New Clinical Guidelines Recommend Use of Blood Tests Instead of Brain Scans for Alzheimer’s Diagnosis

Alzheimer’s disease is a progressive neurodegenerative condition that remains challenging to diagnose early and accurately, particularly in individuals with cognitive impairment. Despite the availability of tools such as PET imaging and cerebrospinal fluid (CSF) testing, these methods are often costly, less accessible, and not always acceptable to patients.

Many blood-based biomarker (BBM) tests have been introduced to the market, but there is significant variability in their diagnostic accuracy, and patients and clinicians may mistakenly assume these tests are interchangeable. In response to the need for clearer guidance on the responsible use of BBM tests, a new clinical practice guideline (CPG) now aims to help healthcare professionals improve diagnostic precision and reduce misuse of these emerging tools.

The Alzheimer’s Association (Chicago, IL, USA) has released the first in a series of CPGs for the diagnosis, treatment, and care of Alzheimer’s and all other dementia. The guideline focuses on the use of blood-based biomarker tests for patients with objective cognitive impairment being seen in specialized memory care settings. The recommendations are linked to a systematic review using a robust and transparent methodology, and will be updated regularly as evidence evolves.

A panel of 11 clinicians—including neurologists, geriatricians, nurse practitioners, physician assistants, and subject-matter experts—conducted a systematic review of 49 observational studies, evaluating 31 BBM tests that measure biomarkers such as plasma phosphorylated tau (p-tau) and amyloid-beta (Aβ). The tests examined included analytes like p-tau217, %p-tau217, p-tau181, p-tau231, and Aβ42/Aβ40 ratios. Using the GRADE (Grading of Recommendations Assessment, Development and Evaluation) methodology, the panel formulated brand-agnostic, performance-based recommendations.

The guideline outlines two key uses: as a triaging tool when sensitivity is ≥90% and specificity is ≥75%, and as a confirmatory tool when both sensitivity and specificity are ≥90%. It also includes a Good Practice Statement advising that BBM tests be ordered only after comprehensive clinical evaluation and interpreted within the context of each patient’s care. The guideline, published in Alzheimer’s & Dementia: The Journal of the Alzheimer’s Association, underscores that BBM tests, while promising, should not replace clinical judgment or full diagnostic evaluation.

By offering a structured and transparent evidence-based framework, the guideline empowers clinicians to make informed decisions on the appropriate use of BBM tests and ultimately improve outcomes for patients and families affected by Alzheimer’s. The Alzheimer’s Association plans to release additional clinical practice guidelines through its ALZPro initiative, covering topics such as cognitive assessment tools, staging criteria, treatment implementation, and dementia prevention in the coming years.

“Not all BBM tests have been validated to the same standard or tested broadly across patient populations and clinical settings, yet patients and clinicians may assume these tests are interchangeable,” said Rebecca M. Edelmayer, Ph.D., Alzheimer’s Association vice president of scientific engagement and a co-author of the guideline. “This guideline helps clinicians apply these tools responsibly, avoid overuse or inappropriate use, and ensure that patients have access to the latest scientific advancements.”

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Alzheimer's Association