Former Newcastle United and England captain Alan Shearer fears he may be at risk of suffering from dementia due to heading footballs.
The 47-year-old is the Premier League's record scorer with 260 goals and enjoyed an 18-year career with Southampton and Blackburn as well as his hometown club.
Shearer also netted 30 goals in 63 appearances for England but has revealed that he has concerns about his long-term health.
Speaking to the Daily Mirror, he said: "For every goal I scored with a header during a game, I must have practised it 1,000 times in training. That must put me at risk if there is a link."
He has had tests to examine how heading the ball has affected his brain.
"The tests were pretty nerve-wracking," he said.
"I have got a terrible memory.
"I don't know if that is because I don't listen, but I have got a poor memory.
"When you play football as a professional you expect in later life you are going to have problems with your knees, your ankles, or you back, like I have.
"But never did I think playing football could be linked to having a brain disease. That is why the research has to be done."
Shearer believes more research needs to be carried out and greater support for ex-players with dementia should be on offer.
"It's a tough game, it's a brilliant game, but we have to make sure it's not a killer game," he said