What to Know About Aduhelm, the New Alzheimer's Drug

Promising or problematic? How to make sense of the controversy over Aduhelm.

Phrenology bust Photo: Johanna Parkin/Getty Images

The Food and Drug Administration recently approved aducanumab (Aduhelm), the first new drug for Alzheimer’s disease in almost 20 years—and the first to potentially slow disease progression.

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Some experts consider this a big step, but many disagree with the FDA’s decision, saying there’s little evidence the drug works and is safe. Several major medical centers, including the Cleveland Clinic in Ohio and Mount Sinai Health System in New York City, have opted not to administer Aduhelm to patients at this time.

“It’s an incredible accomplishment for the field that we can use a drug to alter the biology of the disease,” says David Wolk, MD, director of the Alzheimer’s Disease Research Center at the University of Pennsylvania Perelman School of Medicine in Philadelphia. But “there’s still uncertainty about the clinical benefit of the drug, and it has side effects that, in some cases, can result in serious neurological injury.”

The news about Aduhelm may continue to unfold for a while. But for now, here are answers to key questions.

How Does Aduhelm Work?

The drug, given intravenously once a month, signals the immune system to break down amyloid plaques, protein clumps in the brain thought to kill brain cells. In theory, clearing amyloid could slow brain deterioration, though other experimental treatments targeting amyloid haven’t eased Alzheimer’s symptoms.

Does It Reduce Symptoms Well?

That’s uncertain because the two pivotal clinical trials of Aduhelm yielded conflicting results. On average, study participants—people with very mild symptoms of Alzheimer’s disease—scored worse on assessments of memory, problem-solving skills, and function after taking Aduhelm or a placebo for 18 months.

One of the studies found that those given Aduhelm declined more slowly than those in the placebo group; the other found it didn’t help. “At best, the drug slowed down an already slow-moving disease by one-quarter to one-third,” says Wolk, whose medical center participated in the clinical trials.

Who Is Aduhelm For?

It’s approved for people in the early stages of Alzheimer’s. The drug’s questionable clinical benefits in those with very mild symptoms suggest that it’s highly unlikely to help people with moderate to severe cognitive impairment, says Constantine Lyketsos, MD, director of the Memory and Alzheimer’s Treatment Center at Johns Hopkins University School of Medicine in Baltimore.

Are There Possible Side Effects?

In studies, about 40 percent of patients developed brain swelling, sometimes along with tiny brain bleeds. About 1 in 4 people with brain swelling also experienced headaches, confusion, vision changes, or nausea. Other possible side effects include diarrhea and falls, and allergic reactions are possible.

Will Insurance Cover the Cost?

It’s unclear. The Centers for Medicare & Medicaid Services (CMS) is conducting a formal review to decide on a national policy. Some Blue Cross Blue Shield plans have already said they won’t cover it, and other insurers are waiting on the CMS decision.

The price: $56,000 per year for the drug and more for services such as safety monitoring and MRIs. “We’ve worked out that it would cost about $100,000 to treat someone with Aduhelm for a year,” Lyketsos says.

What If You Want to Take Aduhelm?

Talk with your Alzheimer’s disease specialist about whether it might be appropriate. If so, you’ll need cognitive tests and probably a lumbar puncture or positron emission tomography (PET) scan to confirm the presence of brain amyloid.

Because side effect risks may well outweigh potential clinical benefits, ask how your doctor will monitor you for those effects and when you’d need to stop taking the drug, Lyketsos says. And be aware that you may face significant out-of-pocket costs.

Editor’s Note: A version of this article also appeared in the October 2021 issue of Consumer Reports on Health.

Teresa Carr

Teresa Carr is an award-winning journalist with a background in both science and writing, which makes her curious about how the world works and eager to tell you about it. She is a former Consumer Reports editor and 2018 Knight Science Journalism Fellow at MIT and has more than two decades' experience reporting on science, health, and consumer issues.