The AFL is funding the first comprehensive study into the brains of retired football players who have suffered repeated knocks to the head.

It follows the early retirement of several players due to concussion and has been spearheaded by the AFL Players Association (AFLPA).

The University of Melbourne research will feature 40 young and older former players who have suffered concussions, measuring them against 20 field umpires who have not suffered concussion.

The move represents a shift in the thinking around concussion by the AFL and follows a series of concussion protocols introduced by the code.

"These sports generate a lot of money so the participants, the athletes, the stars, the people who put their bodies on the line week in week out, need to be looked after later in life," AFLPA president Ian Prendergast told 7.30.

North Melbourne forward Leigh Adams, who retired from the game in August aged just 27 after suffering three serious concussions over the past year, will be part of the study, as will 1980s star John Platten, who has recently said publicly his concussions had lasting consequences for him.

Along with Adams, Geelong's Sam Blease and Brisbane Lions defender Matt McGuire also retired on the advice of doctors because of their concussions this year.

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"It was a hugely hard decision in terms of it was my dream since I was six years old to play AFL footy," Adams said.

"To not be able to play the sport that I love any more with my mates, that I'd put 10 years of hard work in together to try and win a premiership.

"But on the other hand, I've got a wife, I've got a little baby on the way — the neurologists have said if you want to continue on, you may not remember your kid's name in 20 years' time.

"It's a very, very easy decision."

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His wife, Cassie, said the symptoms of the usually "happy-go-lucky" Adams' concussion worsened with each severe knock. He became depressed and "felt like he was losing his mind".

"He became quite fixated on things ... quite frustrated. He would lose his cool pretty quickly at things that wouldn't normally throw him," Ms Adams said.

University of Melbourne neurophysiologist Dr Alan Pearce is conducting the research. He said the first stage involved a process called transcranial magnetic stimulation.

It essentially measures the type and duration of muscle responses to the brain.

Preliminary research he conducted two years ago on retired players in their 50s showed the men had abnormal reactions to the electrical stimulus, comparable to those of stroke patients.

He said other research he conducted showed a link between these abnormalities and "loss of attention and memory span problems".

"The consistency of the brain is like custard," Dr Pearce said.

"When you get a knock to the head, the brain will move inside the head because it's in a fluid.

"I guess the analogy is being in a car accident and you keep moving forward and backwards.

"With the brain being knocked time and time again, the movement and the tearing and the shearing leads to nerve cell death and that continual process, as you start to lose more and more neurons, will start to affect mental cognitive issues."

The AFL's decision to fund the research comes in the context of litigation against the NFL in the United States by retired players who allege they have permanent brain injuries as a result of their concussions.

That litigation was inspired by research by Boston University into a controversial condition known as chronic traumatic encephalopathy (CTE).

"It's a neurodegenerative condition. It was once called punch-drunk syndrome colloquially and it was really focused on boxers, so the slurring and looking like they're really drunk," Dr Pearce said.

The Boston researchers said their work showed it was not just boxers — analysis of the brains of deceased NFL players found CTE also.

Global verification of the disease needed

But the research has been extremely controversial. The AFL and its concussion panel, made up partly of eminent neurosurgeons, have been sceptical because the research is selective and incomplete and the findings have not been reflected in research in other countries.

Mr Prendergast travelled to Boston to see the researchers at work and believes there may be something in it.

Ian Prendergast says the AFL's decision to fund the research is a welcome shift. ( 7.30 )

"I'm open-minded to all of the research and supportive of all the work that's being done," he said.

"In fact, we're of the view, based on the emerging evidence, that concussions can lead to permanent damage."

Dr Pearce's research will not measure for CTE itself, as it can only be found, if at all, in a post-mortem exam.

But he hopes it will give a much better picture of what is happening to players' brains after repeated concussions.

"One of the things about CTE is that we've got to be very careful about applying this to everyone," Dr Pearce said.

"There are only a very small number of cases of CTE in the wider picture, so we've got a lot more research to understand about it and also having verification of the disease around the world rather than in just one or two places only."

Mr Prendergast agreed the jury was "still out in terms of the impact that concussions cause", but said the AFL's decision to fund the research was a welcome shift in the code's overall approach to concussions, which was also reflected in new on-ground concussion protocols.

"There are other factors which may contribute to players suffering behavioural issues later in life," he said.

"But I think there's general acceptance that there is a very real risk that if you suffer a number of concussions, you could end up with permanent damage."

The AFL and its concussion panel declined to comment.