My hope is that we can develop more robust testing in his lifetime so we can prevent players from getting this bad.
I haven't seen any reports about how many concussions he might have had to indicate early onset CTE. CTE doesn't normally appear until years after the players career. At this point we aren't aware of a concussion history to try and place the blame there or if it's another psychological issue.
You do seem interested in Antonio Brown in particular.
As far as robust testing is concerned we need to develop better helmets to prevent concussions in the first place. They've been getting better but have a long way to go. And they are officiating helmet to helmet hits more closely.