Here's the #1 fact, if we all lived loing enough we would all get Parkinson's, it's the natural breakdown of the brain. Now the disease that people like Ali, Freddy Roach, and Michael J. Fox have are just advanced cases of Parkinson's and in those cases it is my belief that Ali and Roach had their situations moved along by boxing and Fox just got the shit end of the stick genetically.

It's pretty much common sense getting punched in the head repeatedly isn't going to do you any favors with your brain.