What to know about CTE, the brain disease that Manhattan shooter claimed to have

The gunman who shot and killed an NYPD officer and three other people in midtown Manhattan on Monday carried a handwritten note claiming he had CTE — a degenerative brain disease that is the result of repetitive hits to the head, officials said.

 Although the disease can only be diagnosed after an autopsy, Shane Tamura, a 27-year-old from Nevada who played high school football, wrote that football "gave me CTE." Here's what to know about the disease.

What is CTE?

CTE stands for chronic traumatic encephalopathy, a brain disease found in athletes, first responders, members of the military and other people who have had a history of repetitive head impacts, according to the CTE Center at Boston University. Examples include heading the ball in soccer and checking in ice hockey. The continuous head impacts cause a progressive degeneration of the brain tissue, according to the center.
"CTE takes many, many years," Dr. Shae Datta, co-director of the NYU Langone Concussion Center in Manhattan said in an interview. "It's going to be after 10-plus years of getting head injury."

What are the symptoms?

CTE cannot be diagnosed until the patient has died and their brain is examined. But doctors said there are symptoms such as changes in cognition, mood and behavior. The American Brain Foundation said they can include difficulty thinking, short- and/or long-term memory loss, depression, anxiety, paranoia, headaches and suicidal thoughts or behavior.

Dr. Ann McKee, director of the CTE Center at Boston University, said that concussions are not associated with CTE.

"That's a very widely held false belief," said McKee, who has done extensive research on CTE. "It's the number of hits to the head ... they don't cause concussion and the player plays right through them as though nothing has happened."

How can it be avoided?

An individual that has sustained multiple hits to the head should stop the activity, Datta said.

"That's the only prevention at this point," she said. "Once you have it, it's not really going to be reversed. It can be treated or managed."

McKee said for every 2.6 years of football, a player's risk for CTE doubles.

"So if you play 10 years of football, you have considerable risk, even if the highest level you only played was high school," she said.

Who has had CTE?

Boxers and people who play ice hockey, football and soccer are at risk for developing CTE. But Datta said it's not just professional athletes.
"CTE has been found in athletes who did not play sports after high school or college," she said.
In 2023, a study of close to 2,000 former NFL players showed that 34% thought they had CTE based on symptoms.
That same year, the Boston University CTE Center said it diagnosed 345 out of 376 dead former NFL players with CTE.

How are schools on Long Island reacting to CTE?

Last year, Newsday surveyed Long Island schools and found 31 were using Guardian Caps — protective padding around the football helmet. The majority, about 72% were not using the caps.
Some coaches have also adjusted the way teams practice.
"We had a change in philosophy to have much less full contact in practice," East Islip football coach Sal J. Ciampi said. "We learned over the past 25 years; we could keep our players safer by limiting full contact in practice. It didn't just reduce head injuries but kept players healthier overall."
Newsday reporter Gregg Sarra contributed to this story.