Do all boxers develope dementia pugilistica?

No they don't all get Dementia,Muhammad Ali has Parkinson's syndrome,many feel brought on because of the Frazier fights (Frazier himself being slightly' punch drunk'),Wilfredo Benitez, the great Welter, is brain damaged(dementia)and to a lesser extent so is Tommy Hearns.i know two guys who were former journeymen boxers who are damaged,it's not more to do with heavyweights as some lighter weights have also tremendous punching power compared to the slight frames they are hitting.