Former Nashville Predators captain Greg Johnson had chronic traumatic encephalopathy (CTE) when he died at age 48, according to family members and the Concussion Legacy Foundation.

Johnson died by suicide at his home in Detroit on July 7, 2019. His brain was analyzed by Dr. Ann McKee of the Boston University CTE Center, who diagnosed Johnson with CTE.

CTE is a progressive brain disease that primarily affects people who have suffered concussions or repeated head injuries. Diagnosis can only be determined after death.

"We never once thought this disease was something he struggled with," Johnson's widow, Kristin Johnson, said in a news release Tuesday. "He experienced very few symptoms that we knew of, but he spoke of his concussions often."

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Johnson played 12 seasons in the NHL, including seven with the Predators (1998-2006). He scored 93 goals and had 145 assists in 502 games in Nashville, and was the franchise's second captain, serving from 2002-06.

The native of Thunder Bay, Ontario, was a second-round pick by the Philadelphia Flyers in 1989. He retired from hockey in 2006 after playing 785 NHL games.

Johnson's family said concussions suffered during his playing years were a factor in his decision to retire.

"He knew his hockey career had a profound impact on his brain," Kristin Johnson said.

According to the Concussion Legacy Foundation, a study in 2019 found that a diagnosed concussion doubles the risk of suicide. To date, there has been no formal study linking CTE or traumatic brain injuries with suicide.

Johnson is the second known Predators forward to be diagnosed with CTE. Forward Wade Belak, who played three seasons in Nashville (2008-11), was found dead on Aug. 31, 2011 and later diagnosed with CTE.

According to the foundation, 17 of 18 NHL players studied in the U.S. and Canada have been diagnosed with CTE. The list includes Derek Boogaard, Henri Richard, Stan Mikita and Bob Probert.