Boston University doctors posthumously diagnosed former Broncos great receiver, Demaryius Thomas, on Tuesday with stage 2 CTE, shedding light on his final days before his passing at age 33 in December.
However, the exact role football and CTE played in his death is complicated by a car wreck Thomas suffered in 2019 in Denver, leading to seizures.
A cause of death has not yet been determined by the coroner's office in Fulton County, Ga., however, Boston university doctors believe Thomas died from a seizure at his home, according to a New York Times article published Tuesday. '''
“He had two different conditions in parallel,” said Dr. Ann McKee, the neuropathologist who studied Thomas’s brain.
McKee added in an interview with ABC News, "CTE itself does not cause death. You don't die from CTE. What CTE does is it changes your behavior and your personality."
McKee added that seizures are not typically connected to CTE. Teammates were worried about Thomas in the days leading up to his death because of his seizures. He was scheduled to travel to Denver to be honored for a game in the fall, but that was postponed.
Though traded to Houston midseason in 2018, Thomas eventually retired as a Bronco, paving his way back to his eventual induction into the team's Ring of Fame. Thomas arrived in Denver in 2010 as a first-round draft choice, known for his blocking and athleticism at Georgia Tech.
He evolved into the franchise's second-most accomplished receiver, behind only Rod Smith. Thomas, who would have turned 34 last Christmas Day, earned five Pro Bowl berths and two All-Pro selections.
Thomas caught 724 passes for 9,763 passes for 63 touchdowns. He will forever be known for his walk-off score against the Pittsburgh Steelers in the playoffs, catching a slant pass from Tim Tebow.
Thomas announced his retirement in June. Talking with the Broncos website, Thomas admitted he was still trying to find his way post-football, having been motivated to play another season to amass 237 receiving yards to reach 10,000 for his career.
He was struggling to find the balance with his seizure medication, but was also showing signs of CTE — which include memory loss and paranoia — his mother told ABC News.
"His mood would change, and he would also isolate himself sometimes. He was, like, 'Mom, I don't know what's going on with my body. You know, I gotta get myself together,' and he said, 'I don't feel like myself anymore,'^" Katina Stuckey Smith said.
It was a feeling Thomas echoed, if only slightly when he announced his retirement.
"It ain’t easy leaving football,” Thomas said in the video filmed from his home. “Because that’s my main thing, I am just trying to find self and put out love.”
Troy Renck at KMGH first reported this story.