NFL is much more conducive to repeat head knocks than the AFL though. I think the worry in the AFL is for your in an under inside mids who are crashing in repeatedly all game.30 years might not be long enough. Sporting codes across the globe have spent decades burying their knowledge of brain injuries - one of the many lawsuits against the NFL related to their knowledge of a link between football and brain injuries as far back as 1998. It's taken them til the last 7-8 years to start taking action, and it's still not action that will prevent CTE. Some of the research is really terrifying - there was a case in the US where a guy who only played a couple of years of college football developed CTE and took his own life; there have been symptoms of CTE discovered in soccer players just from heading a ball. There's a theory that you don't even need a direct blow to the head to contribute to brain injuries, just the whiplash effect can do it.
If sport ever truly took this seriously it would be non-contact, because the research from the US suggests this is epidemic - it's just been covered up. Think I'm being dramatic? Google Jovan Belcher; Aaron Hernandez, at just 27, was found to have the most advanced case seen in someone that age when he murdered one, and probably three people. Google wrestler Chris Benoit.
Boston University said in 2017 that, of 111 brains belonging to former NFL players that they'd examined, 110 had signs of CTE.
The only surprise here is that we haven't heard more about CTE in Australia.