Medicare finalized a national coverage policy this week that sharply limits payment for Aduhelm and other Alzheimer’s drugs approved through the Food and Drug Administration’s accelerated-approval pathway, a decision that places evidence generation at the center of access to one of the most controversial new therapies in American medicine.

The Centers for Medicare & Medicaid Services said Thursday that monoclonal antibodies directed against amyloid for Alzheimer’s disease will be covered under a framework known as coverage with evidence development. Under the final national coverage determination, products that receive accelerated approval, including Biogen’s Aduhelm, are covered only for beneficiaries enrolled in qualifying randomized controlled clinical trials conducted under an FDA investigational new drug application or certain NIH-supported studies.

The policy creates a different path for drugs that receive traditional FDA approval based on evidence of clinical benefit. CMS said those products could be covered in a broader range of prospective comparative studies, including some registry-based designs. The agency’s fact sheet describes the distinction as a way to align Medicare coverage with the strength of the evidence supporting each therapy.

Aduhelm forced two federal agencies to answer different questions

The FDA’s job is to decide whether a drug meets the statutory standard for marketing approval. CMS must make a separate determination about whether a service is reasonable and necessary for Medicare beneficiaries. Aduhelm exposed the gap between those roles because the FDA approved the drug through the accelerated pathway while substantial uncertainty remained about whether reducing amyloid plaques would translate into meaningful clinical benefit for patients.

The FDA announced accelerated approval for Aduhelm in June 2021 based on its effect on amyloid beta plaques, a surrogate endpoint the agency judged reasonably likely to predict clinical benefit. The approval required a post-approval confirmatory trial. The National Institute on Aging’s statement at the time noted both the significance of the first new Alzheimer’s treatment approval in nearly two decades and the need for continued research to clarify clinical benefit.

CMS responded by opening a national coverage analysis rather than allowing routine Medicare payment automatically. Its January proposal would have restricted the entire class to randomized clinical trials. After receiving more than 10,000 stakeholder comments and reviewing more than 250 peer-reviewed documents, the agency modified the final policy to distinguish between accelerated and traditional approval.

The policy narrows routine access to Aduhelm

Aduhelm is administered by infusion and is intended for patients with mild cognitive impairment due to Alzheimer’s disease or mild Alzheimer’s dementia, the population studied in clinical trials. Treatment also requires confirmation of amyloid pathology and monitoring for imaging abnormalities that can include swelling or bleeding in the brain.

Under the final Medicare policy, an accelerated-approval drug in this class will not be covered simply because a physician prescribes it to an eligible beneficiary. Coverage is tied to a qualifying trial designed to produce evidence about whether the therapy improves health outcomes. That requirement significantly narrows access because only patients who can enroll at participating research sites will qualify for Medicare payment.

Biogen objected to the final decision. In an April 7 statement, the company argued that the policy denies broad Medicare access to an FDA-approved medicine and could create inequities for patients who live far from clinical-trial sites. Biogen maintains that Aduhelm’s effect on amyloid and the totality of clinical evidence support access while the required confirmatory study proceeds.

The dispute centers on what evidence should trigger payment

The underlying scientific disagreement is not primarily about whether Aduhelm lowers amyloid. It does. The harder question is whether that biological change reliably produces a clinically meaningful slowing of memory loss, cognitive decline or loss of daily function. Aduhelm’s late-stage trials produced conflicting results, and the accelerated-approval pathway allowed the FDA to rely on the surrogate endpoint while requiring future confirmation.

Biogen and Eisai’s original approval announcement emphasized that Aduhelm was the first therapy approved to address a defining pathology of Alzheimer’s disease rather than only its symptoms. That mechanistic advance is scientifically important. CMS, however, is asking a payer’s question: whether Medicare should finance broad use before evidence establishes the degree of patient benefit.

The answer has major fiscal implications because Alzheimer’s disease primarily affects older adults and Medicare would be the dominant payer. Even after Biogen reduced Aduhelm’s list price to about $28,000 per year for a typical patient, widespread use would carry substantial drug, infusion, imaging and monitoring costs. Those costs also affect the Medicare Part B program, whose premiums are partly calculated to cover expected spending.

A broader path remains open for future drugs

The final policy is not a permanent class-wide refusal to cover anti-amyloid therapies. CMS explicitly created a broader evidence-development route for drugs that obtain traditional FDA approval based on direct evidence of clinical benefit. That distinction could become especially important because several companies are developing other monoclonal antibodies targeting amyloid.

If a future product demonstrates a clinically meaningful effect and receives traditional approval, Medicare could cover it through prospective comparative studies or registries that are less restrictive than randomized trials. The policy therefore establishes an incentive structure: the stronger the evidence at approval, the broader the potential Medicare coverage.

This approach also leaves room for CMS to revisit the national determination as the evidence changes. A positive confirmatory trial for an accelerated-approval product could support conversion to traditional approval and a different coverage pathway. Conversely, failure to confirm benefit could weaken the case for continued use.

Patients remain at the center of an unresolved evidence problem

For families facing Alzheimer’s disease, the policy lands in a difficult space between urgency and uncertainty. There is enormous demand for treatments that can alter the course of the disease, and even a modest slowing of decline could be meaningful for some patients. But exposure to treatment risk and substantial public spending are harder to justify when clinical benefit remains uncertain.

CMS has chosen to make evidence generation a condition of payment rather than treating FDA marketing authorization as the end of the inquiry. That decision will restrict access to Aduhelm in the near term and will likely remain controversial among patients, physicians, manufacturers and researchers.

It also establishes a precedent with implications beyond a single drug. For therapies approved on surrogate endpoints in conditions affecting large Medicare populations, federal regulators may increasingly face the same two-part question: is a treatment promising enough to market, and is the evidence strong enough to pay for broadly? With Aduhelm, FDA and CMS have now given different but legally distinct answers.