Read the article on the study references below. It was 99 percent. Doesn't mean they are all totally dysfunctional but they are all
Impacted. It's probably true for hockey also.
I did read it. The study acknowledges that there may be bias since the only relatives donating brains are those who feel their loved one showed signs on brain damage, without a bunch of brains of players who'd never exhibited any signs the study is flawed.
