Quest Diagnostics (NYSE: DGX), a leader in diagnostic innovation, has launched a new blood test designed to help physicians confirm amyloid brain pathology in patients with mild cognitive impairment (MCI) or dementia—a critical step in diagnosing Alzheimer’s disease (AD). The AD-Detect™ Aβ42/40 and p-tau217 Evaluation test offers a less invasive, more accessible alternative to traditional diagnostic methods like PET scans and spinal taps.
A Breakthrough in Alzheimer’s Diagnostics
The new test combines two key biomarkers:
- Amyloid beta (Aβ42/40) ratio, measured using Quest’s proprietary mass spectrometry technology.
- Phosphorylated tau (p-tau217), detected via an advanced immunoassay.
These biomarkers are analyzed using a proprietary algorithm to generate an AD-Detect Likelihood Score™, which estimates the probability of amyloid pathology due to Alzheimer’s. The test builds on Quest’s existing AD-Detect portfolio, which previously assessed Aβ42/40, p-tau217, p-tau181, and ApoE (a genetic risk marker) individually.
High Accuracy Backed by Research
Data presented at the American Academy of Neurology (AAN) Annual Meeting this week demonstrated the test’s strong performance:
- 89% positive predictive value (PPV) – indicating a high likelihood of Alzheimer’s when the test is positive.
- 89% negative predictive value (NPV) – suggesting a low likelihood of disease when negative.
- 91% sensitivity and specificity, with further improvements when ApoE genetic data is included.
In a real-world analysis of 4,326 patient specimens, the test categorized:
- 42% as high likelihood for amyloid PET positivity.
- 51% as low likelihood.
- 7% as indeterminate, a figure that dropped to 10% with ApoE inclusion.
“This test meets the CEOi’s performance criteria and provides physicians with a reliable, scalable tool to accelerate diagnosis,” said Dr. Michael Racke, Quest’s Medical Director of Neurology and study co-author. “It could reduce reliance on costly PET scans and invasive lumbar punctures.”
Expanding Access to Alzheimer’s Testing
With nearly 7 million Americans1 living with Alzheimer’s—a number expected to double by 2060—early and accurate diagnosis is crucial. The new test is now available nationwide (except New York) through Quest’s network of 8,000 patient access points, including labs and mobile phlebotomy services.
“Our goal is to make advanced diagnostics more affordable and accessible,” said Kathleen Valentine, VP and General Manager of Neurology at Quest. “Blood-based testing can transform Alzheimer’s into a manageable condition by enabling earlier intervention.”
The Future of Alzheimer’s Care
As new therapies emerge, Quest’s AD-Detect suite positions blood testing as a first-line diagnostic tool, potentially reshaping Alzheimer’s care. The company continues to invest in research, with studies published in Alzheimer’s & Dementia2, Frontiers in Neurology3, and the Journal of Investigative Medicine4.
About Quest Diagnostics
Quest Diagnostics empowers healthier lives through diagnostic insights, serving 1 in 3 U.S. adults annually. With nearly 55,000 employees, Quest leverages the world’s largest clinical lab database to drive innovation in brain health and chronic disease management.
- About Alzheimer’s – CDC – (Accessed on Apr 11, 2025) ↩︎
- Diffusion MRI relates to plasma Aβ42/40 in PET negative participants without dementia – Alzheimer’s Association – Wiley Online Library – (Accessed on Apr 11, 2025) ↩︎
- Study in Frontiers in Neurology Affirms Amyloid Blood Test Can Help Identify Patients Who May Forgo Imaging Evaluation for Alzheimer’s Disease – Quest Diagnostics – (Accessed on Apr 11, 2025) ↩︎
- New plasma LC-MS/MS assays for the quantitation of beta-amyloid peptides and identification of apolipoprotein E proteoforms for Alzheimer’s disease risk assessment – Sage Journals – (Accessed on Apr 11, 2025) ↩︎
References
- Quest Diagnostics Unveils Groundbreaking Blood Test to Improve Alzheimer’s Disease Diagnosis – PR News Wire – (Accessed on Apr 10,2025)
- Quest Diagnostics Launches New AD-Detect™ Blood Test to Aid in Confirming Alzheimer’s Disease – Quest Diagnostics – Accessed on Apr 10,2025)
