What is CTE, the brain condition referenced by Midtown Manhattan shooter Shane Tamura?

CBS News

3 days ago

Shane Tamura, the gunman in Monday's deadly Midtown Manhattan shooting, wrote about the brain disease CTE in a note obtained by investigators.
New York City Mayor Eric Adams told CBS News that Tamura's note included reference to CTE and the NFL.
"The note alluded to that he felt he had CTE, a known brain injury for those who participate in contact sports. He appeared to have blamed the NFL for his injury," Adams said.
Though Tamura never played in the NFL, investigators believe that the shooter may have been targeting the NFL offices inside the office building where he killed four people.
The three-page note found in Tamura's pocket said that he wanted to have his brain donated to science so it could be researched, according to law enforcement sources.
It is unknown at this time if Tamura had CTE; it can only be diagnosed post-mortem. New York Police Commissioner Jessica Tisch said that Las Vegas law enforcement confirmed Tamura had a history of mental health issues.
Chronic traumatic encephalopathy, or CTE, is a brain disease that is most common in athletes who play contact sports, such as football players, ice hockey players and boxers. It is a degenerative disease, occurring after repeated head injuries cause cells in the brain to die.
Dr. Anne McKee, the director of the CTE Center at Boston University, said while CTE is most talked about in professional athletes, it has also been found in student-athletes.
Tamura played high school football in California in 2014, according to articles from the Santa Clarita Valley Signal.
"Being a high school football player is certainly a possibility for CTE," Dr. McKee said. "We have a recent study where we found about 30% of former high school players had CTE. Now that's a very select group of people. It doesn't mean 30% of the general population of high school football players have CTE, but it's a distinct possibility."
She said that CTE can occur without someone receiving a concussion, but rather, "It's the hits that don't cause any symptoms, the hits that we consider minor hits that the player plays right through, asymptomatic hits, but those hits can be very substantial."
CTE, she explained, has four stages of progression.
"Nerve cells are probably being lost with most of these hits. There's tremendous inflammation. There's vascular changes. So even though the hits stop, the injury to the brain persists, and it doesn't recover, especially if they're getting repeated hits in a short amount of time, so the brain isn't allowed to recover," Dr. McKee said.
"It sets up a situation where there's a vicious cycle inside the brain where you've got inflammation, vascular change, changes to the nerve cells and eventually tau deposition, which goes on, even though the trauma, the hits to the head, have stopped."
Tau is an abnormal protein, which, when built up, can be also be a marker of Alzheimer's disease. Currently, the only way to detect CTE is to stain the proteins during an autopsy of brain tissue, which is complex and can take several months.
"I just think this is an urgent call for us to do something as a society about the risk for CTE that's experienced by amateur contact sport players. It's not just the professional athletes. It's the high school players and the college players who are also at risk and that's where we need to address the real changes in the games," Dr. McKee said.
Irritability, inattention, and behavioral changes such as aggression or impulsivity are common first indicators of CTE, according to Dr. McKee.
The damage "usually begins in small spots in the frontal lobes," she explained. "But over time, with aging, it starts affecting widespread regions of the brain and can cause profound memory loss and even dementia."
Symptoms of CTE do not typically appear right after someone receives a head injury, but rather develop as time goes on, according to the Mayo Clinic. The hospital says additional symptoms of CTE can include trouble thinking and planning, mood changes, suicidal thoughts and substance misuse. Patients may also have trouble with balance and walking, and may develop shaking and trouble speaking.
"We have seen individuals with CTE that have had substantial breaks with reality," Dr. McKee added. "There's precedence where a former football player has a break of homicidal violence and this kind of behavior is obviously something we need to prevent."
CTE has become more talked about in recent years as more cases of the disease are found in former NFL players. Aaron Hernandez, a former New England Patriots player and convicted murderer, was diagnosed with stage 3 CTE after his death. Dr. McKee said at the time that he had one of the worst cases of the disease she had ever seen.
Former NFL player and CBS Sports analyst Irv Cross was diagnosed with stage 4 CTE. His widow said that at the time of his death, he was seeing things.
The BU CTE Center said that out of 376 former NFL players it has tested, 345 had CTE.
The NFL has made changes in recent years to prevent head injuries, including new rules and equipment.
"The NFL has definitely made rule changes to the play of the game that make the game safer for the players, but they haven't done enough, and they really set the stage for all high school and even college football players," Dr. McKee said.
In 2024, the league announced that it will allow players to wear special head protection called Guardian Caps to give more protection against head injuries. Guardian Caps are soft coverings that wrap around the NFL hard-shell helmets, reducing the impact from head injuries.
The NFL also changed kickoffs to reduce full-speed tackles. But Dr. McKee said she believes the organization should be doing more.
"They need to do much more than just the helmet design, which is never going to prevent CTE. It's really rules of play and styles of play, eliminating the hits to the head that occur in practice as well as games, paying attention to the players, monitoring the players for the number of hits they've sustained and actually keep track of the players over time," she said.Pat Milton
contributed to this report.