Alzheimer's Blood Tests Draw Patient Enthusiasm and Clinician Caution
Alzheimer's blood tests are gaining FDA clearances and strong patient interest, yet surveys show clinicians remain skeptical about their reliability and clinical benefit. A UK survey found fewer than one-third of psychiatrists have used biomarkers, while only 6% of memory services meet access guidelines. An ethical framework urges careful implementation, especially in primary care.
Blood-based biomarker tests for Alzheimer's disease are generating strong public interest and regulatory momentum, but surveys of patients and clinicians reveal persistent questions about their reliability and clinical benefit. A survey published in the journal Alzheimer's & Dementia found that 85% of patients said they would take a blood test to assess their Alzheimer's risk if their doctor recommended it, while a UK survey found that fewer than one-third of old-age psychiatrists had used such biomarkers.
The U.S. Food and Drug Administration has cleared two blood tests for Alzheimer's disease in the past year, both for people 55 and older who are already showing symptoms. They do not diagnose Alzheimer's on their own and are used alongside other tests, such as a PET scan. The FDA noted that the main risk of the tests is inaccurate results, including false positives and false negatives, which could lead to an inappropriate diagnosis of, and unnecessary treatment for, Alzheimer's disease. According to a paper in Nature, the Elecsys pTau181 test has been FDA-cleared for use in primary-care settings, and in May 2025, the Lumipulse G p-tau217/β-amyloid 1-42 plasma ratio test became the first blood-based biomarker to receive FDA 510(k) clearance for clinical use in Alzheimer's diagnosis.
The survey, which included responses from nearly 600 adults with an average age of 62 at primary care clinics in the Chicago area, found that nearly 3 in 4 respondents said they would expect to feel distressed after a positive result, even as most said they would likely take steps to improve their brain health. About half of respondents reported having a family history of Alzheimer's disease, though none had been diagnosed, and most had never heard of the tests before taking the survey. A clinical and primary care psychologist at Northwestern University Feinberg School of Medicine, who does not order the tests, said there is still a lot to be ironed out and that the tests are 'not ready for prime time.'
A survey of UK old-age psychiatrists, conducted in November 2024 among 172 members of the Royal College of Psychiatrists Old Age Psychiatry Faculty, found that fewer than one-third had used biomarkers for Alzheimer's disease. The study identified 'Knowledge,' 'Environmental Context and Resources,' and 'Goals' as key barriers to use, while 'Behavioural Regulation,' 'Social Influences,' and 'Intention' were enablers. Regression analyses showed that 'Memory, Attention and Decision Processes,' 'Beliefs about Consequences,' and 'Social Influences' were positively associated with intention to use blood-based biomarkers, while 'Optimism' and 'Emotion' were negatively associated. Only 6% of UK memory services meet Alzheimer's disease biomarker access guidelines.
An ethical framework published in Nature proposes guidance for decision-making around blood-based biomarker testing in primary care, where patients often present with cognitive impairment and multiple chronic conditions. The framework addresses clinical benefit, patient values, risk, and justice, and considers medical futility as an ethical boundary for when testing is unlikely to offer meaningful benefit. It notes that plasma p-tau217, used alone or in combination with the Aβ42/40 ratio, has demonstrated strong diagnostic performance and high discriminative accuracy in differentiating Alzheimer's from other neurodegenerative conditions.
Despite current limitations, there are at least 25 commercially available blood tests worldwide, and more in development, according to the Alzheimer's Association. The tests are simple to administer, relatively inexpensive, and more convenient than PET scans or MRI, said the association's vice president of scientific engagement. However, there is no cure for Alzheimer's disease, which affects about 7 million people in the U.S., according to the Mayo Clinic. The two FDA-approved drugs — Leqembi and Kisunla — aim to slow, not cure, the disease, with mixed evidence for how well they work and potentially serious side effects including brain swelling and bleeding. Diet and exercise may help reduce risk, but their effects are limited.