The original story the movie is based on is very good too. I think this is it:

http://www.gq.com/story/nfl-players-brain-dementia-study-memory-concussions

They don't just happen in football (though they do happen a lot in football). Cheerleading, soccer, synchronized swimming, cycling and other sports all have their share.

Dr. Omalu also seems to have lived Schopenhauer's famous quote:

"All truth passes through three stages. First, it is ridiculed. Second, it is violently opposed. Third, it is accepted as being self-evident."