Washington State quarterback Tyler Hilinski took his own life in January. He was 21. Now, six months later, his parents are sharing what they have learned about their son's death.

Speaking on NBC's "Today,", Hilinski's parents, Mark and Kym, revealed their son had chronic traumatic encephalopathy (CTE) at the time of his death. CTE has been linked to playing football and a recent study found that 99 percent of 202 deceased football players had the condition at the time of death.

Following Tyler's suicide, the Mayo Clinic in Minnesota contacted the Hilinskis, who agreed to give the hospital their son's brain for autopsy and study. The results stunned the family.

"The medical examiner said he had the brain of a 65-year-old, which is really hard to take," Mark said on the show.

Tyler's parents also participated in a lengthy feature documentary with Greg Bishop of Sports Illustrated; the story is tough emotionally but absolutely worth your time.

"Did football kill Tyler?'' Kym asked in the piece. "I don't think so. Did he get CTE from football? Probably. Was that the only thing that attributed to his death? I don't know."

Hilinski appeared in 12 games over the last two seasons for Washington State, starting the 2017 Holiday Bowl for the Cougars and playing his best game in a come-from-behind victory over Boise State. He was expected to replace Luke Falk as the team's starter in 2018. Following Hilinski's death, Washington State said it would use its spring game to promote suicide prevention and mental health awareness.