Dr Willie Stewart of the University of Glasgow has said the sport should now come with a warning regarding the dangers of heading in the sport over the course of a player’s career.

Previous studies had shown that footballers are more at risk of dying with dementia or other neurodegenerative diseases than the general population and Stewart says a new study published in the journal JAMA Neurology provides the “missing link”.

“With the current data we’re now at the point to suggest that football should be sold with a health warning saying repeated heading in football may lead to an increased risk of dementia. That’s where we are now, that cannot be ignored,” Stewart is quoted as saying by The Guardian.

“In the previous study we didn’t have sufficient data to be able to look at the important factor: exposure to football. What we could say last time was that being a footballer meant your risk of dying with a degenerative brain disease was higher, but we couldn’t say what in football was doing it.

“Now, through using our surrogates for exposure to heading and brain injury, which are field position and length of playing the game, we can see that if you’re in a position where you’re exposed to a high level of head impacts or you play the game longer, your risk is higher.”

He added: “The data from this paper is the missing link in trying to understand this connection between sport and dementia. We put that together with what we know about the mortality risk… and there really isn’t anything else. There is no other proposed risk factor and this is one we could really address and eliminate this disease.

“I think football has to ask the difficult questions: is heading absolutely necessary to the game of football? Is potential exposure to degenerative brain disease absolutely necessary? Or can some other form of the game be considered?”

Of the 7676 former football players in the study, five per cent (386) were diagnosed with a neurodegenerative disease, compared to just 1.6% (366) of the 23,028 in the control group.

The study concluded that the danger varies between positions and length of career.

Defenders are five times more at risk of catching neurodegenerative diseases than the general population, while goalkeepers are the least susceptible.

The Football Association (FA) and Premier League recently issued new guidance to clubs regarding headers in training.

The new policy recommends teams limit the number of “higher-force” headers to 10 per week.

The guidance applies to teams at all level of the game.

“It will be recommended that a maximum of 10 higher-force headers are carried out in any training week,” a statement read.

“This recommendation is provided to protect player welfare and will be reviewed regularly as further research is undertaken to understand more regarding the impact of heading in football.”

Originally published by Goal.