The 24-year-old addressed the issue during an appearance on Channel 9's Footy Classified on Thursday night.
Asked by panellist Matthew Lloyd if he fears for his life after football, Selwood replied: "Yeah, you do. It's scary what's happened to some people.
Diesel can't recall chunks of career
"We wouldn't send the general manager of the players' association over to America if we weren't worried about it."
Selwood has copped numerous bumps to the head during his career and has been knocked out twice.
The first time was during Geelong's narrow win over St Kilda at the MCG in round one of the 2011 season; the second was during a match against the Brisbane Lions at the Gabba last year.
Players should have enforced layoff: Williams
With this in mind, two-time Brownlow medallist Greg Williams, who has been diagnosed with a degenerative brain condition that he links to repeated head-knocks, recently said that Selwood was "too courageous for his own good".
Williams added that that Geelong "has to protect him because he can't protect himself".
But Selwood is adamant that both he and the Cats are doing everything they can to protect his long-term welfare.
"I've been and had a brain scan … and we'll just keep revisiting those," he said.
"At the moment it's really hard to know (the long-term effects of concussion) because we haven't got a baseline on what actually happens.
"Concussions are so different. Every case is so different.
"In my case, I've had the week off both times after I've been concussed. Some blokes don't need that."
In contrast to Williams' view, Selwood is adamant that he understands the need to take himself out of games if he cops a serious head-knock.
Recalling the incident at the Gabba last year, he said: "When I got knocked out, I got asked a couple of simple questions on the bench and I looked at the doctor and said, 'I can't go back on, I'm not right here.'
"It's a little bit different to what happened back in the day, I guess."
Selwood also insists that no one has yet told him to change the way he plays.
Yet the three-time premiership player says he is prepared to alter the way he goes about his business on the field if he becomes convinced that he should.
"I will change, if it's going to protect me more," Selwood said.
"If the doctors say 'wear a helmet' or something like that, then you would do it.
"I would wear a helmet this season if it comes out that it is going to help you.
"I see why (some people say I should change), because I do draw a lot of free kicks that are above the shoulders and are above the head … but it's just the way I've learned to play.
"And if I can see myself changing and protecting myself better, I'll do it.
"But there's so many things that you learn as a kid that you just can't take out of your game. It's just so hard to change.
"There are times in games when you have to go for the footy, and that's one thing that I've never had a problem with."
The comments made by Williams have caused some angst in Selwood's family.
"Especially when you mother messages you and says, 'Are you okay?', as if something's gone wrong," he sai
"And nothing's gone wrong in this case."
Joel Selwood is a midfielder in AFL Fantasy. He averaged 103 points in 2012. Register your team at our AFL Fantasy hub.
Adam McNicol covers Geelong news for AFL.com.au. Follow him on Twitter at @AFL_AdamMcNicol