A groundbreaking new paper, written partly in New Zealand, confirming the link between CTE and recurrent head injuries should be a game changer for the sport…or not?
IIn the wild and sometimes confusing encounter at last night’s Bledisloe Cup in Melbourne, All Black teammates David Havili and Sam Cane butted heads when attempting to tackle the same player. Both subsequently failed due to head injury evaluation and were removed from the game, which was won by the All Blacks 39-37.
Cane has suffered many concussions throughout his career. Last night was just another reminder of the random brutality of modern gladiator play. A little over a month ago there was another reminder. When the story fell, the reaction was almost instantaneous.
“Huge moment,” an ex-All Black told me. Similar messages ran through a loose collection of former players and their families – those dealing with diagnoses of early-onset dementia.
The story claimed that researchers had found “conclusive evidence” that repetitive head injuries (RHIs) caused chronic traumatic encephalopathy (CTE). A cross-university paper, authored by some of the world’s most respected neuroscientists, including three from New Zealand, and with Harvard imprimatur no less, found that the connection was definite.
“After reviewing the medical literature on [repetitive head injuries] and CTE… we have highest confidence in the conclusion that RHI causes CTE. We encourage the medical, scientific, and public health communities to act now on the premise of causality and take immediate action to prevent CTE, minimize risk, and develop therapeutics to slow or stop disease progression.” wrote the authors, who also included New Zealanders Sir Richard Faull, Helen Murray and Maurice Curtis, Head of Anatomy and Medical Imaging at the University of Auckland.
The Twitterverse jumped on board.
In press calls that day, Dr. Chris Nowinski, head of the Concussion Legacy Foundation: “Sports governing bodies should recognize that headbutts cause CTE and they should not mislead the public about CTE causes while athletes are dying and families are being devastated by this terrible disease.”
It felt like a turning point for the sport, its Big Tobacco = Lung Cancer moment. But instead, the reaction has been lukewarm in the medical science community and less than lukewarm at Big Sport.
CCritics say the paper’s conclusions are disingenuous because the relationship between CTE pathology and outcomes has yet to be established and that research has used the Bradford Hill criteria to determine the link, which are a handy set of broad brushes , but cannot draw the full picture.
One who thinks the compound has been oversold is world-leading biomechanist Patria Hume of AUT.
“I believe in the precautionary principle and from a biomechanical perspective, I fail to see how damaging your brain is in any way good for you in the short or long term. However, when it comes to whether there is strong evidence of cause and effect, as a scientist I have to say that there is none yet,” she says.
“It’s good that these issues are out there and we’re discussing them, but unfortunately in terms of causality, I just don’t see any evidence.”
Hume says that Bradford Hill’s work is, on the whole, a strong work, but in discussions with other people in the field, their problem is the summary, which jumps too far from the content of the work.
She says another work by Murray, a former New Zealand ice hockey captain turned neuroscientist, has done a fantastic job of highlighting the gaps in CTE knowledge as it relates to the sport. Murray’s summary states that we “need more comparative studies that examine a wide range of pathologies and how they differ between CTE, Alzheimer’s disease and normal aging.”
Curtis, one of the paper’s authors, says the Bradford Hill criteria measure eight different factors, including strength of association (in this case between RHIs and CTE), consistency across studies, specificity, plausibility, coherence, and ability to models to replicate themselves in animal experiments.
“It’s not like there’s a magic number [where correlation turns to causation]but there is strong evidence for all eight,” he says, citing 15 years of intensive studies on CTE, which he says has a distinctly different pathology from other neurodegenerative diseases like Parkinson’s and Alzheimer’s.
“We don’t just see this in a brain bank. This is not just the work of a neurologist. It doesn’t just happen in one sport. We see this in brain banks around the world.”
Hume’s call for caution in assessing causality between sports injuries and CTE is not new. A widely cited Lancet article written by renowned neuroscientist Dr. Willie Stewart, 2019, notes that “contrary to popular belief, the clinical syndrome of CTE has not yet been fully defined, its prevalence is unknown, and the neuropathologic diagnostic criteria are no longer than preliminary”. It warned of the potentially “dark” consequences of misrepresenting CTE for people who may have treatable conditions but are led to believe they are doomed to a life of neurodegeneration.
On the other side of the coin is the potentially more compelling argument that failure to recognize the obvious — that RHIs in sport can lead to brain disease — and Big Sport’s willingness to hide behind the cloaks of scientific method are likely contributing factors will cause hundreds and possibly thousands of unnecessary deaths.
It feeds into the narrative that Big Sport now plays the role of Big Tobacco, which exploited the “uncertainty” of the scientific method to flood the market with junk science and obfuscation for 30 years.
Lead New Zealand rugby scientist Ken Quarrie says this is not the case with rugby. He says while Big Tobacco deliberately deceived, Rugby assumed there was a compelling connection.
All Black David Havili is treated for a head injury during the first Bledisloe Cup test in Melbourne (Photo: Kelly Defina/Getty Images)
“We want to know and understand what the evidence is,” he said. “We recognize that there will be uncertainty with claims of causality related to a new health condition and that there will likely be controversy about what action should be taken as people have different views on the scope and quality of the Evidence have in relation to risk management.
“NZ Rugby will continue to act in accordance with the best evidence available and our general approach is to play it safe.”
Quarrie says the research he conducts as an organization aims to answer the question of what impact playing rugby at a high level has on long-term health.
“Studying neurodegenerative disease rates among ex-gamers compared to the wider population is an integral part of this,” he says.
TThe timing of the application of the Bradford Hill Criteria for Causation to Repetitive Head Impacts and Chronic Traumatic Encephalopathy, the paper in question, is important as it comes against the backdrop of a class action lawsuit brought by former players against World Rugby and several national unions, and the instability within those influential Concussion in Sport Group (CISG).
For years, much of Big Sport – a collective term for large multi-billion dollar sporting bodies such as Fifa, the IOC, the NFL and World Rugby – has happily accepted the findings of the CISG, whose consensus statement has refused to establish a definitive link between RHIs and CTE.
That group has been rocked, however, and some would argue it was discredited after its leader, Paul McCrory, was forced to resign over a plagiarism scandal (his work is also credited with the AFL, for which he served as a medical adviser, and the Australian investigates regulatory authority for naturopaths).
The group has not been able to meet during the pandemic but will do so again next month in Amsterdam. It is under pressure to flesh out its consensus statement on the possible long-term consequences of head injuries in athletes.
At the same time, World Rugby, Rugby Football Union and Wales Rugby are facing a class action lawsuit from a number of former players, including All Blacks propsman Carl Hayman and England World Cup winner Steve Thompson, who argue they were inadequate in the face of the dangers of recurrent head injuries be warned or protected.
Asked if contact sports are now facing a public health crisis, Maurice Curtis says he’s reluctant to use the term, but adds: “I don’t want to shy away from the fact that this is a serious matter”.
While NZR’s risk exposure is mitigated through ACC legislation and its No-Fault program, if CTE is determined to be an occupational disease, it will have a significant impact on sport around the world in terms of safety obligations at work.
“This isn’t about bashing any sport,” says Curtis. “The goal is to provide information and research that will help identify and reduce the problems.
“The last thing a 55-year-old ex-rugby player who may have consumed alcohol … and who has a brain disease needs to hear is that he caused it himself,” he continues. “It’s about helping people live the best life possible.
“We don’t want to ‘stop’ anything, because there are enormous benefits to doing sport.”
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