brain post-mortem. This could mean something or it could be a false lead. One key to good science is finding causation along with correlation. Without causation, it’s just a guess.

Another study on CTE in April 2013 titled "What is the evidence for chronic concussion-related changes in retired athletes: behavioral, pathological and clinical outcomes?" led by Paul McCrory who is an Associate Professor at the Florey Institute of Neuroscience and Mental Health had this to say about the evidence regarding CTE:

"At present, there are no published epidemiological, cross-sectional or prospective studies relating to modern CTE. Owing to the nature of the published studies, being case reports or pathological case series, it is not possible to determine the causality or risk factors with any certainty. As such, the speculation that repeated concussion or sub-concussive impacts cause CTE remains unproven. The extent to which age-related changes, psychiatric or mental health illness, alcohol/drug use or coexisting dementing illnesses contribute to this process is largely unaccounted for in the published literature."


Let’s also look at some data that seems unusual if CTE is truly real:

* No sport has more concussions than boxing, but the rate of CTE diagnosis in boxer is slightly less or the same as NFL players or military personnel.

* Suicide is more prevalent in hockey players, NFL players and military personnel than in boxers.

* The sport worldwide with the most players and consequently the biggest data points is Soccer. However, soccer players have high concussion rates yet very low rates of CTE.

* NFL players live longer than men in the general population


Randolph also told Popular Science, "There's not sufficient evidence to justify the assumption that CTE exists at this point." That seems to be a bold statement that is against everything published in the mainstream media, but let’s recap the facts:

* CTE has a broad list of symtoms that mirror many other diagnoses

* CTE can only be diagnosed post-mortem through the buildup of tau proteins

* There is no evidence that repeated concussions cause CTE

* The tau buildup in brains of CTE patients mirror other neurological diseases

* There is no evidence of causation between tau proteins and CTE

* Retired NFL players live longer than the average population

With those facts in hand, the public should be very skeptical of any diagnosis that a living athlete has CTE but they should also be skeptical when anyone makes the claim that CTE is well defined and is confirmed as a disease.


As Randolph and Karantzoulis concluded their study, "One cannot deny that boxing and other contact sports can potentially result in some type of injury to the brain. There currently are no carefully controlled data, however, to indicate a definitive association between sport-related concussion and increased risk for late-life cognitive and neuropsychiatric impairment of any form."

No one likes to hear news that one of their heroes is sick or is struggling like Terry Norris or Tony Dorsett, but it is also important for the sports community not to fall for all of the hype surrounding CTE. It could be much more damaging to Norris or Dorsett if they have another neurological disease but have been diagnosed with CTE simply because of their sporting pasts. Much more research needs to be done to confirm not just CTE’s existence but its ties to sports as a whole. What is most important, though, is that these leagues embrace and fund research to make their sports as safe as possible but not to jump on the bandwagon of hype, fear and hysteria that is CTE. At least, until there is some evidence.