The parents of Washington State quarterback Tyler Hilinski say an autopsy performed after his January suicide showed evidence of chronic traumatic encephalopathy in his brain.

Speaking Tuesday to NBC's "Today," Mark and Kym Hilinski said the Mayo Clinic conducted the autopsy on Tyler, who died at 21 on Jan. 16 in Pullman, Washington. Police say Hilinski shot himself in the head with a rifle that belonged to a former teammate. The autopsy findings showed Stage 1 CTE.

"Did football kill Tyler? I don't think so," Kym Hilinski said in a Sports Illustrated documentary about Tyler's life. "Did he get CTE from [playing] football? Probably. Was that the only thing that contributed to his death? I don't know."

Mark Hilinski told "Today" that the medical examiner determined Tyler "had the brain of a 65-year-old, which is really hard to take." Tyler Hilinski's parents said their son exhibited no obvious signs leading up to his suicide, and Tyler had never fired a gun until the day before his death. But they told Sports Illustrated that Tyler had become less responsive to calls and text messages late last season and after a family vacation to Mexico in January.

Washington State said in a statement to "Today" that it has enhanced its protocols for football players, including a second formal mental health screening and meetings with players "who might be at risk for mental health issues." Tyler Hilinski's family has started Hilinski's Hope, a foundation to help schools better support athletes dealing with mental illness.

"People need to keep talking about suicide and mental illness and mental health," Kym Hilinski said. "We need to erase the stigma. ... There's not enough out there for these beautiful athletes that give of themselves to their colleges, but their minds aren't taken care of."

Mark and Kym Hilinski have spoken to their younger son, Ryan, a high school quarterback committed to play at South Carolina in 2019, about the results of Tyler's autopsy. Ryan Hilinski told Sports Illustrated that while the information "scared me a little bit," he intends to continue playing.

"I'm all bought into football, of course," he said, "and I think Tyler would want me to do the same thing. I don't think he'd want me to stop."