It has become a grim but familiar pattern: Soon after an N.F.L. player dies, his surviving family faces the decision about whether his brain will be donated to scientists who test for signs of chronic traumatic encephalopathy, the degenerative brain disease associated with repeated hits to the head.
Relatives of Phillip Adams faced that choice last week after Adams, whose six-year N.F.L. career ended after the 2015 season, fatally shot six people and then himself in his hometown, Rock Hill, S.C. The family asked that his brain be sent to the C.T.E. Center at Boston University, the leading site for research on the disease, which has been found in hundreds of football players and other athletes but can be diagnosed only after death.