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EAST RUTHERFORD, NJ - NOVEMBER 16:   Chris Borland #50 of the San Francisco 49ers celebrates after a tackle against the New York Giants in the fourth quarter at MetLife Stadium on November 16, 2014 in East Rutherford, New Jersey.  (Photo by Al Bello/Getty Images)
EAST RUTHERFORD, NJ - NOVEMBER 16:   Chris Borland #50 of the San Francisco 49ers celebrates after a tackle against the New York Giants in the fourth quarter at MetLife Stadium on November 16, 2014 in East Rutherford, New Jersey.  (Photo by Al Bello/Getty Images)

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Gupta: 1 in 3 players will suffer cognitive problems

CNN's Anderson Cooper speaks with Dr. Sanjay Gupta about NFL linebacker Chris Borland's decision to quit football over his fear of a career of concussions.

Gupta: 1 in 3 players will suffer cognitive problems

CNN's Anderson Cooper speaks with Dr. Sanjay Gupta about NFL linebacker Chris Borland's decision to quit football over his fear of a career of concussions.