Professor Willie Stewart also suggested that the sport's authorities should consider banning heading altogether at all levels.

The world-leading expert on dementia in football has called on the authorities to explore removing heading completely from the game and suggested that footballs should be sold with a health warning after major new research into the national game's risks.

Professor Willie Stewart, whose landmark research previously proved football's dementia link, has delivered a series of hugely significant new findings, which include no reduction in the risk of brain disease among former professionals who played with new synthetic balls in the 1990s but dramatically increased dangers for outfield players compared to goalkeepers.

The research, which studied the health records of around 8,000 former players and directly followed The Telegraph's campaign for answers, found that outfield players were almost four times more likely to be diagnosed with neurodegenerative disease.

There was virtually no added risk for goalkeepers but defenders were specifically at a five-fold greater risk, again suggesting that repeated heading and head impacts is the cause of the dementia risk. The studied players were all born between 1910 and 1969 - and played in the period between 1930 and the 1990s - but there were no significant changes in dementia risk according to the era. The leather and synthetic balls are an almost identical weight and, while the old balls did absorb water and then become heavier, this also meant that they were slower through the air.

"We are at a point in this current data to suggest that footballs should be sold with a health warning saying, 'Repeated heading of a football may lead to an increased risk of dementia'," said Prof Stewart.

"I would not fall into the comfort zone of thinking modern balls are somehow changing the risks - the risks could actually be higher. Unlike other dementia and other degenerative diseases, we know what the risk factor is here. It is entirely preventable."...

From The Telegraph.