So who thinks boxing causes brain problems?

So who thinks that boxing messes up the brain? Some scientists and neurologists say boxing lowers your intelligence and thinking rate, it makes you stupid and kills your braincells and makes holes in your brain. But.... some scientists and nuerologists say they've found no sings of brain damage or trauma due to boxing. They say that boxing has little to no effect on the brain whatsoever. I want to see want the fans and, I know some of us here are boxers ourselves, think about one of the most controversial theories in boxing.