Doubts abound about a new Alzheimer’s blood test

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For the first time, people concerned about their risk of Alzheimer’s disease can go online, order a blood test and get the results in the privacy of their home.

This may seem interesting on the surface, but this development has Alzheimer’s researchers and clinicians up in arms.

Quest Diagnostics’ blood test, AD-Detect, measures elevated levels of amyloid-beta protein, a signature feature of Alzheimer’s. Introduced in late July, the test is primarily aimed at people age 50 and older who may have impaired memory and thinking and those with a family history of Alzheimer’s or a genetic risk for the condition.

Alzheimer’s is the scariest of all medical conditions, including cancer, and could be a huge market. About 7 million older adults in the United States have Alzheimer’s, and that number is expected to double by 2060 if advances in treatment do not occur.

But Alzheimer’s researchers and clinicians aren’t convinced that the Quest test is backed by sound scientific research. False-positive results are more likely, as is the likelihood that older adults will not understand the significance of their results, they say. The test should only be taken under the supervision of a physician, if they advise it. And, with an original price of $399 (recently discounted to $299) and not covered by insurance, it’s not cheap.

Although blood tests for Alzheimer’s may become common in the coming years, the Alzheimer’s Association says it is too early to offer such a test directly to consumers.

For its part, Quest, which also sells direct consumer-to-consumer tests for sexually transmitted diseases and a variety of other conditions, suggests that older adults can be trusted to respond responsibly to AD-Detect results. The test is not for diagnosing Alzheimer’s disease, the company emphasized; Instead, it is meant to help assess a person’s risk of developing the condition. But under a new, proposed biological definition of Alzheimer’s, excess amyloid could automatically trigger a diagnosis of “preclinical” Alzheimer’s disease.

Michael Racke, Quest’s medical director of neurology, said those who test positive may be motivated to talk to their doctors about cognitive symptoms and seek a comprehensive evaluation from dementia specialists. Others may simply want to adopt behaviors related to brain health, such as getting more exercise and maintaining healthy blood pressure, blood sugar, and cholesterol levels.

“People who do consumer-initiated testing are often very motivated to figure out what they can do to help reduce the risk of disease,” he said.

To get the test, a person must first visit the AD-Detect test website and report that they are experiencing mild cognitive decline and have at least one other risk factor. (These types of self-reported complaints are often unreliable, experts note.) The order then goes automatically to a doctor provided by Quest, who will order a blood test at a Quest laboratory.

The results of classifying an individual as low, moderate or high risk will be provided in a secure patient portal. Post-test counseling is not mandatory, but individuals can speak with a physician who pays Quest if they wish. (There is a separate $13 “Physician Service Fee”.)

A new poll from the University of Michigan confirms that older adults will take the results seriously: 97 percent of seniors said they would take steps to improve brain health after receiving a positive result from a blood test, while 77% said they would consider making changes financially or End of life plan.

But research scientists and clinicians are concerned that Quest has not published any peer-reviewed studies documenting the test’s validity. The company’s preliminary data, presented at the 2022 Alzheimer’s Association International Conference in San Diego, suggests that there is a relatively high chance of false-positive results, said Suzanne Schindler, associate professor of neurology at Washington University School of Medicine. Louie.

That’s a significant problem because telling someone the biological changes associated with Alzheimer’s disease is “a big deal and you want to be as accurate as possible,” Schindler noted.

At least three scientific studies providing more details about the AD-Detect test have been submitted to medical journals and could be published by the end of this year, Racke said.

Experts also question the usefulness of the test since a positive result (indicating abnormal levels of amyloid in the blood) does not necessarily mean that a person has Alzheimer’s disease. Amyloid accumulates in the brain slowly over decades, usually beginning in middle age and becoming more common as people age.

“This test gives you a vague answer. We don’t know if you’ll develop dementia, or when symptoms might start, or, really, what the risk is for a person,” said Mira Sheffrin, medical director of Stanford Health Care’s Senior Care Clinic.

Also, the cognitive symptoms that prompt someone to get tested can be caused by a variety of factors, including mini-strokes, sleep apnea, thyroid problems, vitamin B12 deficiency, or drug interactions. If an older adult becomes anxious, depressed or depressed after learning they are at risk for Alzheimer’s — another source of anxiety — “they may not go for further evaluation and get appropriate care,” says Rebecca Edelmayer, senior director of scientific engagement at the Alzheimer’s Association.

A University of Michigan poll confirms the potential for misunderstandings. After receiving a positive blood test result, 74% of seniors said they would believe they were likely to develop Alzheimer’s, and 64% said they would experience significant distress.

Because the science behind the blood test for Alzheimer’s is still developing and because “patients may not understand the uncertainty of test results,” Edelmayer said, the Alzheimer’s Association “does not endorse the use of the AD-Detect test by consumers.”

Quest’s blood test is one of several developments changing the landscape of Alzheimer’s care in the United States. In early July, the FDA granted full approval to Lakembi, an anti-amyloid therapy that slightly slows cognitive decline in people with mild cognitive impairment and early-stage Alzheimer’s. Early detection of cognitive symptoms and diagnosis of cognitive dysfunction has become even more important now that this disease-modifying drug is available.

Also in July, a work group convened by the National Institute on Aging and the Alzheimer’s Association proposed a new definition of Alzheimer’s disease for use in clinical practice.

Previously, Alzheimer’s disease was diagnosed when there was underlying brain pathology (amyloid plaques and tau tangles) as well as cognitive symptoms (memory loss, poor decision-making, confusion, among others) and accompanying impairments (difficulties managing money, wandering,) problems with self-care, and more). According to a draft of the work group’s report, under the new definition, Alzheimer’s would be defined entirely on a biological basis, “a continuum that first becomes apparent with the presence of pathological changes in the brain”.

This means that “you can get a positive result from the QUEST test and if these guidelines are followed, you can be diagnosed with Alzheimer’s disease, even if you are cognitively normal,” warns Eric Wiedera, a professor of medicine at the University of California-Sun. Francisco.

Demand for follow-up evaluations by dementia specialists may be high and contribute to already long waits for care, he suggests.

Additional concerns about testing relate to protecting privacy and the potential for discrimination. No federal law protects people who get Alzheimer’s biomarker results from discriminatory practices, such as employment discrimination or the denial of life, disability, or long-term care insurance. (The Genetic Information Nondiscrimination Act applies only to genetic testing.) And “laws protecting the privacy of health information don’t apply here,” says Emily Largent, assistant professor of medical ethics and health policy at the University of Pennsylvania. Perelman School of Medicine.

Notably, HIPAA, the Health Insurance Portability and Accountability Act, does not extend to laboratory tests marketed directly to consumers.

The bottom line: Before taking a test, “older adults need to ask themselves, ‘Why do I want to know this? What do I do with the information? How do I respond? What will I change in the future?'” says C. Monroe Cullum, a neuropsychologist and distinguished professor of clinical psychology at the University of Texas Southwestern Medical Center. “This test needs to be used very cautiously and with great forethought.”

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Kaiser Health NewsReprinted from this article khn.orgA national newsroom that produces in-depth journalism about health issues and is one of KFF’s core operating programs – the independent source for health policy research, polling and journalism.



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