Back in 1970, Jeff Astle played for England at the FIFA World Cup. In 2002, after suffering with a dementia-type brain disease for a number of years, he died at his daughter’s home, aged just 59.
Later analysis in 2014 of Astle’s brain revealed he’d suffered from chronic traumatic encephalopathy (CTE), a brain disease often seen in boxers. The neurosurgeon who performed the examination, Dr Willie Stewart, concluded that much like powerful blows to boxers’ heads, Astle’s repeated heading of the ball had caused his CTE.
Now, Stewart has been part of a team that has revealed that former professional footballers are 5 times more likely to have a dementia-type illness, and 3.5 times more likely to die from it than members of the general public.
Since the findings were published in October, former players and football fans have called for a change in the rules around head injuries and heading the ball. As of 24 February 2020, the Scottish Football Association has banned children under 12 heading the ball. But does the science support this?
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Stewart’s study looked at data from over 7,000 former professional players and 23,000 controls from the general population, matched on the basis of sex, age, and socioeconomic class. The findings were based on mortality rates and prescriptions of drugs for dementia symptoms.
“Out of those 1,180 footballers in our study who died, 222 had died of neurodegenerative disease-related cause. 228 members out of the control group [of 23,000 people] died of a neurodegenerative disease,” explains Stewart.
“Considering there had been 3 times as many people in the control group, we expected to see 3 times the number of deaths.”
The study set out to determine whether professional footballers are at greater risk of getting and dying from dementia. But within this, there’s another factor at play: was heading the ball or collisions between players to blame?
“That’s very difficult to determine with the data we had,” says Stewart. “We don’t know how many concussions or head impacts a player had. It’s just not documented.”
To attempt to tease out a conclusion from the data, the team compared outfield players to goalkeepers. “Although we saw a slightly lower mortality in goalkeepers than in outfield players, statistically we just couldn’t prove it wasn’t chance,” says Stewart.
“But when we looked at prescriptions, goalkeepers were less than half as likely to have been prescribed a dementia drug, which would imply that goalkeepers’ rates of dementia were about half that of outfield players.”
Currently, the research that’s looked at the pathology of dementia in footballers and other sports suggests to Stewart that exposure to head injury is the most likely risk factor. There have been suggestions that the heightened numbers could be related to the amount of drugs or alcohol that professional players have been exposed to.
“These arguments don’t stack up,” argues Stewart. “We’re talking about something that is a common agent to boxers, American footballers, rugby players, footballers, wrestlers, victims of domestic violence, road traffic accidents… there isn’t one common risk factor that you can draw through all of these other than head injury.”
The brain after heading
So how exactly does head impact and concussion lead to dementia? Dr Magdalena Ietswaart, senior lecturer in psychology at the University of Stirling, has spent the last few years finding out.
In 2016, Ietswaart and her team discovered that there are detectable changes in the brain after heading the ball just 20 times. “We know that there is a link between traumatic brain damage, such as concussion, and long-term damage,” says Ietswaart.
To measure how brain chemistry is affected by heading, Ietswaart and her team looked at how long it took for a signal to travel from the brain to, say, a muscle in the leg. The team found that the communication between the brain and muscle slowed after just 1 session of practice headers.
“We also found effects on memory after heading the ball, which is interesting,” says Ietswaart. Scientists know that a healthy brain chemistry is needed for processes of plasticity (the ability of the brain to change and adapt), which is essential for things like learning and memory.
The participants’ inhibited brain-to-muscle communication levels returned to normal after 24 hours, but Ietswaart warns that the long-term consequences remain unknown.
The study faced criticism from some quarters. “People have said to me that footballers head the ball [during a game] much less now, but there is no science to say that less heading is then going to be fine.” says Ietswaart.
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“Similarly, people said that it was ‘extreme’ that we had people heading the ball 20 times. But that was the number of times that local football players would practice heading the ball during training. And there’s nothing to say that if you just head the ball 10 times, everything is fine.”
One concern that both Ietswaart and Stewart share is when people blame the old, leather-style footballs of bygone days, they’ll think the new plastic ball is safer. In fact, Ietswaart’s 2016 study was done with the modern ball.
“We certainly have no evidence whatsoever to say that anything that has happened in the game in the last 10 years, 20 years, or longer, will have changed the risk of neurodegenerative disease for footballers,” says Stewart.
“My concern would be that if we assume – with no evidence or data to back that up – that technology in the modern game has changed and that there’s no risk any more, we may be putting our footballers at risk of carrying on with a high chance of getting the disease.”
According to Stewart, there needs to be better management of head injuries in the modern game. “In that regard, football is woefully inadequate. If you look at rugby, for instance, if there is a suspected head injury the player goes off and is assessed for up to 10 minutes at the side of the park.
“That doesn’t happen in football. There might be a passing few minutes allowed on-field for an assessment, but it’s nothing like adequate. It’s the same injury. But it’s being managed in quite different ways.”
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Ban or no ban?
With regards to a ban, both researchers are reluctant to call it a decision informed by science. “The truth is we don’t know whether a developing brain is more at risk,” says Ietswaart.
“We do now know that the brain is still under construction until the age of 23. Particularly between the ages of 14 and 23, the frontal lobes in the brain get a complete rewiring. Nobody wants to know that a player in their prime still has a developing brain.”
“We’ve been doing some work looking across youth groups, and it turns out that younger kids – under 14s – barely, if ever, head the ball during a match,” comments Stewart. “Are we training kids during the week by repetitively hitting the ball off the head, for that one rare occasion where they might head the ball during a match?
“I don’t think they’re losing anything from the game to say children will not head the ball any more. But going further than that into adults and professionals… we’ll need to get some science and take that forward before making decisions on heading.”