Putting new Alzheimer's test in context

What I didn't see in news coverage

A scientific paper published in the journal Nature Medicine reports study results that “suggest” that a newly-developed test “may be useful” in improving the diagnosis of Alzheimer’s disease and in monitoring how some drug therapies are working in clinical trials. The authors are careful to conclude, in the study limitations discussion:

This new plasma biomarker should also be further validated in larger and even more real-world populations.

Clearly, this is a research tool to be used in clinical trials for possibly a long time.

But that quickly was communicated as a “breakthrough” by the 1440 newsletter, whose methods I have questioned

. The Guardian quoted a researcher who was not involved in the work, and who called it “very promising and important.” But that expert went on to say that it was not a foolproof blood test for Alzheimer’s.

“This is also not a simple test, rather requiring complex scientific methods only available in specialist laboratories, so this will not be routinely available without further validation and development of cheaper, easier detection,” she said.

That is an important caveat.

But the Guardian didn’t mention that two of the researchers had founded a diagnostic company that developed the test in question. Four of the researchers may receive income based on technology licensed by Washington University to that company. These and other disclosures are made in the paper in Nature Medicine. I am always amazed when journalists do not cite the limitations addressed in the scientific paper, nor the conflicts of interest.

A TIME magazine story headline predicted what the test “might” predict.

But TIME’s story began, as other stories did, with this framing:

With two new treatments for Alzheimer’s disease approved in recent years, there’s growing hope for people at risk of the memory-robbing condition. But tests to detect the condition still lag behind. Earlier diagnosis would mean that people could take advantage of the drugs sooner, when the medicines are most effective.

NPR used that same framing:

“could help doctors identify patients who are likely to benefit from drugs.”

NPR also did not mention the financial disclosures of the researchers.

Those new drugs are lecanemab (Leqembi) and donanemab (Kinsula). Both are approved in the U.S., but with a black box warning for swelling and bleeding of the brain.

But a key question is: will this test help identify people who may “benefit” from the currently approved Alzheimer’s drugs? That depends on what you mean by “benefit” which is a contested topic right now.

It’s important for readers to know that recently the British National Institute for Health and Care Excellence (NICE) declined to recommend both drugs. Just last week the European Medicine Agency decided against approving donanemab, citing that the risks did not outweigh the benefits. None of the stories that I read about the new test mentioned this important context.

A Viewpoint article in the journal JAMA Internal Med in 2023 focused on lecanemab, showing that it was not any better than other long-approved drugs.

In a nutshell, the article concluded that the new drugs can show statistical improvement on memory and other cognitive tests but that really didn’t make a difference in day-to-day living. And the article cited harms such as:

Over 18 months, those taking the dose of lecanemab approved by the FDA had an average of 28% greater loss of brain volume than those taking placebo.

And costs:

When administered at the recommended dosage of 10 mg/kg once every 2 weeks, the annual cost of lecanemab is about $26 500 a year. The cost of the drug does not include the costs of administering the medication; monitoring for potential adverse effects, such as with baseline and periodic brain magnetic resonance imagery; and treatments for adverse effects.

... A recent report estimated that lecanemab and associated ancillary services could add $2 to $5 billion annually to Medicare spending, with substantial out-of-pocket costs for beneficiaries lacking supplemental coverage.

All of which is important to know and to remember if you’re going to frame the excitement over the new test in the context of how it may lead people to new Alzheimer’s drugs more quickly.

These are the things I didn’t see in news coverage of the new test. And I don’t think the news coverage is complete - or entirely balanced - without such analysis.

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