Williams has taken part in recent brain testing at Deakin University, where he has been diagnosed with symptoms of chronic traumatic encephalopathy (CTE), a condition commonly found in athletes from contact sports who have experienced head knocks.
Williams, who played 250 games with Geelong, the Sydney Swans and Carlton between 1984 and 1997, told Channel Seven's Sunday Night program he couldn't remember large chunks of his career.
Five other former AFL players and one former NRL player also took part in the Deakin University testing, with all showing symptoms of brain disease.
Williams told SEN radio on Monday he would still have played football even if he'd known about the risks of concussion, but said a lot of concussions still weren't being diagnosed and treated properly.
"I'm not an expert but I just think players who are great players like [Joel] Selwood and [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. And they've got to do something about it and they've got to make sure that it's not affecting the player."
Williams said he had been knocked-out about three or four times in his career, but said the continual head knocks footballers took could also cause minor concussion.
Williams said concussion was not unique to AFL players, with suburban and country players and particularly sportswomen at risk.
"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.
Hawthorn football manager Mark Evans told SEN on Monday concussion was "taken far more seriously" in the AFL than it was 15-20 years ago.
"The procedures for a player returning to play the following week are pretty strong and they do this concussion baseline test early in the year and they must get back to that if they're to be selected the following week," Evans said.
"And the protocols this year have been tightened right up. Now you'll see that anyone with any visible [signs of concussion] if they've got a little bit groggy for a little while they don't return to the game."
Evans suggested the concussion rules could still be tightened to safeguard against situations where coaches might be tempted to second-guess the club doctor.
"What we are going to need over time is that the rules reflect that [the wellbeing of the player is paramount] so coaches can accept that call rather than feel like they need to question [it] when the game's in the balance," Evans said.
"Like if there is the potential for a concussion the doctor may need 10 or 15 minutes to make that assessment, so coaches and everyone else on the bench just has to accept that at the moment.
"But maybe somewhere in the future there needs to be some ability to use your sub in that assessment."
Nick Bowen is a reporter with AFL.com.au. Follow him on Twitter: @AFL_Nick
