FRONTLINE's Concussion Watch has grim NFL statistics going into Sunday's games.

Even as the league is under fire for its handling of domestic abuse, one of its biggest problems remains on the field. New NFL estimates project that up to a third of all retired players could develop some form of long-term cognitive problem — such as Alzheimer’s disease or dementia — due to head injuries suffered in games.

For the third year in a row, FRONTLINE is tracking all official NFL head injuries in Concussion Watch. Our interactive database lets you search by team, player, and position to examine the game's dire toll on those who play it. 

And for an in-depth look at what the NFL knew and when they knew it, watch the Emmy-nominated League of Denial.

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