Quest Diagnostics, a company that makes different tests for various health conditions, is now marketing a new test called AD-Detect that claims to assess the ratio of two peptides of amyloid beta, a hallmark of Alzheimer's disease. People can now order this test, currently priced at $299, without seeing a doctor. Quest also offers post-testing consultations with a Quest physician for an additional fee. There are concerns about this test, however, because there is no published data about whether the test has been validated in any way. The test also only measures levels of amyloid in the blood, and can indicate whether they are unusual, which is not necessarily a positive diagnosis for Alzheimer's disease.
Suzanne Schindler, an associate professor of neurology at Washington University School of Medicine in St. Louis, noted that there is a relatively high likelihood of false-positive results, according to information presented by the company at the 2022 Alzheimer's Association International Conference in San Diego.
However, the medical director of neurology at Quest, Michael Racke, has said that three studies about the AD-Detect test have been submitted to medical journals and could be published soon.
Right now, there is also concern about how consumers can use the information they might get from this test. Currently, abnormal levels of amyloid in the blood are not considered to be a diagnosis for Alzheimer's or an indicator that the disease is imminent. A buildup of amyloid also tends to occur as people age, and not just because they are getting a neurodegenerative disease.
The symptoms of dementia could also be caused by many different things, and not necessarily Alzheimer's.
Diagnostic tests like this one can be nuanced, and are best used with the guidance of health practitioners. But this test may not be used this way.
This test is also being introduced at a time when diagnostic standards for Alzheimer's may be changing. It was typical to evaluate patients for cognitive impairments, and pathology in the brain such as tau tangles and amyloid plaques, when considering an Alzheimer's diagnosis. But it was recently proposed that brain pathology alone could be sufficient for a diagnosis. In that case, a person who is cognitively normal might be diagnosed with Alzheimer's from this test, noted Eric Widera, a professor of medicine at the University of California-San Francisco. It can take a long time for people to get an appointment for follow-up neurological evaluations too, so people who use this test may not be able to get the answers they seek quickly.
Experts urge people to use caution before ordering this test, and to consider what they'll do with the information if they receive it.
Sources: Medical Express, Quest Diagnostics