What to know about CTE after NYC shooting suspect appears to target NFL headquarters

The gunman who opened fire in midtown Manhattan on Monday, killing four people before turning the gun on himself, left a note mentioning “CTE” several times, officials familiar with the investigation told NBC News.

The gunman who opened fire in midtown Manhattan on Monday, killing four people before turning the gun on himself, left a note mentioning “CTE” several times, officials familiar with the investigation told NBC News.

CTE, or chronic traumatic encephalopathy, is a brain condition caused by repeated injuries to the head, typically over many years.

The shooter was targeting the headquarters of the NFL, which is in the Park Avenue building where the shooting took place, authorities said.

While CTE can’t be formally diagnosed without an autopsy, one-third of former NFL players suspect they have the disease, according to a 2024 report. The NFL first acknowledged the link between CTE and football in 2016.

Former NFL player Phillip Adams was found to have severe CTE after he gunned down six people before taking his own life in South Carolina in 2021.