Yes in about twenty years there will be all kinds of mma warriors walking around not knowing what day it is. The effects of repeated blows to the head is a slow cumulative process which you may never notice as the years go by but other people will. Take a look at old NFL players, mostly linemen who never got the glory, just had to do the dirty grunt work to win games. Most of them do not have the quality of life in their middle age. Look at Leon Spinks, the man can hardly put a sentence together, Ali is a total vegetable now. Yes brain damage can result from a good kick to the head. I've seen it myself. Years ago at the dojo I trained in a simple sparring match resulted in a knockout, ruondhouse kick caught the guy in the base of the skull, he had head gear and foot wear and still. The guy had severe headaches for months and was off work for some time, which I'm sure the wife and kids did not appreciate. He was a pretty good fighter but he never came back.