Ex-football players are three-and-a-half times more likely to die from dementia than non-players in the same age range, a landmark study of more than 7,500 former professionals has found.
The research confirms the fears of campaigners who have long suspected a link between devastating brain injury and football, whether through repetitive heading or collisions.
As many as 11% of the ex-pros were found to have the disease against a 3% incidence among non-players, seemingly supporting those demanding greater awareness and care over concussion in the sport.
Experts led by a team from the University of Glasgow compared the deaths of 7,676 ex-players born between 1900 and 1976 who played professional football in Scotland to 23,000 non-players.
The health records of 11% of the ex-players who had passed away stated they had died from dementia, compared to around 3% for the socio-demographically matched sample.
The study - titled 'Football's Influence on Lifelong Health and Dementia Risk' or FIELD for short - found that deaths in ex-footballers were lower than expected up to age 70, and higher than expected over that age.
Perhaps unsurprisingly given their fitness levels, the former players lived three and a quarter years longer and were less likely to die of many diseases such as heart disease or lung cancer.
The 22-month study was funded by the Football Association and the Professional Footballers' Association, bodies which have both been criticised for a lax response to the dangers posed by heading the ball.
Consultant neuropathologist Dr Willie Stewart, who led the study, called it the largest ever to look at the incidence of neurodegenerative disease in any sport.
While it does not say why the players have a higher rate of dementia, campaigners will immediately point to the heading of the football or the heavier balls used for much of the last century.
The report said the "risk ranged from a five-fold increase in Alzheimer's disease, through an approximately four-fold increase in motor neurone disease, to a two-fold Parkinson's disease in former professional footballers compared to population controls".
The family of former England striker Jeff Astle, who developed dementia and died in 2002 aged 59, have long urged football authorities to launch a comprehensive investigation.
The inquest into his death found heading heavy leather footballs repeatedly had contributed to trauma to his brain, with the pathologist saying it looked "the brain of a boxer".
His daughter, Dawn Astle, and wife, Laraine Astle, told Sky News they always believed there was a link between football and dementia, but were "shocked" at the "staggering numbers".
Dawn said: "The deaths of all these players must remain on the conscience of the game forever.
"Whatever the FA does, it should be across the whole game. I know this was a study looking at the deaths of professional footballers but they shouldn't assume this is just a professional footballer's problem.
"It could be just a big a problem in the amateur or grassroots game.
"There's no evidence that it's a generation thing or to do with a leather football. You cannot assume that just because footballs are lighter and all these concussion procedures are in place players are safer, they're on dangerous ground.
"I don't think dad would want heading banned but it's about having choice.
"Life is about risk and you can't live in a bubble but the important thing is knowing what the risks are. You can't make an informed decision if you don't know the risks."
FA chairman Greg Clarke said the whole game "must recognise that this is only the start of our understanding and there are many questions that still need to be answered".
"It is important that the global football family now unites to find the answers and provide a greater understanding of this complex issue. The FA is committed to doing all it can to make that happen."
Currently, there are more than 850,000 people in the UK living with dementia and the number is expected to rise to more than a million by 2025.