Brent Boyd

When Brent Boyd was playing the 1980's as an offensive guard for the Vikings, brain injury awareness was an afterthought. "We didn't even know what a concussion was...you got your bell rung, you got dinged," Boyd told CBS News. After hearing of other players' deaths following apparent neurological problems, Boyd, 53, realized where his depression, dizziness, and headaches might be coming from. His struggle led him to find a retired player's advocacy group called Dignity After Football. He also agreed to donate his brain to the CSTE.

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