Clinical laboratories should note the growing role of blood-based biomarkers in neurodegenerative disease detection.
Researchers at Washington University School of Medicine in St. Louis have developed a blood-test–based model that may predict when symptoms of Alzheimer’s disease are likely to begin—potentially giving clinical researchers a powerful tool to accelerate preventive treatment studies.
It is just the latest development in the rapidly evolving area of Alzheimer’s research that the general public is becoming increasingly aware of. Clinical laboratory professionals should continue to monitor this progress.
The study, published in Nature Medicine, demonstrated that the predictive models could estimate the onset of Alzheimer’s symptoms within a margin of roughly three to four years. By estimating when cognitive decline may begin, the approach could help researchers enroll patients in clinical trials at the most informative stages of disease progression, shortening study timelines and improving the evaluation of therapies designed to delay or prevent symptoms.
In September 2025, Dark Daily reported that new clinical guidelines from the Alzheimer’s Association recommend that Alzheimer’s blood tests achieve at least 90% sensitivity and specificity before they can replace established diagnostic tools such as amyloid PET imaging or cerebrospinal fluid testing. The recommendations aim to standardize clinical use of emerging biomarkers—particularly p-tau and amyloid-beta assays—while helping clinicians and laboratories determine when blood-based tests can be used for diagnosis or as triage tools in Alzheimer’s disease evaluation.
Blood Biomarker p-tau217 Provides Early Clock for Alzheimer’s Disease Progression
Alzheimer’s disease currently affects more than seven million Americans, and the economic burden continues to grow. According to the Alzheimer’s Association, health and long-term care costs related to Alzheimer’s and other forms of dementia are projected to reach nearly $400 billion in 2025. Because symptoms often appear years after underlying brain changes begin, researchers have increasingly focused on identifying biomarkers that can detect and track disease earlier.
The new predictive models rely on measuring plasma levels of a protein biomarker known as p-tau217, which reflects the accumulation of amyloid and tau proteins in the brain—two pathological hallmarks of Alzheimer’s disease. These misfolded proteins begin building up many years before symptoms emerge. By analyzing patterns of p-tau217 in blood samples, researchers created what they describe as a biological “clock” that tracks disease progression.
“Our work shows the feasibility of using blood tests, which are substantially cheaper and more accessible than brain imaging scans or spinal fluid tests, for predicting the onset of Alzheimer’s symptoms,” said senior author Suzanne E. Schindler, MD, PhD, an associate professor in the WashU Medicine Department of Neurology. Schindler noted that these models could allow clinical trials of potentially preventive treatments to be performed within a shorter time period.
To develop the models, investigators analyzed data from 603 older adults participating in two major longitudinal research initiatives: the WashU Knight Alzheimer Disease Research Center and the multi-site Alzheimer’s Disease Neuroimaging Initiative. Participants lived independently and were monitored over time for biomarker changes and cognitive decline.
The researchers found that elevated p-tau217 levels in blood correlated strongly with amyloid and tau buildup observed through PET brain imaging. Using this relationship, they estimated how long it typically takes for individuals with elevated biomarker levels to develop cognitive symptoms.
Age Influences Alzheimer’s Symptom Onset as Blood Biomarker Model Gains Validation
Interestingly, the timeline varied by age. Participants who first showed elevated p-tau217 at younger ages experienced longer delays before symptom onset. For example, individuals with elevated levels at age 60 tended to develop symptoms roughly 20 years later, whereas those whose biomarker levels rose at age 80 developed symptoms about 11 years later. The finding suggests that younger brains may be more resilient to the early stages of neurodegeneration.
The predictive approach also proved robust across multiple diagnostic assays measuring p-tau217, including the commercially available PrecivityAD2 blood test. Researchers noted that broader use of blood-based biomarker testing could offer a more accessible and cost-effective alternative to PET imaging or spinal fluid analysis.
For clinical laboratories and diagnostic developers, the findings highlight the growing role of blood-based biomarkers in neurodegenerative disease detection and management. While additional research will be required before such models are used in routine clinical care, investigators say the technology could significantly improve the design of preventive Alzheimer’s trials—and eventually help physicians identify patients most likely to benefit from early interventions.
This article was created with the assistance of Generative AI and has undergone editorial review before publishing.
—Janette Wider
