For the first time, people worried about their risk of Alzheimer鈥檚 disease can go online, order a blood test, and receive results in the privacy of their homes.
This might seem appealing on the surface, but the development has Alzheimer鈥檚 researchers and clinicians up in arms.
The Quest Diagnostics blood test, AD-Detect, measures elevated levels of amyloid-beta proteins, a signature characteristic of Alzheimer鈥檚. Introduced in late July, the test is targeted primarily at people 50 and older who suspect their memory and thinking might be impaired and people with a family history of Alzheimer鈥檚 or genetic risks for the condition.
Given Alzheimer鈥檚 is among the most feared of all medical conditions, along with cancer, this could be a sizable market, indeed. Nearly 7 million older adults in the U.S. have Alzheimer鈥檚, and that number is expected to double by 2060 if medical breakthroughs don鈥檛 occur.
But Alzheimer鈥檚 researchers and clinicians aren鈥檛 convinced the Quest test is backed by sound scientific research. The possibility of false-positive results is high, as is the likelihood that older adults won鈥檛 understand the significance of their results, they say. The test should be taken only under a physician鈥檚 supervision, if at all, they advise. And, priced originally at $399 (recently discounted to $299) and not covered by insurance, it isn鈥檛 cheap.
Though blood tests for Alzheimer鈥檚 are likely to become common in the years ahead, the Alzheimer鈥檚 Association said it鈥檚 premature to offer a test of this kind directly to consumers.
For its part, Quest, which also sells direct-to-consumer tests for sexually transmitted diseases and various other conditions, suggests older adults can be trusted to respond responsibly to AD-Detect results. The test is not meant to diagnose Alzheimer鈥檚, the company stressed; instead, it鈥檚 meant to help assess an individual鈥檚 risk of developing the condition. But under a new, proposed biological definition of Alzheimer鈥檚, excess amyloid could automatically trigger a diagnosis of 鈥減reclinical鈥 Alzheimer鈥檚.
Michael Racke, Quest鈥檚 medical director of neurology, said individuals who test positive might be inspired to talk to their physicians about cognitive symptoms and seek comprehensive evaluations from dementia specialists. Others may just want to adopt behaviors associated with brain health, such as exercising more and maintaining healthy blood pressure, blood sugar, and cholesterol levels.
鈥淧eople who do consumer-initiated testing are often very motivated to figure out what they can do to help reduce the risk of disease,鈥 he said.
To get the test, a person first needs to go to the and report that they鈥檙e experiencing mild cognitive decline and have at least one other risk factor. (Self-reported complaints of this kind are often unreliable, experts note.) The order then goes automatically to a doctor paid by Quest, who will order a blood test to be drawn at a Quest laboratory.
Results classifying a person as low, medium, or high risk will be provided on a secure patient portal. Post-test counseling isn鈥檛 mandatory, but individuals can speak to a physician paid by Quest, if they like. (There is a separate $13 鈥減hysician service fee.鈥)
A confirms that older adults will take results seriously: Ninety-seven percent of seniors said they would take steps to improve brain health upon receiving a positive result from a blood test, while 77% said they would consider changes to financial or end-of-life plans.
But research scientists and clinicians worry that Quest hasn鈥檛 published any peer-reviewed studies documenting the test鈥檚 validity. The company鈥檚 preliminary data released at the 2022 Alzheimer鈥檚 Association International Conference in San Diego suggests there鈥檚 a relatively high chance of false-positive results, said Suzanne Schindler, an associate professor of neurology at Washington University School of Medicine in St. Louis.
That鈥檚 a significant problem because telling someone they have biological changes associated with Alzheimer鈥檚 disease is a 鈥渂ig deal and you want to be as accurate as possible,鈥 Schindler noted.
Racke said at least three scientific studies giving more details about the AD-Detect test have been submitted to medical journals and might be published by the end of this year.
Experts also question the usefulness of the test since a positive result (indicating abnormal levels of amyloid in the blood) doesn鈥檛 mean an individual will definitely develop Alzheimer鈥檚 disease. Amyloid in the brain accumulates slowly over the course of decades, typically beginning in middle age, and becomes more common as people age.
鈥淭his test gives you a fuzzy answer. We don鈥檛 know whether you鈥檙e going to get dementia, or when symptoms might begin, or, really, how high the risk is for any individual,鈥 said Meera Sheffrin, medical director of the Senior Care clinic at Stanford Healthcare.
Also, cognitive symptoms that prompt someone to take the test might be due to a wide variety of other causes, including mini-strokes, sleep apnea, thyroid problems, vitamin B12 deficiency, or medication interactions. If an older adult becomes anxious, depressed, or hopeless upon learning they鈥檙e at risk for Alzheimer鈥檚 鈥 another source of concern 鈥 鈥渢hey may not go for further evaluation and seek appropriate care,鈥 said Rebecca Edelmayer, senior director of scientific engagement at the Alzheimer鈥檚 Association.
The University of Michigan poll confirms the potential for misunderstanding. Upon receiving a positive result from a blood test, 74% of seniors said they would believe they were likely to develop Alzheimer鈥檚 and 64% said they would be likely to experience significant distress.
Because the science behind blood tests for Alzheimer鈥檚 is still developing and because 鈥減atients may not really understand the uncertainty of test results,鈥 Edelmayer said, the Alzheimer鈥檚 Association 鈥渄oes not endorse the use of the AD-Detect test by consumers.鈥
Quest鈥檚 blood test is one of several developments altering the landscape of Alzheimer鈥檚 care in the United States. In early July, the FDA granted full approval to Leqembi, an anti-amyloid therapy that slightly slows cognitive decline in people with mild cognitive impairment and early-stage Alzheimer鈥檚. Early detection of cognitive symptoms and diagnosis of cognitive dysfunction have assumed greater importance now that this disease-modifying drug is available.
Also in July, a work group convened by the National Institute on Aging and the Alzheimer鈥檚 Association of Alzheimer鈥檚 disease to be used in clinical practice.
Previously, Alzheimer鈥檚 could be diagnosed only when there was evidence of underlying brain pathology (amyloid plaques and tau tangles) as well as cognitive symptoms (memory loss, poor judgment, disorientation, among others) and accompanying impairments (difficulty with managing finances, wandering, problems with self-care, and more). Under the new definition, Alzheimer鈥檚 would be defined purely on a biological basis, as a 鈥渃ontinuum that is first evident with the appearance of brain pathologic changes鈥 including amyloid accumulation, according to a draft of the work group鈥檚 report.
That would mean 鈥測ou can get a positive result from the Quest test and be diagnosed with Alzheimer鈥檚 disease if these guidelines are adopted, even if you鈥檙e cognitively normal,鈥 cautioned Eric Widera, a professor of medicine at the University of California-San Francisco.
Demand for follow-up evaluations by dementia specialists is likely to be high and contribute to already-long waits for care, he suggested.
Additional concerns about the test relate to safeguarding privacy and the potential for discrimination. No federal laws protect people who receive Alzheimer鈥檚 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 tests.) And 鈥渓aws that normally protect the privacy of health information do not apply in this space,鈥 said Emily Largent, an assistant professor of medical ethics and health policy at the University of Pennsylvania鈥檚 Perelman School of Medicine.
Notably, HIPAA, the Health Insurance Portability and Accountability Act, doesn鈥檛 extend to laboratory tests marketed directly to consumers.
The bottom line: Before taking a test, 鈥渙lder adults need to ask themselves, 鈥榃hy do I want to know this? What will I do with the information? How will I react? What would I change in the future?鈥欌 said C. Munro Cullum, a neuropsychologist and distinguished professor of clinical psychology at the University of Texas Southwestern Medical Center. 鈥淭his test needs to be used very cautiously and with great forethought.鈥
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