Heading a soccer ball causes instant changes to the brain

The study from Scotland's University for Sporting Excellence published in EBioMedicine is the first to detect direct changes in the brain after players are exposed to everyday head impacts, as opposed to clinical brain injuries like concussion.

A group of soccer ball players headed a ball 20 times, fired from a machine designed to simulate the pace and power of a corner kick. Before and after the heading sessions, scientists tested players' brain function and memory.

Increased inhibition in the brain was detected after just a single session of heading. Memory test performance was also reduced by between 41 and 67 per cent, with effects normalising within 24 hours.

Whether the changes to the brain remain temporary after repeated exposure to a soccer ball and the long-term consequences of heading on brain health, are yet to be investigated.

Played by more than 250 million people worldwide, the 'beautiful game' often involves intentional and repeated bursts of heading a ball. In recent years the possible link between brain injury in sport and increased risk of dementia has focussed attention on whether soccer ball heading might lead to long term consequences for brain health.

Cognitive neuroscientist Dr Magdalena Ietswaart from Psychology at the University of Stirling, said: "In light of growing concern about the effects of contact sport on brain health, we wanted to see if our brain reacts instantly to heading a soccer ball. Using a drill most amateur and professional teams would be familiar with, we found there was infact increased inhibition in the brain immediately after heading and that performance on memory tests was reduced significantly.

"Although the changes were temporary, we believe they are significant to brain health, particularly if they happen over and over again as they do in soccer ball heading. With large numbers of people around the world participating in this sport, it is important that they are aware of what is happening inside the brain and the lasting effect this may have."

Dr Angus Hunter, Reader in Exercise Physiology in the Faculty of Health Sciences and Sport, added: "For the first time, sporting bodies and members of the public can see clear evidence of the risks associated with repetitive impact caused by heading a soccer ball.

"We hope these findings will open up new approaches for detecting, monitoring and preventing cumulative brain injuries in sport. We need to safeguard the long term health of soccer ball players at all levels, as well as individuals involved in other contact sports."

Dr Ietswaart and Dr Hunter were supported in the research by Stirling neuropsychologist Professor Lindsay Wilson and PhD student Tom Di Virgilio, consulting with leading Glasgow University Medical School Neuropathologist Dr Willie Stewart and a wider multi-disciplinary team.

In the study, scientists measured levels of brain function using a basic neuroscience technique called Transcranial Magnetic Stimulation (TMS). The findings from this study, funded by the NIHR Brain Injury Healthcare Technology Cooperative (HTC) are the first to show the TMS technique can be used to detect changes to brain function after small, routine impacts.