Professional footballers are more than three times likely to die of dementia than those of the general public, new research commissioned by the Football Association (FA) and Professional Footballers' Association (PFA) has showed.
Health records of more than 7,000 footballers in Scotland were compared to those of over 23,000 men who did not play professional football.
Experts from Glasgow University led the study, which the FA said was "one of the most comprehensive studies ever commissioned globally into the long-term health of former professional footballers".
The issue of dementia in football gained prominence after it was claimed in 2014 that former England striker Jeff Astle died due to a brain condition caused by heading footballs. Astle died at the age of 59 in 2002.
In the lengthy findings, an FA statement on the FIELD study revealed that "former professional footballers in this study lived three-and-a-quarter-years longer [than those of the general public] and were less likely to die of many diseases such as heart disease or lung cancer".
"However, they were more likely to die of dementia," the statement continued.
"The research found that the health records of 11 per cent of the former footballers who had passed away stated that they had died from dementia, compared to around three per cent for the socio-demographically matched sample.
"The study showed through statistical analysis on the full data set that the professional footballers in this research were around 3.5 times more likely to die of dementia than the matched population.
"However, overall, this group of former professional footballers did not on average die earlier of dementia than dementia sufferers in the general population.
"As you would expect, there are many questions relating to this data that do not, at present, have answers.
"For example, The FIELD study was not able to determine what exactly causes the increased rates of dementia.
"The study does not determine whether the cause is due to concussions suffered by the group of professional footballers, or concussion management, or heading of the football, or style of play, or the design and composition of footballs over the years, or personal lifestyle, or some other factor."
The FA added that the findings had already been reviewed, with a host of recommendations offered.
"In order to consider next steps, we constituted an independently chaired Medical & Football Advisory Group which has reviewed the findings," the statement added.
"It recommended that we re-issue both the current FA Concussion Guidelines and best-practice advice for coaching heading, while also asking football to consider further steps to improve head injury management, for example by supporting UEFA’s proposals to introduce concussion substitutes.
"The Medical & Football Advisory Group also concluded that more research is needed into why players had been affected, but that there is not enough evidence at this stage to make other changes to the way the modern-day game is played.
"In addition, the Medical & Football Advisory Group has recommended that the best way we can support the next phase is by convening a specialist Research Taskforce to assimilate the research currently available and set the direction for new research to be commissioned both domestically and globally."
The FA also said they have "written to both FIFA and UEFA to offer our full support on future research in this area" in the bid for answers.
Commenting on the findings, FA chairman Greg Clarke said the study was just the start of the process.
"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," Clarke said.
"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."
PFA chief executive Gordon Taylor added: "These findings are a matter of considerable importance to our members … it is now incumbent on football globally to come together to address this issue in a comprehensive and united manner."