It's a good question.  In terms of diagnosed, acknowledged concussions probably not many   But there's this: https://www.washingtonpost.com/news/early-lead/wp/2014/10/17/offensive-linemen-are-the-football-players-most-likely-to-play-while-concussed-new-studies-show/?noredirect=on&utm_term=.e9e2c59bb825   Whether it's primary, or subsequent to traumatic brain injury,  Incognito has openly acknowledged being treated for depression and being involuntarily committed