New studies will be commissioned into what causes the increased risk of dementia among professional footballers, the Football Association has said.
The increased risk was established by the 2019 FIELD study, conducted by academics at the University of Glasgow, which found footballers were three and a half times more likely to die of neurodegenerative disease than age-matched members of the general population.
The FIELD study was co-funded by the FA and the Professional Footballers' Association, and now the FA's independently chaired research task force will commission further research to work out the cause of the increased risk.
FA chief executive Mark Bullingham said: "This call for research is the next important step in our commitment to understanding more about the link between neurodegenerative disorders in former professional footballers.
"The interim findings of the FIELD study gave us some groundbreaking insight, however the parameters of the study meant that it was not able to answer exactly what causes the link, which will now be the primary focus for this research.
"Although the pandemic has impacted on our recent progress in medical research, we are now very pleased to be sending out this new call for research that's aimed at answering our question through robust and extensive analysis."
The link between football and dementia has been highlighted in recent months by confirmation of a dementia diagnosis for Sir Bobby Charlton. His England and Manchester United team-mate Nobby Stiles, who he played alongside as England won the 1966 World Cup, died with dementia last year.
So too did Sir Bobby's brother Jack, another member of the 1966 final line-up.
Two of the factors which could be behind the increased risk of disorders such as dementia among footballers are repeated heading of the ball and incidents of concussion.
PFA chief executive Gordon Taylor said: "In 2019, the initial findings from the FIELD study provided the first major insights into lifelong health outcomes in former professional footballers. It was the most extensive study of its kind, not just in professional football, but within any sport globally.
"Following the landmark findings, the PFA committed to funding further research to try and improve our understanding of what specific factors caused the link between neurodegenerative disorders in former professional footballers.
"It is hoped that new research will inform protections for current players and help make the sport as safe as possible for future generations."
A working group including representatives from the FA and the PFA is looking at the possible introduction of guidelines around heading in training at professional level. Coaches are already being advised not to practise heading in training for children of primary school age.
England manager Gareth Southgate is taking part in the HEADING study being led by the London School of Hygiene and Tropical Medicine, which is being supported by the FA.
It will invite PFA members aged 50 and over to take part in the research, which will investigate whether there is a correlation between frequency of heading and/or concussions during a career that leads to individuals being at greater risk of developing a neurodegenerative disorder.
The FA also announced on Thursday that FIFA's head of medical, Dr Andrew Massey, was also joining its research taskforce.
