Former Broncos wide receiver Demaryius Thomas was suffering from CTE at the time of his death, according to his parents, who appeared on Good Morning America on Tuesday.
Thomas, 33, was found unresponsive in his shower in December. According to his parents, Thomas died after suffering a seizure which led to cardiac arrest. Dr. Anne McKee, the director of Neuropathology Core at Boston University, said Thomas' seizures were the result of off-the-field head injuries, including a car wreck and a fall down stone stairs.
"Cardiac arrest, you know, is the way that they're trying to say — what kinda happened to him," said Bobby Thomas, Demaryius' father, during the interview with GMA.
Thomas' family donated his brain to Boston University following his death. Researchers there found that Thomas had developed Stage 2 CTE.
"We found what we've seen in so many other players under the age of 34," McKee said of what they saw in Thomas' brain. "On the basis of multiple lesions in the frontal lobes and temporal lobe are beginning degeneration of deeper areas of the brain. He was diagnosed with CTE. Stage two."
MORE: Broncos, Lions pay tribute to Demaryius Thomas
Chronic traumatic encephalopathy, also known as CTE, is a degenerative brain disease that is closely linked with suffering repeated blows to the head. The disease is especially common among football players. According to a 2019 New York Times report, more than 315 former NFL players were posthumously diagnosed with the disease.
CTE cannot cause death. However, it can lead to adverse changes in personality, mood swings and memory loss, per McKee.
Thomas' parents said that his bubbly personality had given way to paranoia and isolation in the year leading up to his death.
"His mood would change and he would also isolate himself sometimes," said Katina Stuckey Smith, Demaryius' mother. "He was like 'Mom, I don't know what's going on with my body. I got to get myself together. I don't feel like myself anymore.'"
"When [the researchers] started explaining side effects, warning sides, that's when the bell started ringing," Bobby Thomas added. "When they said it, I was like 'Man, he was doing that. He did that, too.' I thought it myself because I said 'I know I could have done more.'"
CTE is untreatable and can only be diagnosed through an autopsy.
"These guys suffer in silence," McKee said. "...It's an invisible injury."
In 2013, more than 4,500 former players and their families sued the NFL for "concealing the dangers of concussions and rushing injured players back onto the field while glorifying and profiting from the kind of bone-jarring hits that make for spectacular highlight-reel footage," according to NFL.com.
"At first I didn't want to [donate Demaryius' brain]," Smith said. "And then I remembered a conversation DT and I had where he said that 'If anything ever happens to me, I want to be able to help other players.'"
