ST. PAUL, Minn. (AP) NHL Commissioner Gary Bettman's reluctance to link hits to the head in hockey with a degenerative brain disease found in several deceased former players has reached Congress.

League attorneys filed Bettman's letter to Connecticut Sen. Richard Blumenthal with U.S. District Judge Susan Richard Nelson, who's presiding over the concussion lawsuit against the NHL. Bettman's 24-page response to Blumenthal was dated Friday. He said research on the link between concussions and chronic traumatic encephalopathy ''remains nascent.''

The Connecticut Democrat wrote June 23 to Bettman about the league's stance on CTE.

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He cited in his letter the discovery of CTE in the brains of six former players after their deaths in recent years. Blumenthal is the ranking member of the Senate subcommittee on consumer protection, product safety, insurance and data security.