“If you’d said to me,” says Alan Carson, a professor of neurology at the University of Edinburgh, “‘You could be the centre-forward for Manchester United, but you’d have an extra one in 100 chance of having Alzheimer’s when you reached 70,’ I’d be like, thank you, okay, so when’s kick-off?”
In recent years, there has been growing concern over the links between contact sport and dementia. The concern was first raised in the US, when scientists noticed in post-mortem examinations that some retired American football players had small-scale damage to tissues that was reminiscent of Alzheimer’s patients.
There was even a 2015 film starring Will Smith, Concussion, about Dr Bennet Omalu, a doctor who first called attention to the possibility. The National Football League ended up paying hundreds of millions of dollars in compensation to former players.
In the UK, similar fears were raised in 2016, when a group of doctors called for a ban on full-contact tackling in school rugby. And, of course, there has long been a worry over players heading the ball in football.
Jeff Astle, the former West Bromwich Albion and England player, died of dementia in 2002, aged just 59. A coroner ruled that he was killed by “industrial disease” – that is, his dementia was caused by his work. He was a powerful striker who scored a large number of headed goals.
Since then, a number of former footballers have been diagnosed with, or died of, dementia, and many of them have had that diagnosis linked to their careers, whether by the media or by coroners’ verdicts.
Both the World Cup-winning brothers Jack and Bobby Charlton were diagnosed – Jack died in 2020. Their England teammates Nobby Stiles, Peter Bonetti and Ray Wilson also had dementia, as did the Welsh internationals Keith Pontin and Alan Jarvis.
But what does the science say? Is football causing these cases, or is it coincidence? After all, people get dementia anyway – it could be that many or most of these players would have got dementia anyway. At the inquest into Pontin’s death, Cardiff City FC argued that his illness was not caused by his profession – were they right?
A growing body of evidence
I first wrote about this issue in 2016, and back then, despite the hype, I concluded that the evidence was not as strong as it could be.
There were lots of cases of dementia in sportspeople, and their brains were often found to have a particular kind of small-scale deterioration known as “chronic traumatic encephalopathy”, or CTE. CTE involves the buildup of an abnormal protein, “tau”, in the brain.
But for a long time, the evidence came from examining dead sportspeople’s brains. And on the whole, you only investigated a sportsperson’s brain if they had demonstrated symptoms of brain deterioration in life.
What we didn’t know was how common CTE was among people who hadn’t played contact sports, or among sportspeople who didn’t have symptoms of dementia. And epidemiological studies struggled to find increased risk of dementia among professional players.
Since then, though, says Carson, the evidence has moved on. The most important work, he says, has been by his fellow Scotsman Willie Stewart, a neuroscientist at the University of Glasgow, and his lab.
The FIELD study looked at dementia rates among former professional footballers, but – importantly – dividing it up by the positions they played in: goalkeeper, defender, midfielder, striker. Then it compared their dementia risk to people of similar backgrounds but who hadn’t played professional sports.
It found that outfield players had a noticeably higher risk of dementia than non-sportspeople, but that goalkeepers – who head the ball less than their teammates – had a risk that, according to standard statistical rules, was indistinguishable from zero. Defenders had the highest risks.
Carson, who had been worried about the shortage of evidence when I spoke to him in 2017, said that Stewart’s research “was high quality, certainly enough to influence me. I’d now accept that contact sports are associated with an increased risk of dementia.”
Stewart himself adds that the FIELD study’s findings “have since been corroborated by a study of French professional footballers which … shows roughly the same outcome.” Carson agrees that it matches other research, including that into American footballers.
How big an effect?
Roughly speaking, the FIELD study found that a footballer has between three and five times as much chance of being diagnosed with dementia as someone of similar background.
That sounds worrying, and it is, but it’s worth adding some caveats. First, although a three- or five-fold increase in risk sounds bad, dementia is mercifully pretty rare, at least until later life. A small number times three might still be a small number: if playing football increased your risk of dementia from one in 3 million to one in a million, would it matter?
In the under-65s, it almost is that rare. “You’d probably see about one extra case in the entire population playing professional sport,” says Carson. “Even at age 70, a tripling of the risk would mean roughly one extra case in every 100 people. It’s only above age 80 that it really starts to play out in big numbers.”
Stewart agrees with these numbers, but is keen to emphasise that the risk increase is real and important. “Forty-five-year-old former footballers are about 3.5 times more likely to die of neurodegenerative disease than expected,” he says, “as are 85-year-old former footballers. It’s just that deaths from neurodegenerative disease in the general population at age 45 are rare, while deaths at 85 are more common. They’re still important numbers.”
More from Long Reads
Of course influencers are out of touch in the cost of living crisis, it’s what we want of them18 June, 2022
Sanction 100,000 members of Russian elite to pressure Putin into ending war, experts warn17 June, 2022
I studied the psychology of secrets – then my dad told me what the family had kept from me17 June, 2022Second, there are lots of things that are associated with a similar increase in dementia risk. People who don’t go to university, for instance, are also about three times as likely to develop dementia as those who do, even when you take into account how well-off they are or lifestyle differences like smoking.
It’s also important to be clear that playing sport has health benefits. “Sport is associated with a 50 per cent reduction in all-cause mortality up to age 70,” says Carson. “If you want to halve your chances of dying before 70, playing contact sport will do it.”
Again, Stewart agrees with the point, but emphasises that once you get past 70, footballers are at greater risk. “Overall mortality is slightly better in former footballers,” says Stewart, “translating to about a two-year increase in life expectancy. But that risk is age-dependent: mortality in footballers is very much lower in younger ages, higher in older ages.”
We’re talking about heading the ball, not concussion
A slightly confusing point is that this discussion is about repeated, relatively minor impacts, like heading the ball. But a lot of the discourse about sport and head injury risk is about concussions – clashes of the head leading to dizziness and confusion. They’re very different things.
“The evidence that single, high-grade traumatic brain injury is linked to dementia is distinctly questionable,” says Carson. “But there is a separate issue, which is that if you’ve had a concussive injury, you’re at dramatically increased risk of getting a second injury in the near future, within 48 to 72 hours.” For most concussive injuries, your brain can recover reasonably well, given a few days.
The concern with “second impact syndrome”, as this is called, is not that you might have an increased risk of dementia 30 years down the line. It’s that “You might have a dramatically poor outcome from that second injury,” as Carson puts it, which might mean severe and permanent brain damage or even death.
“It’s a separate equation,” he says, “And I don’t think you’d find anyone in the medical profession who’d have a view other than getting people off and keeping them away from play, and having a strict implementation of head injury protocols.”
That’s especially true at school or amateur level. “It’s not always straightforward to diagnose concussion,” says Carson. “But the idea that the under-14s star centre-forward needs to stay on against the rival school [after a concussion] is bonkers: the kid’s at risk of death. ‘If in doubt, sit them out’ – if you’re even doing a head-injury assessment, they should be off the park.”
Maybe at elite level, where the stakes are higher, it might make sense to assess someone and then send them back on if they’re not concussed. But even then, “I’d favour having a third-party assessment. It’s hard if you’re the team doctor, and you have all the pressures of the team’s needs. If you’re the Liverpool doctor going up against Jurgen Klopp, that seems a very difficult position: it should be a third-party doctor.”
What should we do?
The risks of head trauma from playing contact sports like football appear to be real. But it’s also worth being clear that the benefits of sport are real, too.
“There are benefits from sport,” says Stewart. “Reduced cardiovascular deaths, better mental health outcomes, but also a standout risk of neurodegenerative disease. The goal is to retain the benefits but mitigate or eliminate the risk. In theory, this form of dementia could be entirely preventable.”
Carson says that he and Stewart, who have known each other and debated each other for years on the topic, both agree on the increased risk. They might disagree somewhat on how much people should worry about it, but “We basically agree it’s sensible to do minor interventions – maybe stop multiple repeated heading in football training, but absolute bans on heading are probably excessive given the risk and the evidence.”
For professional clubs, meanwhile, he says “If football wants to take this seriously, I’d focus on every other aspect of lifestyle and preparation for life after football.”
In particular, he’d try to find ways of encouraging former players back into the education system, because university education is protective against dementia, probably through getting people into cognitively demanding work.
Stewart has simple advice for parents: “They should still encourage their children to participate in sport, but ask questions of the coaches and teachers about their approach to concussion management and contact and heading training. If they don’t appear to be aware of the need to limit contact, go and find another club.”
Importantly, says Carson, we shouldn’t let this concern about dementia put people off sport. These risks are real, but the FIELD study looked at professionals who play for hours a day, and the risk was greatest among those with the longest careers: it will be much lower for casual players who are just doing it for fun and to keep fit.
“Organised team sports are remarkably good for kids and teach them a lot of life skills,” he says. “I’d have no hesitation at all at pushing my kids to participate.” Even if they don’t end up as the centre-forward for Man United.
from Football | News and analysis from the Premier League and beyond | iNews https://ift.tt/CbAYWST
Post a Comment