The CTE Center at Boston University announced Tuesday that an examination of former Broncos receiver Demaryius Thomas’ brain revealed he had Stage 2 CTE at the time of his death last December at age 33.
CTE — chronic traumatic encephalopathy — is a progressive degenerative brain disease caused by repetitive head trauma.
The Concussion Legacy Foundation announced Thomas’ diagnosis in conjunction with his family.
“Once I became aware of CTE and began to familiarize myself with the symptoms, I noticed that Demaryius was isolating himself and I saw other changes in him,” said Thomas’ mother, Katina Smith, in a statement. “He was just so young and it was horrible to see him struggle.”
In a press release, the BU CTE Center acknowledged the speculation Thomas’ death may have been related to an epileptic seizure, but said it is “far more likely” he developed epilepsy after his 2019 car accident in Denver.
Thomas died on Dec. 9, 2021, when he was found unresponsive in a shower of his Georgia home. The Fulton Co., medical examiner has not revealed a cause of death, but Thomas’ parents donated his brain to research at Boston University.
According to the Concussion Legacy Foundation, Stage 2 symptoms include “aggression, depression, anxiety, paranoia and suicidal ideation.”
The repeated hits to the head triggers progressive degeneration of the brain tissue. CTE can only be diagnosed posthumously and BU conducts its research once the family of the deceased person donates the brain.
Last week, the family of former MLS player Scott Vermillion announced he had Stage 2 CTE. He died from an accidental overdose in December 2020 and was the first former MLS player diagnosed with CTE.
Last year, the family of former NFL receiver Vincent Jackson, who played college football at Northern Colorado, announced he suffered from Stage 2 CTE at the time of his February 2021 death at age 38.
In 2019, BU’s CTE Center analyzed the brains of 266 deceased former amateur and professional football players and estimated a person’s risk of developing CTE doubles for every 2.6 years of playing the sport. At the time, BU said the average playing career in the NFL was 3.3 years.
Thomas was a first-round pick by the Broncos in 2020 and caught 665 passes for 9,055 yards and 60 touchdowns in nine years for the club, winning the Super Bowl in 2015.
Thomas was traded to Houston during the 2018 season and played seven games for the Texans and 11 games for the New York Jets in ’19. He announced his retirement last summer.
“(Thomas’) father and I hope all families learn the risks of playing football,” Smith said. “We don’t want other parents to have to lose their children like we did.”
This story will be updated.