Quest Diagnostics Launches New AD-Detect™ Blood Test to Aid in Confirming Alzheimer's Disease

Rhea-AI Summary

Quest Diagnostics (NYSE: DGX) has launched AD-Detect™, a new laboratory blood test designed to confirm amyloid brain pathology in Alzheimer's disease patients with mild cognitive impairment or dementia. The test combines blood levels of amyloid beta 42/40 and p-tau217 to produce the AD-Detect Likelihood Score™.

Research presented at the 2025 AAN Annual Meeting demonstrated the test's 91% sensitivity and specificity, with positive and negative predictive values of 89% in mild cognitive impairment populations. The test showed strong performance in real-world specimens, categorizing 42% as high likelihood, 51% as low likelihood, and 7% as indeterminate for PET positivity.

The test is now available nationwide (except New York) through Quest's network of approximately 8,000 patient access points. This blood-based test offers a more affordable and less invasive alternative to traditional amyloid PET imaging and cerebral spinal fluid testing.

Positive

• High accuracy with 91% sensitivity and specificity in detecting Alzheimer's
• Strong commercial potential with access to 8,000 patient service points nationwide
• More cost-effective solution compared to traditional testing methods
• Addresses large market with 7 million Americans having Alzheimer's

Negative

• Not available in New York state market
• 15% indeterminate risk rate in initial testing
• validation against non-AD causes of dementia

Insights

Healthcare Industry Analyst

Quest Diagnostics' launch of the AD-Detect™ blood test represents a significant market opportunity in the growing Alzheimer's diagnostics space. With $18.3 billion market cap, DGX is strategically positioning itself at the intersection of two powerful healthcare trends: the shift toward blood-based biomarkers and the expanding Alzheimer's treatment landscape.

The addressable market is substantial - nearly 7 million Americans have Alzheimer's, projected to double to 14 million by 2060. Additionally, 12-18% of adults over sixty have mild cognitive impairment, creating a massive screening opportunity. The test's 89% positive and negative predictive values in real-world populations significantly outperform most diagnostic tools.

Quest's extensive infrastructure (approximately 8,000 patient access points including 2,000 service centers) provides immediate nationwide scalability, allowing rapid commercialization and revenue capture. The centralized testing model at their specialized California laboratory creates operational efficiency.

This product launch is particularly well-timed with the emergence of new Alzheimer's therapies that require accurate diagnosis before treatment. By addressing the 94% of physicians seeking more cost-effective diagnostic alternatives to PET scans and lumbar punctures, Quest has created a compelling value proposition for both providers and payers.

Neurological Diagnostics Specialist

The AD-Detect™ test represents a significant advancement in Alzheimer's diagnostics by combining two critical biomarkers - amyloid beta (Aβ) 42/40 ratio and phosphorylated tau217 - into a composite score with remarkable accuracy. The 91% sensitivity and specificity are exceptional for a blood-based test, approaching the performance of far more invasive and expensive gold standards.

What's particularly impressive is the test's validation in a heterogeneous cohort with only 39.1% amyloid PET positivity, demonstrating robust performance in challenging real-world populations. The inclusion of ApoE genetic testing further enhances predictive values while reducing indeterminate results from 15% to 10%.

This test addresses several critical diagnostic bottlenecks. First, it democratizes access by eliminating dependence on specialists and advanced imaging facilities. Second, it provides actionable results that enable physicians to confidently rule in or rule out Alzheimer's pathology without necessarily requiring confirmatory PET or CSF testing. Third, it effectively stratifies patients with 42% showing high likelihood and 51% showing low likelihood of PET positivity.

The company's proprietary tandem mass spectrometry for Aβ measurement provides technical advantages over antibody-based approaches used by competitors. This test substantially accelerates the diagnostic pathway, potentially reducing delays in appropriate treatment initiation while limiting unnecessary exposure to powerful medications for those without Alzheimer's pathology.

In an oral presentation at the 2025 AAN Annual Meeting, Quest scientists presented data suggesting the test can accurately assess Alzheimer's disease pathology with greater than 90% sensitivity and specificity

SECAUCUS, N.J., April 9, 2025 /PRNewswire/ -- Quest Diagnostics (NYSE: DGX), a leader in diagnostic information services, including advanced diagnostics for brain health, today announced the launch of a new laboratory blood test designed to help physicians confirm amyloid brain pathology due to Alzheimer's disease (AD) in patients with mild cognitive impairment (MCI) or dementia.

The laboratory-developed test, named AD-Detect™ Abeta 42/40 and p-tau217 Evaluation, combines results of blood levels of amyloid beta (AB) 42/40 determined by the company's proprietary tandem mass spectrometry techniques with blood levels of p-tau217 determined by an in vitro immunoassay test. The test results are then used to produce the AD-Detect Likelihood Score™, a composite interpretation created through a proprietary algorithm validated utilizing a well-characterized cohort from the 1Florida Alzheimer's Disease Research Center (ADRC).

The new Quest test panel builds on prior AD-Detect tests that individually assess AB 42/40 and p-tau217, as well as p-tau181 and the ApoE isoform, a genetic risk marker. Those tests help providers assess risk of AD rather than confirm likelihood of amyloid brain pathology due to AD.

"Quest's AD-Detect suite of advanced diagnostics has grown to include a range of validated blood-based biomarkers, giving providers options for personalizing testing for the individual patient," said Kathleen Valentine, Vice President and General Manager, Neurology, Quest Diagnostics. "Quest's innovations in blood testing combined with our broad patient access are making it easier, faster and more affordable to evaluate patients for AD and other complex diseases."

Research demonstrates test's strong alignment with PET
In AD, a protein called amyloid forms plaques in the brain, triggering changes in another protein, tau, and causing it to twist into tangles. These plaques and tangles disrupt brain cell function while also causing abnormal levels of both proteins to circulate in the blood stream.

In an oral presentation given this week at the American Academy of Neurology (AAN)'s Annual Meeting in San Diego, Quest researchers presented data demonstrating that the new test would have a positive predictive value (PPV, the likelihood of disease) of 89% and negative predictive value (NPV, the likelihood there is no disease) of 89% in a population with mild cognitive impairment when the test cut offs were set at 91% sensitivity and 91% specificity. The addition of ApoE, a genetic risk marker, further improved the predictive values. The percentage of patients with likelihood of indeterminate risk was 15%, which decreased to 10% when ApoE test results were included. Importantly, the population was heterogenous and had a low prevalence of beta amyloid PET positivity (39.1% for all patients and 46% for those with MCI or AD), suggesting the test's reliability in a real-world population that includes individuals who do not have AD.

The researchers also categorized 4,326 "real-world specimens" tested by Quest for AB 42/40, p-tau217 and ApoE4 values. The model and cut points categorized these specimens as having 42% high likelihood, 51% low likelihood, and 7% indeterminant likelihood for PET positivity.

"As the population ages and new therapies emerge, our new AD-Detect test will help fill the need for scalable, high-volume solutions that broaden access to robust and affordable evaluation of AD," said study co-author Michael Racke, MD, a board-certified neurologist and Medical Director of Neurology at Quest Diagnostics. "Our new test fulfills acceptable performance criteria set forth by the CEOi. We believe it will give providers greater confidence to move patients with a high likelihood score for AD more quickly on the path to treatment and potentially prevent the use of PET and lumbar puncture in patients whose blood values strongly indicate they do not have AD."

While amyloid PET imaging and cerebral spinal fluid testing are established methods for aiding the diagnosis of AD, they are significantly more expensive, invasive and specialist-dependent than blood-based tests.

The study's strengths included significant ethnic diversity in the population (over 50% Hispanic) while limitations included using a predictive model that did not evaluate performance of the biomarkers in the context of non-AD causes of dementia. The study adds to a growing body of research on the Quest AD-Detect test portfolio, including studies published in the Journal of Investigative Medicine, Frontiers in Neurology and Alzheimer's & Dementia.

Broadening access to quality AD assessment 
With the exception of New York, physicians in the United States may now order the test.¹ Patients with a physician's order can provide a blood draw for testing through Quest's network of patient sites. Quest maintains approximately 8,000 patient access points, including an extensive patient service center network of approximately 2,000 locations in the U.S., as well as phlebotomists in physician offices and mobile phlebotomy services. Specimens will be transported for testing to Quest's state-of-the-art laboratory in San Juan Capistrano, California.

Nearly 7 million Americans have Alzheimer's, the most prevalent dementia, a number projected to reach 14 million by 2060. Approximately 12-18% of adults over the age of sixty are living with mild cognitive impairment, a potential sign of AD. Seventy-seven percent of physicians say new therapies will transform Alzheimer's into a chronic, manageable disease, and 94% of physicians say blood tests would be more cost effective for the healthcare system compared to more invasive methods of detection (e.g., lumbar puncture, imaging studies) according to a special report from Quest.

Quest is committed to developing innovative advanced diagnostics to aid in evaluating AD and other brain diseases. For more information, visit www.QuestForTheCure.com.

About Quest Diagnostics
Quest Diagnostics works across the healthcare ecosystem to create a healthier world, one life at a time. We provide diagnostic insights from the results of our laboratory testing to empower people, physicians and organizations to take action to improve health outcomes. Derived from one of the world's largest databases of de-identifiable clinical lab results, Quest's diagnostic insights reveal new avenues to identify and treat disease, inspire healthy behaviors and improve healthcare management. Quest Diagnostics annually serves one in three adult Americans and half the physicians and hospitals in the United States, and our nearly 55,000 employees understand that, in the right hands and with the right context, our diagnostic insights can inspire actions that transform lives and create a healthier world. www.QuestDiagnostics.com.

¹ Except in New York state, where the company plans to apply for approval to offer the test clinically.

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SOURCE Quest Diagnostics

FAQ

What accuracy rates does Quest's new AD-Detect blood test show for Alzheimer's detection?

The AD-Detect blood test demonstrates 91% sensitivity and specificity, with 89% positive and negative predictive values in mild cognitive impairment populations.

How does Quest Diagnostics' AD-Detect test work to detect Alzheimer's?

The test measures blood levels of amyloid beta 42/40 and p-tau217, using proprietary mass spectrometry and immunoassay techniques to produce an AD-Detect Likelihood Score.

Where is Quest's AD-Detect blood test (DGX) currently available?

The test is available nationwide through Quest's 8,000 patient access points, except in New York state.

What advantages does Quest's AD-Detect blood test offer over traditional Alzheimer's testing methods?

AD-Detect is more affordable, less invasive, and more accessible than traditional amyloid PET imaging and cerebral spinal fluid testing.

What are the likelihood categories for Quest's AD-Detect test results?

In real-world testing, specimens were categorized as 42% high likelihood, 51% low likelihood, and 7% indeterminate likelihood for PET positivity.