Scanning for Alzheimer’s Disease Has Benefits, But They’re Not What You Think

An op-ed in the New York Times by oncologist Ezekiel J. Emanuel provided that welcome blend of empathy – he worries about being stricken by that evil disease Alzheimer’s as much as anyone – and insight – as a cancer doc, he provides a scientific context for our concern.

Emanuel worries if his elderly parents’ forgetfulness is a sign of Alzheimer’s or just age-appropriate behavior. He understands our fear for ourselves and our loved ones over a disease that steals identity, sense of self and independence, and he understands its social toll.

Since 1980, Emanuel says, the number of people with Alzheimer’s-induced dementia has doubled; according to some estimates, in the next 40 years, the number will grow almost threefold, to 16 million.

That’s because the biggest risk factor for developing Alzheimer’s dementia is old age, and America is rapidly aging. According to Emanuel, 1 in 9 Americans older than 65 has the disease; 1 in 3 older than 85 has it. This insidious thief not only robs people of selfhood, but takes as much as $200 billion a year from the health-care budget, not counting all the unpaid care families provide.

That this terrifying finger of fate can point to anyone has spawned a host of supposed diagnoses and treatments not based on science, but on fear. Desperate people go to desperate measures to escape what, for many, is inevitable. (See our blog, “Online Alzheimer’s Tests Are a Waste of Time and Electrons.”

“[I]t’s only natural,” Emanuel writes, “that, in recent years, people have trumpeted the development of a new test that can measure the presence of beta-amyloid – the protein clumps in the brain that are one of the hallmarks of Alzheimer’s dementia. The patient is injected with a radioactive molecule that zeros in on beta-amyloid, and a positron emission tomography, or PET, scanner then detects the radioactivity.”

Last year, the FDA approved Eli Lilly’s radioactive molecule for patients who are being evaluated for Alzheimer’s disease and other causes of cognitive decline that result in forgetfulness or disorientation. A couple of months ago, Medicare said it would pay for the test for patients who are part of a randomized, controlled trial, which is the only way to definitively determine the value of the scan. The test costs from $3,000 to $5,000. Most private insurance doesn’t cover it.

Eli Lilly, of course, believes the cost of the test should be covered without restriction. The Alzheimer’s Association, an advocacy and patient support organization, agrees that the test should be more widely available.

Emanuel points out that the Alzheimer’s Association isn’t exactly objective: Since 2008, he says, it has received $1.6 million from Lilly. Last year, it got more than $4 million from all drug companies, many of which sell Alzheimer’s drugs.

Patients and their families, he says, should ask: What does the test really offer?

The only thing the scan can do, Emanuel says, is confirm that a patient’s cognitive problems are not caused by Alzheimer’s.

The scan does not affect symptoms or cure the disease. At best, it identifies what might be causing a patient’s forgetfulness. But – and here’s where the potential for real harm lies – it can get that diagnosis wrong.

“According to the company’s own post-mortem study of 59 terminally ill patients,” Emanuel writes, “false positives in scans for the presence of amyloid were reported in up to 3% of cases, while up to 20% of cases resulted in a false negative: Patients were diagnosed as not having amyloid and thus Alzheimer’s, even when they did.”

That’s 1 in 5 people who thought they were in the clear, and weren’t.

It’s not even that simple. Emanuel notes that although the scan is called an “Alzheimer’s test,” it doesn’t diagnose Alzheimer’s dementia – it only determines the presence of amyloid. “And our understanding of the connection between the two is shaky. While everyone who has Alzheimer’s also has amyloid, not everyone with amyloid has Alzheimer’s dementia.”

Nearly 1 in 3 cognitively normal elderly people, Emanuel says, has the protein clusters in their brains, which would appear on the scan. But they don’t have Alzheimer’s dementia, and there’s no way to know how likely they are to develop it in the future. “Imagine the anguish of that error,” Emanuel writes.

What if a scan could diagnose Alzheimer’s? It’s not likely to improve the outcome. There are five drugs on the market that treat dementia, and none is a cure. None can alter the disease’s progress to improve cognition. “At best,” Emanuel says, “they can relieve the symptoms of patients with moderate to severe Alzheimer’s for about six to 12 months. And let’s not forget these drugs all have side effects like fatigue, dizziness and pain.”

Even the people who advocate for wider, subsidized use of the test agree that it doesn’t help make decisions about whether or not to take medication; its primary benefit, said one advocate, isn’t therapy, but a little more time for planning.

Emanuel says that, given our aging population and our longer lifespans, we all should be planning for the possibility of Alzheimer’s; we should invest in long-term care insurance, exercise and stay socially active. Those are proven contributors to better health for longer duration.

Fear shouldn’t motivate society to waste a lot of money on a test that isn’t therapeutic. It should motivate society to spend more money on Alzheimer’s research, including trials like the one Medicare supports to evaluate the effectiveness of the test. “This research will take time,” Emanuel concludes, “but there is no other path forward.”

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