Behind the race to detect — and treat — brain-disease CTE before it kills

The gunman who unleashed chaos in a Midtown Manhattan skyscraper this summer is a stark reminder of how little we know about a devastating brain disease typically associated with NFL players — which can only be definitively diagnosed after death.

Shane Tamura targeted the league’s Park Avenue headquarters, murdering NYPD Officer Didarul Islam and three bystanders before killing himself.

His suicide note said chronic traumatic encephalopathy “destroyed his mind” after years of football head injuries.

The 27-year-old hadn’t played the sport since high school — but New York City’s chief medical examiner declared last month it found in his brain “unambiguous diagnostic evidence” of CTE, a degenerative disease that can lead to violent mood swings, suicidal thoughts and dementia.

Experts caution the diagnosis doesn’t prove CTE caused the tragedy.

“It could be a factor. But did this happen strictly due to this gentleman having CTE? Probably not,” Dr. Brent Masel, University of Texas Medical Branch at Galveston neurology professor, tells The Post.

And “the presence of abnormalities on autopsies like this doesn’t necessarily mean that the patient has the syndrome.”

CTE’s effects do vary wildly.

Some sufferers struggle with depression, anxiety and memory loss but never display violent tendencies.

Others have unexplainable bouts of anger.

“My husband’s temper is a little quick sometimes, very volatile, to the extent that he will jump to cussing at people,” says Molly, a West Coast woman whose husband is 30 years old and has been diagnosed with probable stage 2 CTE.

“We have young children, and they know their dad had a head injury and about his headaches and memory lapses. I’m pretty good at catching it, so I just tell the kids, ‘Dad’s having a headache, and we’re going to leave Dad alone because he’s not in a good mood.’”

Molly, who asked The Post to conceal her last name for fear revealing her husband’s condition would hurt his employment, says he sustained such a large number of concussions as a high-school football player and wrestler, “He doesn’t even know how many.”

He suffered from debilitating migraines for years, but it was when Molly noticed signs of memory loss that she urged her husband to see a doctor.

A neurologist diagnosed him with probable CTE when he was only 19 years old.

The couple had just watched the 2015 Will Smith film “Concussion,” about Dr. Bennet Omalu’s battle to get the NFL to acknowledge CTE’s effects on its players.

“My husband was in tears watching it. He said, ‘Wow, somebody actually verbalized what I feel and how I experience life every single day.’”

It’s a situation painfully familiar to Eleanor Perfetto.

Her late husband, Ralph Wenzel, suffered a string of concussions during his eight-year NFL career playing for the Pittsburgh Steelers and San Diego Chargers.

He was diagnosed with early onset dementia in 1995 at age 56.

By the time he died in 2012, he was unable to care for himself or even communicate. After his brain was examined following his death, it was confirmed he had CTE.

Wenzel’s struggles helped call attention to the long-term health risks of pro football, especially brain injuries.

“Back in the ’90s, there was so little information. It wasn’t called CTE,” Perfetto, a member of the Brain Injury Association of America, tells The Post.

“We knew things were happening with him, but we didn’t really know what was going on.”

Even now, scientists studying CTE are hamstrung because the disease can only be diagnosed by examining a dead patient’s brain under a microscope.

It’s a challenge Dr. Michael Alosco, a Boston University School of Medicine neurology professor, is tackling as part of an ambitious new study funded by a $15 million grant from the National Institutes of Health.

Researchers at Boston University’s world-renowned CTE Center are leading the project, one of the most significant steps yet to better understand and treat CTE.

“The whole goal is to develop [biomarkers] that can detect it while people are still alive,” Alosco tells The Post.

Biomarkers are measurable biological changes that could show CTE’s signature.

Certain biomarkers are already able to pinpoint the amyloid protein prevalent in Alzheimer’s disease development.

The breakthrough for developing a CTE test in the living, Alosco says, is discovering a similar biomarker that detects tau protein, found in the brain’s nerve cells.

BU is working with the Brain Health Imaging Center at the Center for Addiction and Mental Health, Canada’s largest-mental health teaching hospital.

CAMH researchers use positron emission tomography, a process in which a molecule is made radioactive and injected into the body to get functional imaging.

“Our goal is to develop new brain-imaging agents to try to detect CTE in life,” says Dr. Neil Vasdev, CAMH’s Brain Health Imaging Center director.

“We want to be the first lab in the world to detect a living person.

“If we can detect CTE in the living human brain at early stages, like stage 1 for example,” Vasdev tells The Post, “preventative measures and treatment strategies can be considered.”

Molly believes a detection discovery would raise CTE awareness.

“No one’s going to give credibility to an invisible disease, to something that they don’t think is real or doesn’t exist,” she says.

“But the second step is coming up with ways for people to live with it and cope and see the warning signs as they come on, just like people with seizures have learned to anticipate a seizure and set themselves up to be safe.”

“This disease doesn’t just happen to the individual,” Perfetto notes. “It happens to everyone around them.”

A CTE test for the living could help families plan for an uncertain future.

“It can provide some peace of mind if they get a diagnosis early,” Perfetto says. “Families can make plans, financial plans, and all of those kinds of things that they need to start thinking about early.”

The real breakthrough could be finding specific treatment protocols.

“Because even if you do come up with an all-encompassing test, the next problem presents itself, which is: What do we do now that we know this?” says Dr. Shae Datta, NYU Langone Health’s Concussion Center co-director.

A test “doesn’t resolve the problem; it just identifies it.“

Molly worries about what the future holds for her family.

“There’s definitely times where we’ll get into a fight, and [later] he has no idea what we fought about or what he said. But I remember it, and I have to try to just push that aside and keep going,” she says.

“It has me wondering, ‘Is this going to get worse, are we managing it well enough?’”

BU’s CTE Center, led by Dr. Ann McKee, has been the epicenter of research into the disease since 2008.

Its secret weapon is the world’s largest CTE brain bank: more than 1,500 donated brains, many from ex-NFL players, boxers, military veterans and others who endured repetitive head trauma.

The brain bank has been key to defining exactly what CTE looks like — a distinctive pattern of tau protein tangles that spread through certain regions of the brain, wreaking havoc on memory, mood and impulse control.

While experts have learned much about CTE in the past decade by studying deceased football players’ brain tissue, they agree they need a deeper pool of patient research.

“Almost everything we know about CTE is restricted because it’s based on data from males and from American football players,” notes Vasdev.

“We have to study both males and females. No two head injuries are the same, and the way people respond to head injuries is also different.”

CTE awareness has exploded in the last 10 years.

The NFL has changed protocols for head injuries and toughened rules on helmet-to-helmet hits in response to on-field concussions suffered by NFL stars like Miami Dolphins quarterback Tua Tagovailoa.

Now there’s hope a CTE test for the living is within reach.

“I think in the next five years, we will be pretty confident in terms of our diagnostic abilities and be able to build on that knowledge,” Masel says.

“And then use that to hopefully come up with something to diagnose and perhaps even treat the symptoms.”

Any type of progress in fighting CTE is welcomed by Perfetto, who saw it ravage her husband in his later years.

More than a decade since his passing, she’s thankful to have memories of happier times, before the disease took hold.

“At this point in my life, I remember the good times best,” she says. “And that’s the way I want it.”