The last NFL season was dominated by worries about concussions and other head injuries more than any before, but it ended on an upbeat note when Green Bay Packers quarterback Aaron Rodgers shook off two regular season concussions to win Super Bowl MVP honors. But after the bright lights go down, the long-term effects of brain injuries linger in the dark. And no one, it seems, knew that better than Dave Duerson. Duerson played 11 seasons as a battering ram, a safety for the Chicago Bears and New York Giants. Last week he committed suicide, thrusting the worries about the long-term consequences of repeated blows to the head back into the spotlight.