Earlier this year, former U.S. women’s soccer player Brandi Chastain announced that she will be leaving her brain to Boston University’s brain bank, a collection used to research chronic traumatic encephalopathy (CTE).

Although Chastain isn’t experiencing CTE symptoms currently, she’s in a high risk group.

Athletes and others who sustain repeated trauma to the head — from heading the ball into a soccer net, for example — are among those in danger of developing the condition, which can lead to emotional instability, depression, memory loss, and other cognitive symptoms.

If Chastain were experiencing such symptoms and wanted to get checked out today, she’d have a hard time getting a diagnosis.

Although physicians can suspect CTE, they can’t confirm it without seeing characteristic tangles of tau protein in the brain, something that can only be done with an autopsy.

But there might be another way, according to a team of researchers based at Mount Sinai Health System in New York.

In a paper published today in the journal , the team says they were able to tag and image the protein tangles in the brain of a living patient with suspected CTE.

Read more: Risk of brain injury in BMX and other action sports »

Radioactive technology

The researchers did it by injecting a radioactive chemical into a 39-year-old former National Football League (NFL) player and then imaging his brain with a PET scan.

The misbehaving proteins lit up on the scan.

It’s not the first time tau protein has been tagged and imaged, and it’s not even the first time scientists have claimed to diagnose CTE in a living person.

But it is the first time, says Dr. Sam Gandy, a neurologist at Mount Sinai and co-author of the study, that scientists have imaged the specific pattern of tau protein buildup that occurs in the brain of someone with this condition.

“Whenever the tau occurs at the bottom of the wrinkles on the top of brain or traces along those wrinkles, that means CTE,” he told Dr.China.

Neuroscientists agreed on that definition last year, when CTE experts met in Boston to review slides and case reports of those diagnosed with the condition after death.

CTE looks different in the brain, they decided, from other diseases characterized by tangled tau proteins. Patients with Alzheimer’s disease have these tangles, too, along with plaque buildup, but in different parts of the brain than people with CTE.

It’s a major development to be able to correlate the disease’s symptoms to its pathology, Gandy said.

Read more: Super bowl QB Troy Aikman discusses concussions, melanoma »

Behavior and symptoms

For those whose autopsies have revealed CTE, matching symptoms to the disease relies on memories of the patient’s behavior.

The former NFL player studied by Gandy and his team, who has chosen to remain anonymous, suffered 22 concussions over an 11-year NFL career.

He has complained of irritability, moodiness, difficulty concentrating, headaches, and memory loss.

The highest profile CTE cases have concerned professional football players like him. And the NFL’s response to allegations about the dangers of concussions generated a lot of media attention, and inspired the movie “,” starring Will Smith.

But concern over the long-term effect of concussions is not limited to professional athletes.

Some parents have chosen to keep their kids out of football altogether.

“There is probably more of a chance of seeing one of [my kids] seriously injured from playing football than from playing almost any other sport,” Serge Bielanko, a blogger on the parenting website Fatherly. Bielanko forbade his young son from signing up for football.

Even professional athletes are questioning the wisdom of putting kids in sports.

“I cannot in good conscience allow my grandson to play knowing what I know,” Harry Carson, a former linebacker for the New York Giants, told .

Chastain, too, advocates keeping children under the age of 14 from heading soccer balls.

Others feel that the risk can be managed, and the NFL has revised its on responding to concussions.

Read more: What’s the likelihood a high school football player will get injured? »

Drug on the horizon?

One of the things that makes CTE so scary is that it appears to be irreversible.

But there is some hope.

The doctors at Mount Sinai plan to use their technique to identify patients with CTE who will then participate in an upcoming clinical trial of a new drug that may help repair some of the damage caused by wayward tau.

The drug, which is produced by Cortice Biosciences, is a taxol, a type of drug typically used to treat cancers. Taxols stabilize parts of the cells’ inner skeleton known as microtubules, making it harder for cancer cells to divide unchecked.

But George Farmer, the company’s chief executive officer, told Dr.China that stabilizing microtubules might also help patients with CTE.

Healthy tau proteins coat microtubules and keep them lined up like “railroad tracks” that transport material between brain cells. When tau gets tangled up, the tracks break down and cargo derails.

In addition to fixing the tracks, the drug also seems to help clear out bad tau, Farmer said, although it’s unclear how.

“That whole mechanism is still being figured out,” he said.

So far, the benefits have only been shown in mouse models.

Clinical trials testing the drug’s effect on patients with other tau-associated neurodegenerative diseases like and are ongoing at the University of California, San Francisco.

Gandy said his team plans to test the drug in veterans who have been exposed to IEDs, among others who have suffered head traumas.

Their trial is expected to begin next year.