Gunman Blamed Football and CTE in NYC Shooting: What Science Actually Says

A shooting with multiple fatalities took place Monday at a New York City office building, unexpectedly drawing new attention to the complex science of traumatic brain injury and chronic traumatic encephalopathy (CTE), a condition associated with repeated traumatic brain injury. 

Here’s what happened

Police say the shooter, 27-year-old Shane Devon Tamura, opened fire on an upper floor of a building on Manhattan’s Park Avenue, killing four people. Tamura died by suicide. 

Officials confirmed that the shooter had intended to target the offices of the National Football League, but took the wrong elevator and opened fire elsewhere in the building.

Tamura was a former high school football player. Authorities reportedly found a handwritten note in Tamura’s possession in which he blamed football for causing damage to his brain and expressed that he believed he had CTE. 

What’s CTE? 

Chronic traumatic encephalopathy is a degenerative brain condition linked to repeated head trauma that leads to thinking, mood, and behavioral problems. It has been documented primarily in athletes — especially football players, boxers, and hockey players — as well as military veterans exposed to blast injuries. The disease is defined by a build-up of abnormal tau proteins in specific areas of the brain, notably deep within the cortical sulci, grooves in the cerebral cortex, the brain’s outermost region. Other features of CTE in the brain include protein plaques like TDP-43 and Lewy bodies, as well as neuroinflammation. Research shows that CTE is rare and not well understood. 

Because CTE can only be officially diagnosed post-mortem, with an autopsy of brain tissue, Tamura asked in his note for his brain to be studied.

“Study my brain please,” he wrote. “I’m sorry.” 

In his letter, Tamura also referenced former NFL player Terry Long, who died by suicide and was later revealed to have CTE: “Terry Long football gave me CTE,” Tamura wrote, “and it caused me to drink a gallon of antifreeze.”

Long’s CTE was not an outlier: In a Boston University study on CTE that looked across data from just over 200 players’ brain autopsies, more than 99 percent of the 111 NFL players among the test group were found to have CTE. 

While research is under way, there is no direct way to treat CTE, though some medications might help with behavioral symptoms. 

What does CTE have to do with this story?

Without a post-mortem microscopic analysis of Tamura’s brain tissue, it’s impossible to know if he actually was living with CTE. As of this writing, officials have not confirmed whether Tamura’s brain will undergo specialized testing for CTE. The New York City Medical Examiner has initiated a standard autopsy and has not committed to anything further.  

If an autopsy were to find evidence of CTE, neurologists say, that would not necessarily explain an act of violence: The presence of CTE pathology does not guarantee that a person experienced neurological or psychiatric symptoms during life. “The connections between CTE, suicide, and violence are not well understood,” cautioned Michael L. Alosco, a neuropsychologist at the Boston University CTE Center. “We need to remember that the causes of these tragedies are never just one factor.”

As to whether people with dementia can commit acts of violence due to their condition: Like with other neurodegenerative diseases, dementia may bring behavioral symptoms. “Some people go through a phase where they get very agitated, and they can be violent,” Khalid Iqbal, the New York State Institute professor credited with the discovery of tau protein, told Being Patient on the conference floor at AAIC 2025. However, not everyone with dementia develops these symptoms. Not everyone who plays football develops CTE dementia. And again, it’s not yet known whether Tamura had CTE.

Alosco at Boston University added, “The connection between high school football and CTE risk is also unclear. This tragedy does shine a light on mental illness — and mental illness, if caught and detected early, can be managed, and we encourage families and people to seek help.”

So, can football — including high school football — lead to CTE?

Studies have found that repeated concussions — subconcussive impacts in particular — may increase the risk of developing CTE. The dementia that accompanies CTE can, in turn, lead to behavioral symptoms including agitation and aggression. But the threshold of risk — how many concussions the brain can withstand before this long-term damage sets in — is still unknown. 

Most people who experience a concussion recover fully, and not all people with repeated brain injuries go on to develop CTE, according to Dr. Munro Cullum, a neuropsychologist who studies traumatic brain injury. 

“There is a subset — 10 to 20 percent — that continue to report and experience unusual symptoms that last beyond the typical recovery window,” Cullum told Being Patient in a Live Talk. He emphasized that these long-term symptoms remain under investigation, and that no two cases are alike. “The saying in the field is: ‘If you’ve seen one concussion, you’ve seen one concussion.’”

While the exact prevalence of traumatic brain injury and concussions in high school football players is unknown, researchers have found that the average player takes 652 head impacts per 14-week season, raising the risk of future complications. At the professional level, up to one in three professional players believed they had developed CTE.  

Former players, advocacy groups, and even a congressional committee have accused the NFL of attempting to influence or suppress research into the link between the sport and CTE. Several NFL players have sued the league, accusing it of minimizing the risks of head trauma. Under a 2014 settlement between the league and the players’ association, the NFL agreed to financially compensate players who develop cognitive impairment. 

The NFL has also responded by developing new rules, adopting new helmets, and implementing a five-point protocol to ensure players don’t return to the game with a concussion.

Tamura’s case remains under active investigation by the NYPD and the Manhattan District Attorney. Public health experts are urging caution in drawing conclusions about the role of CTE until full medical findings are available.