Former Celtic captain and manager Billy McNeill has dementia

A central defender, the 76-year-old Celtic great's glittering career saw him become the first British player to lift the European Cup when the Hoops won the trophy in 1967 and he also had two spells as the Glasgow club's manager.

His family told Scottish newspapers that McNeill had been diagnosed with the illness seven years ago and was now unable to speak more than a few words at a time.

They added they had deliberately decided to make his condition public ahead of the 50th anniversary of Celtic's 2-1 win over Inter Milan in the 1967 European Cup final in Lisbon.

McNeill is being cared for at his home in Glasgow by his wife Liz, 73.

"His concentration is not as good as it was and he now can't communicate very well," she told the Sunday Mail.

"I think it's the right time for us to talk about this now. Heading the ball and the possibilities of concussive effects on the brain needs more discussion. 

"We don't know if Billy's dementia is linked to his football. More research needs to be done." 

Earlier this month FIFA, football's global governing body, said there was no conclusive proof that heading a ball causes an increased risk of brain disease, after the release of a study on footballers who died from dementia.

"To our very best knowledge, there is currently no true evidence of the negative effect of heading or other sub-concussive blows," FIFA said.

"Results from studies on active and former professional football players in relation to brain function are inconclusive."

A British study said professional footballers are at heightened risk of developing a brain disease that can cause dementia and is usually found in boxers and American football players.

But the study examined just 14 retired footballers with dementia and did not show whether the damage inflicted on their brains had been caused by heading the ball, aerial collisions with other players or something else.

CTE can only be diagnosed posthumously and a very small number of former footballers are known to have had the disease.

They include former West Bromwich Albion and England striker Jeff Astle, who died in 2002 aged 59.

Astle was originally diagnosed with early-onset Alzheimer's, but a re-examination of his brain revealed he had died from CTE that a coroner said was brought on by the "industrial disease" of heading the ball.