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A type of PET scan can allow doctors to see amyloid plaques in the brain earlier. Getty Images

Until recently, the only way to determine if someone’s brain had the plaques and tangles indicative of Alzheimer’s disease was to cut it open after they died.

Diagnosing the progressive memory loss disease has instead relied on identifying symptoms of the ailment.

But a new technology may provide doctors with a method to diagnose the disease in some cases.

That technology is currently not covered by health insurers and is too expensive to be used widely, but it’s a big step toward becoming at least a bit more accessible.

In a study published last week, researchers announced that a type of PET scan can tell whether amyloid plaques are in the brain of a living person.

The scan, they said, will allow doctors to change diagnoses or treatment plans for some people.

In amyloid PET imaging, “tracer molecules” stick to the amyloid plaques that disrupt nerve connections in the brain and have been tied to Alzheimer’s.

That allows physicians to see if a person’s brain has the plaques or not. If they do, then they may have Alzheimer’s — although they’ll need further evaluations to decide for sure.

That’s because amyloid is a necessary but not sufficient cause of Alzheimer’s — other factors, such as tau tangles also need to be present.

But if the scan is negative, then doctors can be certain someone doesn’t have Alzheimer’s. If they have memory loss, it’s due to a different cause.

Being able to diagnose Alzheimer’s earlier would be useful in a couple of ways.

It helps both patients and families prepare for further changes in memory and behavior as well as start treatments earlier.

And it helps researchers better study possible treatments and cures since they’d know more about the disease that people in the trials have.

A person suspected of having dementia wouldn’t necessarily be able to get a scan for amyloid plaques anytime soon, though.

Even if the scans do become more available, they’d only be recommended in specific cases, according to Maria Carrillo, chief science officer at the Alzheimer’s Association and a co-author of the new study.

A patient would already need to be showing possible signs of dementia, for instance.

Carrillo told Healthline this wouldn’t be something you could do if you’re just concerned you might get Alzheimer’s because you have a family history of the disease, or a genetic test says you’re predisposed to it.

And she said it wouldn’t be something that could be used like a cancer screening, which you might get every couple of years after a certain age.

But other experts wouldn’t rule that out.

“In a perfect world, it could be like that,” Dr. Ronald Petersen, director of the Mayo Clinic Study of Aging, told Healthline. “It’s premature now, but maybe down the road somewhere.”

However, that might be a ways off, primarily because we’d need to have effective therapies for Alzheimer’s first, Petersen said.

Otherwise, there wouldn’t be enough of a point to providing these scans for most people.

In a perfect world where we have a way of treating or preventing Alzheimer’s though, a diagnostic tool that finds the amyloid plaques as they start to build up could be a game changer.

That’s because there’s a 10- to 15-year lag between when amyloid starts building up and when a person starts showing signs of Alzheimer’s, according to Petersen.

“So we have a window,” he said.

The other reason you likely won’t be able to get an amyloid scan anytime soon is because they’re too expensive.

But the new study may start to change that a bit.

The point of the research was to see whether doing the scan prompted doctors to change their recommendations to patients.

If the scan has that effect, it’s possible Medicaid and private health insurers might cover the scan later on.

Doctors did change their recommendation for more than 60 percent of the people in the study.

In patients whose brains showed plaques, doctors were much more likely to prescribe Alzheimer’s drugs after the scan than they had been before.

In some people who had already been taking Alzheimer’s drugs but whose scans showed no plaques, doctors took them off those meds.

That demonstrates that the scans can change treatment plans.

But the next step is demonstrating that the scans can improve health outcomes, Carrillo said.

To do that, they’ll need a year’s worth of data, showing that the changes doctors made had a positive impact.

If they get that, she said, they’ll go to the Centers for Medicare & Medicaid Services, the government agency that manages the public health insurance plans, with a request that they cover the amyloid scans.

If CMS agrees, the hope would be that private health insurers would begin to cover it, too.

A new PET scan that can tell whether amyloid plaques are in the brains of people who might have Alzheimer’s took a big step toward being more widely available.

Some doctors changed the treatment recommendations or diagnoses of these patients after the scan, a new study found.

That could mean that health insurers might cover the scan in the future.

That could also lead to more accurate detection of Alzheimer’s and possibly a boost in the search for new treatments.