There’s just one way to make absolutely sure a dementia diagnosis — add an amyloid PET scan on top of existing diagnostic tests. But Medicare and Medicaid won’t pay for it.
Now that lecanemab is approved by the Food and Drug Administration (FDA) and reimbursed by Medicare and on the market as Leqembi, many Americans still won’t be able to afford the disease-modifying Alzheimer’s treatment.
Do you need a PET scan to diagnose Alzheimer’s?
While a dementia diagnosis involves considering a patient’s history, and a battery of cognitive tests, there are ultimately only two reliable ways to go from cognitive symptoms to a definitive Alzheimer’s diagnosis: looking for the presence of the disease’s key biomarker — beta-amyloid plaques in the brain — via a lumbar puncture or a PET scan, or a brain scan performed with positron emission tomography technology.
According to a 2020 Lancet study, approximately 35 percent of patients — those refusing or unable to undergo a lumbar puncture, and those with ambiguous symptoms — need an amyloid PET scan to receive a diagnosis.
Lumbar punctures survey the fluid bathing the brain and spinal cord, called the cerebrospinal fluid (CSF), looks for fragments of brain plaques. PET scans involve injecting a safe radioactive marker into the bloodstream that binds to amyloid plaques in the brain. When the brain is scanned, these plaques “light up”. If someone receives a lumbar puncture and a PET scan, it is likely that the results will agree with each other. Sometimes, a PET scan however provides extra information that could correct a faulty diagnosis.
While lumbar punctures are covered by insurance, the Centers for Medicare and Medicaid Services — the agency that decides what Medicare and Medicaid will cover — has refused general widespread federal insurance coverage of amyloid PET scans.
However, some doctors do still request that a PET scan be performed after a lumbar puncture, in cases where the results appear abnormal, and they want an additional set of data to confirm their diagnosis.
For people on Medicare or Medicaid, this can mean a big medical bill. Medicare only provides coverage for one amyloid PET scan per patient in a lifetime within the context of a clinical trial. The CMS is currently revisiting this decision, potentially expanding it to two scans in clinical trials. Just under 40 percent of American patients rely on Medicare or Medicaid for their health insurance, and outside of clinical trials these Americans are paying out of pocket for PET scans at thousands of dollars per procedure. Many insurers have made decisions concordant with Medicare, denying coverage for these diagnostics.
Is the CMS following the evidence on amyloid PET scans for dementia?
The CMS initially refused widespread coverage for these diagnostics because there is insufficient evidence that imaging is “reasonable and necessary for the diagnosis or treatment” of neurodegenerative diseases.
The 2019 IDEAS study that followed over 11,000 people with cognitive impairment showed that PET scans led to improved disease management for 60 percent of people, while also helping to correct misdiagnoses.
According to Gil Rabinovici, the first author on the IDEAS study and a professor at the UCSF Memory and Aging Center, their study showed that amyloid PET scans reduced hospitalization by 4.5 percent and provided a better diagnosis to 30 percent of the participants.
Normally, for Medicare to cover a diagnostic, research must show that it can reduce hospitalizations or mortality by certain benchmarks. These make sense when it comes to measuring diagnostics for cancer and cardiology, Rabinovici said, but they are not very useful criteria for assessing PET scans in Alzheimer’s. They diagnose a long progressive disease at the earliest stages, he pointed out — meaning it would typically be years or even decades before dementia–related hospitalization or mortality.
Why is an accurate dementia diagnosis important?
While the CMS denied general coverage of PET scans because they aren’t convinced it is “reasonable and necessary for [dementia] diagnosis or treatment.” But they wrote that PET scans were promising in two scenarios: “to exclude Alzheimer’s disease (AD) in narrowly defined and clinically difficult differential diagnoses, such as AD versus frontotemporal dementia” and for selecting patients for clinical trials.
This ability to differentiate between dementia’s many different types is a critical advantage, when one in four patients living with dementia has been misdiagnosed.
There are many types of dementia that are difficult to distinguish from Alzheimer’s disease. Lewy body dementia is misdiagnosed 80 percent of the time, often mistaken for Alzheimer’s because the early symptoms are similar. If a lumbar puncture is looking for signs of beta-amyloid, they may well find it in these patients.
A misdiagnosis can have dire consequences. It means a patient isn’t getting access to the targeted care available for their particular disease. Meanwhile, they may be getting treatment for a disease they don’t have — and that can be dangerous. For example, while antipsychotic drugs are commonly prescribed for people with Alzheimer’s, they can cause adverse reactions in people with Lewy body dementia.
Advocates and scientists: CMS decision needs a rethink
These risks considered, advocates and scientists have spoken up to say the CMS decision not to cover PET scans is unethical.
During a 2022 comment period on the agency’s decision not to cover PET scans for people with dementia, William T. Thorwarth, CEO of the American College for Radiology, wrote a letter on behalf of more than 40,000 radiologists urging the CMS to reconsider their decision, and calling on them to provide national coverage for use in diagnosis and monitoring during treatment.
“Beyond the IDEAS study, at least 30 published studies involving more than 4,000 patients have reviewed the utility of beta-amyloid imaging for the diagnostic assessment of patients evaluated for cognitive impairment in memory clinics,” Thorwarth wrote, “Beta amyloid PET contributes to diagnostic revisions in approximately 30 percent of patients,” he added, so without access to a PET scan, a large number of patients don’t have access to an accurate diagnosis.
Right now, the only study qualified for amyloid PET scan coverage under Medicare are those that enroll in the New IDEAS trial which is set to test whether the scans are effective in a more ethnically diverse minority population. The trial has now only enrolled at 15 of its original 125 clinical trial sites because Medicare is only covering the PET scan and not the markers that are used to tag amyloid in the brain. Trial centers are refusing to enroll because they would be set to incur a financial loss from paying for the markers.
No federal insurance for PET scans will ‘deepen health disparities’ for women and minorities
People who can’t afford to pay thousands per scan may go into debt or miss out on amyloid PET scans resulting in misdiagnosis and its aforementioned disadvantages and risks. During the course of a treatment or therapy, the lack of a PET scan would make it more difficult to assess how well the treatment is working.
Alzheimer’s advocates worry this refusal to cover a key procedure in dementia diagnosis and care for the low-income and/or aging Americans on CMS insurance programs could deepen existing racial and socioeconomic inequities in brain health treatment.
One advocate who has been outspoken about this is Jim Taylor, who acts as a care partner for his wife Geri.
“This lack of coverage will only deepen health disparities faced by women, those in minority groups, and low-income individuals,” Taylor wrote in a 2021 STAT opinion piece.
Black and Hispanic Americans are already at an elevated risk of developing the disease. And yet, research shows these groups are typically the last to get accurately diagnosed. Groups like Voices Against Alzheimer’s, US Against Alzheimer’s and the American College for Radiologists have called this decision discriminatory or inequitable. They cosigned a letter alongside other advocacy organizations challenging these coverage restrictions.
“Our organizations caution CMS not to inadvertently contribute to, and exacerbate, the massive racial and ethnic inequalities in access to Alzheimer’s disease detection and treatment,” the letter said. “We strongly urge CMS not to use ‘lack of evidence on minority populations’ as part of the rationale to continue a coverage policy that restricts access to those very same populations who have the highest need.”
The takeaway on Medicare coverage of PET scans for Alzheimer’s and dementia
In the near future, Rabinovici says, the development of blood test diagnostics “will make biomarker testing scalable and affordable.” Even then, he believes that PET scans will be required in some cases for diagnosing patients.
Despite new blood, machine learning, and cognitive tests coming down the pipeline, diagnosing Alzheimer’s accurately might remain a challenge. That’s because no one test can diagnose the disease. Multiple different puzzle pieces — patient history, symptoms, and biomarkers — are required to get the full picture because there are overlapping features across different types of dementia.
“As science advances potential treatments for Alzheimer’s disease, we owe it to people with this disabling condition to make sure diagnostic coverage and payment policies also advance,” Taylor wrote.
Re: CMS refusing to cover PET scans, the scans are expensive and Medicare is losing money with Medicare Advantage plans. Perhaps the CEOs of those companies that are overbilling Medicare could pay for said scans out of their ill-gotten gains.
I apologize for my crankiness. I’ve had 3 family members with Alzheimer’s.