New research into the impact of heading on brain function has found that just 20 ‘normal’ headers with a modern synthetic ball was enough to make most players fail a pitchside concussion test.

The study, which was carried out at the Liverpool Hope University and reinforces comparable recent research in Scotland and the United States, will intensify fears that football’s dementia crisis is directly linked to heading and not confined to a particular past era. 

Dawn Astle, who runs the Jeff Astle Foundation, has also told The Telegraph that her charity is being contacted increasingly by the families of professional players from the 1970s and 1980s – and that there has been no anecdotal decline in numbers since her father’s death in 2002.

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The new research further increases pressure on the domestic football authorities who, having introduced heading limits on children’s training, including a ban on those of a primary school age, have done nothing to change adult football.

This is despite landmark research which showed that former players were at an increased risk of dementia and repeated warnings that there was no evidence to support  a theory that the problem was confined to the pre-1970s era of the ‘old leather ball’.

Jake Ashton, a sports and exercise scientist, oversaw the Liverpool research which involved simply throwing up a ball to be headed by three sets of recreational players aged between 18 and 21. One set of players headed a ball that was inflated to the minimum legal recommendation, another to the highest ball pressure and the third group simply simulated the action of heading a ball. They each performed 20 headers and then immediately performed a series of cognitive tests, including the King-Devick concussion guide which is used in North America as an indicator of head trauma. “There was no real power behind the throws – but 80 per cent of the participants from the ‘hard’ and ‘soft’ ball group would have failed that test and been withdrawn from play,” said Ashton. “We were definitely surprised. To find that affect from that little protocol was quite worrying.” 

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As well as the signs of concussion, the research found a decline in ‘verbal and spatial working memory’ in the players by as much as 20 per cent. The findings have been published this week in the Science and Medicine in Football Journal and Ashton has spoken with the Football Association about other potential future areas for research.

A separate study by the University of Stirling also found a reduction in memory performance after players headed a football 20 times that was delivered with the pace and power of a corner-kick. Memory function, which was reduced by between 41 and 67%, did return to normal 24 hours later. Dr Willie Stewart, the Glasgow neuropathologist whose landmark research established the link between dementia and football, has been advocating restrictions on adult heading in training. In light of the research, this would involve a limit of 20 headers per session and a break of at least 48 hours between sessions.

Other studies have identified brain proteins in a players’ blood after a single training session of headers while brain scans of footballers have shown the greatest change in those who head the most.

Research of amateur footballers in America has also this year reported an association between high amounts of heading and worsening verbal memory performance, especially among those with a particular gene.

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This study, which was conducted by the Albert Einstein College of Medicine in New York and led by Dr Michael Lipton, focused on 352 amateur players, who were on average 23 and had been playing football regularly for more than five years, and found no difference in a verbal memory test for those players who were not exposed to frequent heading.

The research also found a potential genetic factor which is present in around 10-15% of the population. “Accumulated heading over a period of time, whether it’s two weeks or a year, especially in those with high levels of heading exposure, is a very strong predictor of worse performance on tasks, most robustly on this memory task,” said Dr Lipton. The Albert Einstein College of Medicine previously also found that amateur players who headed the ball frequently were three times more likely to have concussive symptoms. “Our key finding is that heading is by no means innocuous and, at least in those who do a lot of it, is commonly associated with symptomatic events, even probable concussive events," said Lipton.

As well as limits in heading during training for adults, Ashton has suggested the use of sponge balls during children’s sessions. Dr Stewart’s study showed that former professional players were 3.5 times more likely to die of dementia, including a five-fold risk of Alzheimer’s and a four times increased risk of motor neurone disease. Although a link has been found between brain trauma and dementia, the precise cause of the increased risk in football has not been established.

Players’ union FIFPro also want temporary concussions substitutes and campaigners are now urging Fifa, football’s world governing body, to take a leadership role in this issue.

A spokesperson for Fifa said that “protecting the health of players is – and will remain – a top priority in developing the game” and that an advisory group had been formed to advise on changes to the Laws of the Game.