A leading brain disease researcher says his landmark taxpayer-funded study into the brains of footballers is likely to be wound up due to the AFL withdrawing its support.

The million-dollar study, which hopes to lead to a diagnostic for brain diseases including Alzheimer's and CTE (chronic traumatic encephalopathy), is at an impasse with researchers now saying they're unable to access retired AFL footballers despite league representatives giving assurances they would help.

Christopher Rowe, an Austin Health medical specialist and the director of the Australian Dementia Network, said the AFL had indicated his study would have access to players who had taken part in a 2014 medical survey. 

The results of the survey, which involved 500 retired AFL players, have never been released publicly.

"It was part of the grant application that we said we'd be able to access players through that [past players] register, but that turned out not to be," Professor Rowe said.

He added the AFL initially seemed supportive of the study, but gradually became less enthusiastic.

"I discussed [the study] with the AFL and there were expressions of support, this was deemed to be a worthwhile project," he said. 

"Unfortunately, it's been very frustrating trying to recruit players through the AFL."

Professor Rowe said it seemed the AFL was "hesitant" to support research relating to brain disease caused by concussions.

"I think both sides of this argument have concerns about the findings of a possible diagnostic test," he said. 

The study was only able to gain access to six players through the AFL, well short of the 80 needed to complete the study.

Dr Rowe said the research would have to be wound up unless he could access more players.

"We're going to pull the plug," he said.

The study was successfully able to complete the other aspect of the research which involved Vietnam veterans and motor vehicle accident victims.

'I'm not shocked at all'

Neurologist Alan Pearce said it was not surprising the AFL had not been cooperative with information and access.

"I'm not shocked at all," he said.

Dr Pearce began research for the AFL in 2015 but blew the whistle on the league three years later, claiming it didn't provide him with any retired footballers in the retired players register after 18 months.

"They were adamant they would send me the players and that didn't happen for about 18 months," he told 7.30.

Dr Pearce is also concerned about the effectiveness of the past players survey, saying players may have fallen through the cracks.

7.30 has seen a document addressed from the AFL to a survey participant, which told the player he did not require "immediate follow-up".

Dr Pearce alleges the player had severe symptoms of a brain disease before the survey and they had worsened since.

In a statement, an AFL spokesperson said the league was investigating its concussion management.

"The AFL's independent of the work, research and advice it has been provided will be finalised in due course," the spokesperson told 7.30. 

Watch this story on 7.30 tonight on ABC TV and ABC iview.