Heading a football can affect a player's brain function and memory, scientists say.

Footballers were tested before and after sessions where they were asked to head a ball 20 times by researchers at Stirling University.

They found their performance in memory tests fell by between 41% and 67%.

The results returned to normal within 24 hours but the long-term impact remains unclear, according to Stirling's University for Sporting Excellence.

Neuroscientist Dr Magdalena Ietswaart 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 football.

"Using a drill, most amateur and professional teams would be familiar with, we found there was in fact 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 football 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."

The results of the study were published in the journal EBioMedicine.

Dr Angus Hunter, of the university's 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 football.

"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 football players at all levels, as well as individuals involved in other contact sports."