Had this world champion kickboxer on my FB feed who had become a crusader against any minor doing any sparring in the gym, only adults who had signed a waiver could do it but he adviced against it, said the brain damage occurs much earlier than people assume, any hit causes damage and in competition he said an expert could often see after the first exchange signs of brain damage, before the fighters looked even affected to the average viewer. Of course he had a lot of opposition from fight fans saying he should butt out, we're not going to do away with fighting. Since I'm not an expert I can't have a really informed opinion myself.
