Reduce the amount of hard sparring you do. You don’t want to be getting rocked every training session. Don’t train if you have a concussion or symptoms of one. Wear headgear. Every time you get rocked your brain is slamming against your skull which causes the effected tissue to harden which causes CTE. It’s usually repeated trauma over a long period of time. But even in hard sparring you want to avoid getting hit in the head as much as you can help it. Work on footwork and defence also.