Explainer-What is CTE and its connection to the NFL and other contact sports?

The Star

29-07-2025

FILE PHOTO: Oversized football helmets surround the convention center as the city hosts Super Bowl LIIV in Miami, Florida, U.S., January 31, 2020. REUTERS/Mike Blake/File Photo
NEW YORK (Reuters) -A gunman who opened fire in a Midtown Manhattan office building on Monday believed he suffered a brain injury that he blamed on the National Football League, New York's mayor said, thrusting the issue of chronic traumatic encephalopathy back into headlines this week.
According to police, Shane Tamura, a 27-year-old former high school football player with a history of mental illness, killed four people with an assault rifle in a Park Avenue office tower that houses NFL headquarters before shooting himself in the chest.
The following is a breakdown of what CTE is and its relationship to contact sports.
WHAT IS CTE?
CTE is a degenerative disease caused by repeated impacts to the head, including both concussive and asymptomatic non-concussive hits. Doctors are only able to make a confirmed diagnosis after death, though common symptoms including aggression and dementia may surface while a patient is living.
WHAT IS THE RELATIONSHIP BETWEEN THE NFL AND CTE?
Research has found a connection between CTE and athletes who have competed in tackle football at both the professional and amateur levels.
The NFL has acknowledged a link between football-related concussions and CTE. In 2015, the league agreed to a roughly $1-billion settlement for concussion-related lawsuits with thousands of retired players after the deaths of some high-profile players.
Boston University's CTE Center diagnosed 345 former NFL players with CTE out of 376 studied, as of 2023.
"If they've been exposed to football for a long time, that increases their risk," Dr. Ann McKee, director of the CTE Center, told Reuters.
DID TAMURA PLAY IN THE NFL?
Tamura did not compete in the NFL, the highest level of professional American football, but played at a Los Angeles charter school until graduating in 2016.
WHAT ARE SOME EXAMPLES OF CTE AMONG FORMER PLAYERS?
Junior Seau, a 12-time Pro Bowl linebacker and Hall of Famer, died by suicide in 2012. A study of his brain later showed he had suffered from CTE, a case that accelerated the national conversation around brain injuries in the NFL.
Former New England Patriots player Aaron Hernandez, who was found guilty of first-degree murder in 2015 and died by suicide in prison in 2017, was found to have pronounced signs of the disease, according to Boston University findings.
Ex-NFL player Phillip Adams gunned down six people and himself in 2021. McKee found he had suffered Stage 2 CTE after examining his brain.
WHAT HAS THE NFL DONE TO MITIGATE BRAIN INJURIES?
Concussions fell to a record low during the most recent NFL season, with the league crediting improvements in helmet technology as well as rule changes for the decline.
Enhanced concussion protocols were implemented in 2022 after the NFL faced intense criticism over head injuries suffered by Miami Dolphins quarterback Tua Tagovailoa.
The league previously banned dangerous helmet-to-helmet hits.
But some researchers, including McKee, have said the measures fall short.
"They have addressed concussion, but that's the tip of the iceberg. The real issue is the asymptomatic hits to the head that don't cause concussion, and there's been very little done to address that," said McKee.
WHAT ABOUT OTHER SPORTS?
Researchers have identified a connection between CTE and other sports, including rugby, ice hockey, and soccer.
A group action in the United Kingdom involves more than 1,000 mostly former rugby players, including many high-profile internationals, who say the sport's governing bodies failed to do enough to protect them from potential brain injuries despite being aware of the risks.
World Rugby, the sport's governing body, has introduced a series of player welfare measures in recent years in an attempt to minimize concussions and head injuriesin the sport.
(Reporting by Amy Tennery in New York, additional reporting by Thomas Rowe and Mitch Phillips; Editing by Frank McGurty and Rod Nickel)