A new clinical guideline released by the Alzheimer’s Association has introduced a system for clinicians to choose blood-based biomarkers (BBMs) to aid in the diagnosis of Alzheimer’s disease (AD). The evidence-based guidelines recommend using BBMs with ≥ 90% sensitivity and specificity as a substitute for amyloid PET or cerebrospinal fluid (CSF) biomarker testing. Tests with ≥ 90% sensitivity but only ≥ 75% specificity can be used as triaging tests, where a positive result should be confirmed with CSF or PET testing.
The guideline aims to standardize the use of BBMs in clinical practice and meets the growing need for rapid and accurate AD diagnosis. With the approval of anti-amyloid beta therapies, clinicians require more precise diagnostic tools. The new guidelines focus on individuals with mild cognitive impairment or dementia undergoing assessment by providers trained in memory disorders.
The panel of experts conducted a systematic review of 1050 papers to assess the accuracy of BBMs detecting amyloid pathology for triaging and confirmatory tests. The recommended biomarkers include plasma phosphorylated-tau (p-tau) and Aβ tests measuring specific analytes.
While the guideline does not endorse specific tests, it highlights the importance of choosing the right test for the right patient at the right time. Researchers acknowledge that false positive or false negative results can delay accurate diagnosis and treatment. The expert panel is already working on next steps, including determining if these biomarkers can be used as confirmatory or triage tests in cognitively unimpaired people and in primary care settings.
David Knopman, a clinical neurologist, emphasized that the use of any AD-specific biomarker depends on context, including history, cognitive assessment, and presence of non-AD features. While the guideline is reasonable for separate functions of triaging and confirming AD biology, it carries risks of misuse.
Source: https://www.medscape.com/viewarticle/first-guideline-alzheimers-blood-based-biomarker-tests-2025a1000kcf