Repeated heading of a football leads to an increased risk of brain injury, doctors have warned.
Researchers in the US studied MRI scans of 38 amateur football players and found that those who headed the ball over 1,000 to 1,500 times a year showed significant signs of changes to the brain.
Dr Michael Lipton, who led the study, said the people who headed the ball most were "much more likely to find changes in the brain that were extremely similar to what we see in people with concussion or mild traumatic brain injury."
Dr Lipton's team found a heading "threshold" of approximately 1,000 times a year, below which no damage appears to be done, although further studies are required.
"1,000 times may seem like a lot but we had players who were heading the ball more than 6,000 times a year," said Dr Lipton, of the Albert Einstein College of Medicine in New York.
The results, presented yesterday at the annual meeting of the Radiological Society of North America, showed that brain regions responsible for attention, memory and visual functions were affected.
Alongside the imaging study, the researchers also found that the more heading people had done in the last year, the more likely they were to perform poorly on cognitive tasks, especially on tests of attention.
"Putting together the imaging findings and the cognitive findings, not only can we see something in the brain that looks like it might be a traumatic consequence of heading the soccer ball a lot, or perhaps too much, but that there might be real life consequences to that exposure as well," Dr Lipton added.
But Dr Andrew Rutherford of Keele University, who studies the neuropsychological consequences of heading a football, was unconvinced by the results.
"I would be fairly sceptical," he told Sky News. "People who head a football are competing. They clash heads and get hit by the elbows of other players. Unless that is controlled you do not know whether you are looking at the consequences of concussion."
Dr Lipton conceded more research was required, while calling on football authorities to take the lead.
"This is preliminary information that is very compelling and I think pushes us to do further research to understand what the problem is and how we can deal with it.
"I really believe that it is incumbent on the people who are in control of soccer, such as youth soccer organistations, to get involved and be at the forefront of doing the research that will define the safe parameters and determine if, what and how its safe for this type of play to continue.
"The hopeful message of the study is that there seem to be a safe range of parameters in which you can play the game and even head the ball."
Dan Pope, Club Website editor
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