Heading a football just 20 times may lead to reduced brain function, a new study claims, following increasing concerns that footballers are at a higher risk of dementia.
UK researchers analysed the cognitive function – including memory and mental ability – of footballers before and after 20 headers.
They found working memory, which allows the brain to briefly hold new information while it's needed in the short term, declined by 20 per cent.
The vast majority of participants who headed the ball (80 per cent) also showed potential signs of concussion – temporary injury to the brain.
Calls for the links between dementia and football to be conclusively investigated have increased following the death of 1966 World Cup hero Nobby Stiles last month, who had advanced dementia.
His England colleague Sir Bobby Charlton was also recently diagnosed with the condition, which is associated with an ongoing decline of brain function.
Sir Geoff Hurst, an England teammate of both players, said this week that a total ban on children in the UK heading footballs would be 'a sensible suggestion'.
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Football has faced calls to restrict heading until the links with dementia are fully established. Pictured, Dara O'Shea of West Bromwich Albion wins a header over Pierre-Emile Hoejbjerg of Tottenham Hotspur on November 8, 2020
'Our results are both surprising and concerning,' said Jake Ashton, a postgraduate research student at Liverpool Hope University, where the new heading experiments was conducted.
'With the cognitive tests, there was a significant reduction in verbal and spatial working memory.
'While more research is needed, there may also be a need to put measures in place to limit heading during football training sessions, in all ages.
'The impacts of using a harder ball should also not be ignored.'
Children under the age of 12 are already banned from heading footballs in training in England, Scotland and Northern Ireland, and under-18s can only head the ball a restricted amount of times in training.
Ashton is now calling for sponge balls to be used during children's training sessions and for referees at grassroots levels to measure the ball pressure before match kick offs.
Stiles died in October this year at the age of 78 after a battle with dementia and prostate cancer
Dementia is an umbrella term used to describe a range of progressive neurological disorders, that is, conditions affecting the brain.
There are many different types of dementia, of which Alzheimer’s disease is the most common.
Some people may have a combination of types of dementia.
Regardless of which type is diagnosed, each person will experience their dementia in their own unique way.
Dementia is a global concern but it is most often seen in wealthier countries, where people are likely to live into very old age.
To study the immediate effects of heading a ball, Liverpool Hope University researchers recruited 30 recreational male football players aged between 18 and 21 years old who play once a week.
Participants headed one of two different balls – either a soft ball, around 8.8 pounds per square inch (PSI, a unit of pressure) or a 'hard' ball, at 16.2 PSI.
'10 of the participants headed balls with a PSI of around 8, while the other 10 headed balls with a PSI of around 16 – pressures at either end of FA guidelines,' said Ashton.
Researchers performed the King-Devick test, which provides an immediate indicator of head trauma or suspected concussion by measuring 'saccadic eye speed' – how quickly one can locate and identify visual targets.
King-Devick is a two-minute rapid number naming assessment in which an in individual quickly reads aloud single digit numbers.
The test revealed an overall increase in both the time and number of errors following heading.
Average saccadic eye speed decreased by around 10 per cent for both soft and hard ball groups on average, compared to the control group who didn't head a ball.
The time needed to complete the test increased by three seconds when compared to a baseline of the remaining 10 participants who didn't head a ball at all.
Usually after a knock, if the time needed for an athlete to complete the King-Devick test increases by three seconds from their normal values, it’s considered a possible concussion and they are removed from competition.
The increased times for both the soft ball group (4.32 seconds) and hard ball group (4.57 seconds) were 'so extreme that it would raise suspicion of a concussion in the case of a head injury', the research team say.
Two other tests tested the memory recall of the participants.
Spatial span – the recall of objects in space within a particular sequence – reduced by an average of 15 per cent for both ball groups compared with the control group.
Children under the age of 12 are banned from heading footballs in training in England, Scotland and Northern Ireland
And 'digit span' – the recall of certain numbers within a particular sequence – tailed-off by 20 per cent in the group heading the hard football compared to those heading the soft football.
'The group with the higher-pressure ball showed greater declines in working memory than the other group,' said Ashton.
'And overall both groups showed significant reductions in verbal and spacial working memory.'
Ashton said his study, which has been published in Science and Medicine in Football, doesn't look at the repercussions of heading a football over a number of years.
But the results showing the effects of just 20 headers suggest the cognitive damage could be even more severe over the typical timeframe of a professional