Historically, confirming Alzheimer’s disease required an autopsy to identify amyloid plaques, or a complex diagnostic process involving subjective reports, cognitive exams, spinal fluid analysis, and brain imaging. Today, four blood tests have received U.S. Food and Drug Administration (FDA) clearance, offering a less invasive and more accessible method to detect the earliest signs of the neurodegenerative condition.
Dr. Eric Reiman, CEO emeritus and lead researcher at the Banner Alzheimer’s Institute in Phoenix, described the development as a pivotal moment for the field. He noted that these tools allow for personalized care similar to oncology, enabling clinicians to inform diagnosis, prognosis, and staging with greater precision.
The landscape of available testing expanded significantly in August when two new assays were cleared. These additions aim to improve diagnostic accuracy and availability, particularly for younger populations. However, medical experts emphasize that these tests are not intended for universal screening.
The First Two Approved Tests
The initial FDA-cleared test, developed by Fujirebio and approved in May 2025, measures the ratio of beta-amyloid to tau proteins. This ratio indicates whether amyloid plaques are accumulating in the brain. Due to its requirement for specialized equipment, the test is not widely accessible through commercial laboratories.
Roche’s test, cleared in October 2025, detects a specific form of tau that correlates with amyloid buildup. It holds the distinction of being the first Alzheimer’s blood test that primary care physicians can prescribe to help rule out the disease.
Newer Options Expand Accessibility and Age Range
Two additional tests cleared in August are designed to streamline diagnosis. PrecivityAD2, created by diagnostics company C2N, utilizes mass spectrometry—a more sophisticated detection method than traditional assays—to provide a probability score regarding the likelihood of amyloid plaques. Unlike its predecessor, which was limited to certified labs, PrecivityAD2 can be performed by major laboratories and specific health systems, making it more widely available.
Crucially, PrecivityAD2 is the first test cleared for use in individuals as young as 40 who exhibit cognitive signs. This contrasts with other approved tests, which are generally reserved for patients in their mid-50s or older. Dr. Joel Braunstein, cofounder and CEO of C2N, highlighted the opportunity for early diagnosis and subsequent management planning.
The second new test, the Elecsys ptau217 plasma test from Roche, specifically targets ptau217, a modified tau protein that appears as amyloid begins to accumulate. Dr. Thomas Wisniewski, director of the Alzheimer’s Disease Research Center at NYU Langone Health, called it the most useful option currently available, citing its high sensitivity and specificity.
Guidelines for Use: Symptoms Over Screening
Medical consensus dictates that these tests should be reserved for individuals exhibiting signs of cognitive decline or memory issues, rather than serving as screening tools for healthy, asymptomatic people. Dr. Lawren VandeVrede, an assistant professor of neurology at the University of California San Francisco, expressed concern about inappropriate use in patients without symptoms.
She explained that a proper diagnostic workup must first evaluate medications, mood disorders, and other potential contributors to cognitive changes. While blood tests can increase diagnostic accuracy beyond the historical 85% threshold, Dr. Wisniewski cautioned that they indicate risk rather than providing definitive answers.
Future Potential for Asymptomatic Detection
The restriction on using these tests for risk assessment in healthy individuals stems from a lack of data on false-positive and false-negative rates in low-risk populations. However, this may shift within the next year as two major studies conclude. These trials are investigating whether existing Alzheimer’s drugs, lecanemab and donanemab, can reduce abnormal protein buildup and slow disease progression in people without memory problems.
If these studies succeed, blood tests could become essential for identifying early-stage disease before symptoms appear. Dr. Jason Hinman of UCLA noted that research suggests approximately one-third of cognitively intact older adults may show positive biomarkers. Such findings could pave the way for earlier treatment and using blood tests to monitor drug efficacy.
The Role of Primary Care and Interpretation
The availability of these tests empowers primary care physicians, who are often the first point of contact for cognitive concerns. Recent studies indicate that non-specialists can effectively interpret and manage diagnoses using blood results, using them to triage patients who may need further confirmatory testing like PET scans or spinal taps.
To guide this process, the Alzheimer’s Association has issued guidelines recommending that doctors first establish the presence of cognitive symptoms and rule out other causes such as depression, vitamin deficiencies, and sleep disorders before ordering a test. Maria Carrillo, chief science officer at the Alzheimer’s Association, stressed that significant preparatory work is necessary before patients should undergo blood testing for Alzheimer’s.
Interesting that ptau217 is considered the gold standard now. The field is moving fast.
I wish they had these tests when my mom was diagnosed. Years could have been saved.
What is the cost coverage like? My father needs this but insurance is a worry.
Why are they still restricting it to symptomatic patients? We need wider access now.
This is huge news. Early detection changes everything for treatment planning.