A new study brings hope for earlier and more accessible diagnosis of Alzheimer’s disease. Two blood tests from Quest Diagnostics have demonstrated high accuracy in identifying the disease’s pathology in people with symptoms.
This development could reduce the reliance on more invasive and expensive methods like PET scans and spinal fluid analysis. The study was published in Neurology® Clinical Practice, a journal of the American Academy of Neurology.
The Challenge of Diagnosing Alzheimer’s
Diagnosing Alzheimer’s disease has long been a complex process. It often requires expensive imaging or invasive procedures to confirm the presence of amyloid plaques, a key indicator of the disease.
Nearly 7 million Americans live with Alzheimer’s disease. That number is expected to double by 2060. Finding a more straightforward and accessible diagnostic tool is a major public health priority.
Two New Blood Tests Show Promise
The study, a collaboration between Quest Diagnostics and the University of Florida, evaluated two multi-biomarker blood tests. The research involved 215 individuals with mild cognitive impairment or Alzheimer’s disease.
One test, which Quest plans to release in early 2026, analyzes three key biomarkers: amyloid beta (Aβ) 42/40, phosphorylated tau (p-tau) 217, and the ApoE4 proteotype. The second test, launched in April 2025, omits the ApoE4 marker.
High Accuracy and Reliability
Both tests demonstrated impressive performance, meeting the standards set by the Alzheimer’s Association and the Global CEO Initiative on Alzheimer’s Disease (CEOi). These organizations recommend a sensitivity and specificity of approximately 90% for confirmatory blood tests.
The study showed both tests achieved 91% sensitivity and 91% specificity. This high level of accuracy suggests the tests can reliably confirm Alzheimer’s pathology.
| Test Configuration | Positive Predictive Value (PPV) | Negative Predictive Value (NPV) | Indeterminate Rate |
| Three Biomarkers (Aβ 42/40, p-tau217, ApoE4) | 88% | 91% | 10% |
| Two Biomarkers (Aβ 42/40, p-tau217) | 87% | 91% | 15% |
Positive predictive value (PPV) indicates the likelihood of a true positive result. Negative predictive value (NPV) shows the likelihood of a true negative. The low indeterminate rates mean fewer ambiguous results, giving doctors and people with dementia more confidence in the findings.
“This study demonstrates that scalable blood-based testing can meet rigorous standards for establishing Alzheimer’s disease pathology, supporting diagnosis and advancing patient care for Alzheimer’s disease in the intended use patients,” said Dr. Michael Racke, Senior Medical Director of Neurology at Quest Diagnostics.
What This Means for People with Dementia
The availability of accurate and accessible blood tests for Alzheimer’s disease has several important implications. It can lead to earlier diagnosis, which is crucial for planning care and treatment.
It may also reduce the need for more burdensome and costly procedures. A Quest Diagnostics report found that 94% of physicians believe blood tests would be more cost-effective for the healthcare system [1].
The Future of Alzheimer’s Diagnosis
These findings represent a significant step forward in the fight against Alzheimer’s disease. As research continues, blood-based biomarkers will likely play an even larger role in the diagnosis and management of the disease.
Quest Diagnostics continues to work on innovative diagnostic tools to help evaluate Alzheimer’s and other brain diseases. These new tests offer a powerful tool to help improve the lives of people affected by this challenging condition. More info here: https://www.questdiagnostics.com/healthcare-professionals/about-our-tests/neurological-disorders/alzheimers
References
[1] PR Newswire. (2025, October 27). New Study Demonstrates Accuracy of Two Quest AD-Detect® Tests for Alzheimer’s Disease Diagnosis. https://www.prnewswire.com/news-releases/new-study-demonstrates-accuracy-of-two-quest-ad-detect-tests-for-alzheimers-disease-diagnosis-302594686.html
