What is CTE? All about brain disease New York Shooting gunman Shane Tamura claimed he was suffering from

The 27-year-old suspected gunman behind the deadly shooting at 345 Park Avenue in Midtown Manhattan reportedly left behind a multi-page suicide note pointing to chronic traumatic encephalopathy (CTE) as a key factor in his actions.

Shane D. Tamura, a former athlete, shot and killed four people — including a New York police officer — before turning the gun on himself on the 33rd floor of the 44-storey skyscraper on Monday. The building also houses the headquarters of the National Football League (NFL), which authorities believe Tamura deliberately targeted.

According to the New York Post, the note refers to his mental health struggles and links them to his past involvement in football. He reportedly blamed the sport for causing his CTE, a brain disease associated with repeated head injuries.

The note, cited by CNN, read: “Football gave me CTE and it caused me to drink a gallon of antifreeze. You can’t go against the NFL; they’ll squash you.” Tamura also requested that his brain be studied after death, referencing former Pittsburgh Steelers player Terry Long, who also suffered from CTE and died by suicide in 2006.

CTE has been most commonly observed in athletes involved in contact sports such as American football, boxing, and hockey, as well as military veterans exposed to blast injuries. The condition typically develops years after repeated head trauma and worsens over time.

Tamura, 27, has been identified as the prime suspect in the Manhattan shooting that claimed the lives of four people, including NYPD officer Didarul Islam, and left one person injured. Authorities confirmed that Tamura died by suicide following the attack.