What is CTE? NYC shooting suspect Shane Tamura claims to suffer from CTE linked to football injuries

NEW YORK - Police are still working to understand why a man drove cross-country with an assault rifle and opened fire inside a Midtown Manhattan high-rise; killing four people, wounding one more, and then taking his own life.

Authorities identified the gunman as 27-year-old Shane Tamura from Las Vegas, Nevada. According to New York City Police Department (NYPD) Commissioner Jessica Tisch, Tamura had a history of mental illness and acted alone. 

Shane Tamura claims to suffer from CTE

What they're saying:

In a video message, Tisch said Tamura left a suicide note and claimed to be suffering from chronic traumatic encephalopathy (CTE), possibly from playing high school football. 

Tamura also blamed the NFL and asked that his brain be studied for signs of the degenerative disease. 

According to the commissioner, he wrote in his note, "Study my brain. I’m sorry," and also mentioned a Frontline documentary from 2013 on the topic. 

Despite his references to football-related brain trauma, officials confirmed Tamura had never played in the NFL. He had played at Granada Hills Charter High School in California and was most recently employed as a casino security guard in Las Vegas.

Video obtained by the Daily News Prep Sports shows a clip of Tamura after a 2015 high school football game where he said the team was down 10-0, and that "we just have to do better as a team."

Among the victims of the Midtown shooting was someone inside the building's NFL offices who is now in critical condition at New York-Presbyterian Hospital.

NFL Commissioner Roger Goodell addressed league employees, urging staff to remain alert and pay close attention to emergency notifications.

What is CTE?

Dig deeper:

According to Cleveland Clinic, CTE is a degenerative brain condition that happens after repeated head injuries. CTE usually affects athletes who play contact sports or military personnel. There’s no cure for CTE, but a healthcare provider may suggest treatments to help the person manage the symptoms they experience.

Why is it associated with the NFL?

After more than a decade of denial, the NFL conceded the link between football and CTE in 2016 testimony before Congress, and has so far paid more than $1.4 billion to retired players to settle concussion-related claims.

The 2015 Will Smith film "Concussion" detailed the pioneering efforts of forensic pathologist Bennet Omalu, whose diagnosis of CTE in Pittsburgh Steelers Hall of Fame center Mike Webster was the first in a former NFL player. Hall of Famers Ken Stabler, Frank Gifford and Junior Seau have also been diagnosed with CTE, as has Aaron Hernandez; in a 2017 paper, evidence of the disease was found 110 of the 111 former NFL players' brains studied.

Symptoms of CTE

CTE shares symptoms with other brain conditions that cause neurodegeneration, according to the clinic.

It can affect a person’s ability to think and remember, their mood and personality, and how they physically move their body.

RELATED: Who is Shane Tamura? NYC shooter reportedly blames NFL, CTE in suicide note

Cleveland Clinic also said it can affect certain mental abilities, including memory loss, solving problems, making choices and mild cognitive impairment.

In addition, neurodegeneration can affect the parts of your brain that control a person’s personality and emotions. A person with CTE may have increased anxiety, depression, mood swings, personality changes or thoughts of self-harm or suicide.

Did Shane Tamura have CTE?

For now, it's not possible to definitely say whether Shane Tamura had CTE, as it can only be diagnosed by examining the brain posthumously through an autopsy. 

Cleveland Clinic said experiencing repeated head injuries causes CTE. Experts are still studying exactly why it happens in some people but not others. But they know having multiple head injuries is one of the most common causes.

People with CTE almost always have a history of repeated head injuries over many years, the clinic said, noting that a person doesn’t have to pass out for a hit to their head to damage their brain. The effects of repeated head impacts build up over time.

Researchers think a buildup of abnormal tau proteins in the brain may also cause CTE. Tau proteins help a person’s cells keep their shape. But if repeated head hits damage a person’s cells, the tau proteins may lose their normal structure.

How the Midtown shooting unfolded

The backstory:

According to the NYPD, Tamura drove his black BMW east from Las Vegas. Over the next three days, his car was tracked through Colorado, Nebraska, and Iowa, reaching Columbia, New Jersey by the afternoon of Monday, July 28.

Around 6:28 p.m., Tamura double-parked his car along Park Avenue and exited with an M4-style assault rifle. Surveillance footage captured him entering the building and immediately shooting NYPD Officer Islam, who was working a security detail in the lobby. He then shot a nearby woman before heading into the elevator.

Tamura proceeded to multiple floors, killing a total of four victims, three civilians and Officer Islam, and critically injuring a fifth, believed to be the NFL employee. He ultimately took the elevator to the 33rd floor, where he shot and killed another person before turning the gun on himself.

Although the office building houses NFL offices, officials believe Tamura may have gone to the wrong floor. 

NYPD Commissioner Tisch explained that the building has multiple elevator banks, and surveillance video shows Tamura entered one that does not reach the NFL’s offices. Instead, he arrived at the offices of Rudin Management, where he opened fire.

"We’re still going through the suicide note to zero in on the exact reason," said Mayor Eric Adams. "But at this time, it appears to be tied to his belief that he experienced CTE from playing in the NFL."

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