The former Carlton star has been battling chronic traumatic encephalopathy (CTE), a condition commonly associated with athletes involved in contact sports.

His comments come as the AFL prepares to host a major conference on concussion at Etihad Stadium before round one.

Williams says he has forgotten large portions of his career, which included 250 games with Geelong, the Sydney Swans and Carlton from 1984-1997.

He was one of six former AFL players and an ex-NRL player who had been taking part in a testing program at Deakin University.

All had shown signs of brain disease.

Williams called on the AFL to do more to protect players, saying several concussions were still not being diagnosed properly and some at-risk players should not be competing every week.

"I'm not an expert but I just think players who are great players like [Geelong's Joel] Selwood and [Sydney's Kurt] Tippett and these guys are getting knocked out two or three times a year and they're nearly playing the week after," Williams said.

"There are different levels of concussion and if you're a certain level and you get knocked out there's got to be a one-month, two-month lay-off.

"They've got to get treatment and they've got to make sure that they're right before they come back."

Williams said he'd been fully concussed about four times in his career but warned that continual head knocks could lead to minor concussion.

He said the league needed to make changes to the issue of concussion across the board, including in suburban and country leagues.

"They're not getting diagnosed and they're not getting treated properly and there are going to have to be changes and I'm sure there will be in the years ahead," Williams said.

Officials from all AFL clubs will attend the March 20-21 conference which is being held to provide the league with the most up-to-date information available on head injuries, including match-day decisions.

The Concussion in Sport conference will include representatives from a range of sports and be run in conjunction with rugby league and rugby union, but will be open to any sporting group who needs to deal with concussion.

It will be held one week after the release of new guidelines on the management of concussion in sport which follow the 2012 Zurich International Consensus Conference on Concussion.

AFL Medical Officers Association Officer Dr Hugh Seward, who attended the Zurich Conference, said new initiatives relating to the match-day management of concussion would be released at the conference. AAP