Earlier this month, Bill Gates announced his support for Alzheimer’s research. In his five-point research strategy, Mr. Gates wrote: “We need to detect and diagnose Alzheimer’s earlier.” I agree that we need more diagnostic tools for Alzheimer’s, but we also need to use the ones we have.
In 2012, the Food and Drug Administration (FDA) approved Amyvid™, the first diagnostic test for Alzheimer’s disease. And for the first time, doctors could diagnose Alzheimer’s in living patients. This should have been a sea change. Instead, Amyvid™—a PET scan that can detect beta-amyloid plaques in the brain—remains underutilized.
The Centers for Medicare and Medicaid Services denied Medicare reimbursements for the scan in 2013. Most insurers follow Medicare’s lead, so the majority of patients aren’t covered and can’t afford it. Medicare did, however, agree to reimburse use of the beta-amyloid scan in research studies through its Coverage with Evidence Development (CED) program. Unexpected results from these and other studies are shedding light on the scan’s enormous potential.
Improving Patient Care
The most prominent use of CED funding is the IDEAS study, which is exploring how diagnosis with beta-amyloid scans change patient care. (This is an important criterion for Medicare reimbursement.) Interim findings from approximately 4,000 of the 18,000 patients enrolled, all of whom had been diagnosed with either mild cognitive impairment or dementia, were released this year.
The results were shocking—dementia experts had misdiagnosed nearly half of patients with mild cognitive impairment and a third of those with Alzheimer’s disease. Doctors said as a result of the test they would need to change treatment and care for an astounding two-thirds of patients in the study.
Revolutionizing Clinical Trials
Using the scan, we have also discovered that over a third of patients enrolled in previous clinical trials of potential Alzheimer’s drugs didn’t have Alzheimer’s disease. It’s possible that previous trials failed not because a drug didn’t work, but because patients didn’t actually have the beta-amyloid it was designed to remove.
Biogen’s clinical trial of aducanumab was one of the first to enroll all patients using the beta-amyloid scan to ensure everyone has plaques. The scan is also being used to monitor the drug’s efficacy during the trial. So it will be a more accurate test of an anti-amyloid drug for Alzheimer’s disease patients. If beta-amyloid scans were more widely available, it would be easier and faster to enroll the right patients in Alzheimer’s trials and speed up the development of new drugs.
Enabling Prevention
The scan has also revealed that beta-amyloid plaques can begin forming in the brain decades before Alzheimer’s symptoms appear. This provides a window for prevention. A growing body of research, outlined in this year’s National Academies’ report Preventing Cognitive Decline and Dementia: A Way Forward, suggests certain lifestyle choices can protect the brain and lower your Alzheimer’s risk. If you knew in your 40s or 50s that you had beta-amyloid plaques, you could make choices to protect yourself and have enough time to plan for the future. You could also enroll in a clinical trial testing Alzheimer’s prevention drugs, such as the large A4 study.
The amyloid-beta PET scan is no longer available to patients and their health care providers in Europe due to cost issues. It will now only be available for research purposes. (The lack of widespread reimbursement in Europe has forced the manufacturer to discontinue its availability). Without some form of insurance or Medicare coverage, the same could happen in the United States.
The Alzheimer’s Drug Discovery Foundation, where I serve as Chief Science Officer, funded the early development of the Amyvid™ PET scan because we believed in its potential. We knew people with Alzheimer’s were being under-diagnosed and even misdiagnosed. The scan changes all that. But the beta-amyloid PET scan has changed so much more. Imagine what it could do if every patient had access to it.