Summary: A new study establishes the long-term prognostic power of the blood-based biomarker p-tau217. The analysis reveals that asymptomatic individuals presenting with very high baseline p-tau217 concentrations face an absolute 38% risk of developing cognitive impairment within 5 years, escalating to 78% within 10 years.
This predictive capability operates entirely independent of amyloid PET plaque profiles and APOE4 genetics, providing a validated screening standard to select high-risk candidates for targeted Alzheimer’s disease prevention trials.
Key Facts
- The 5-Year and 10-Year Risk Trajectories: The study successfully converted raw p-tau217 biomarker levels into individual risk forecasts. Cognitively healthy older adults who registered “very high” baseline p-tau217 levels demonstrated a 38% absolute risk of developing cognitive impairment within 5 years. Over a 10-year horizon, that predictive risk escalated dramatically to 78%.
- Total Independence from Other Risk Factors: Crucially, the p-tau217 biomarker predicted future cognitive decline entirely independent of other established risk profiles. Its mathematical accuracy held firm even when accounting for the physical presence of amyloid-beta plaques on PET scans or high-risk genetic variations like the APOE4 allele.
- Current Asymptomatic Clinical Restraint: Despite the high accuracy of the test, Dr. Reisa Sperling emphasizes that currently available blood tests are not recommended for healthy, asymptomatic individuals in everyday clinical practice. Because there are no approved disease-modifying therapies for asymptomatic pre-clinical stages, a positive test cannot alter standard medical options.
- The Clinical Standard Recommendation: For any individual discovering a high-risk profile today, the foundational medical guidance remains strictly behavioral and preventative: regular cardiovascular exercise, a highly nutritious diet, strict sleep prioritization, and aggressive overall metabolic wellness tracking.
- The “Cholesterol Test” Target: The ultimate goal of the Mass General Brigham team is to mature p-tau217 testing into the neurological equivalent of a standard cardiovascular cholesterol screening, providing an accessible tool that safely guides proactive monitoring and early clinical interventions years before a devastating event occurs.
- Gateway to Clinical Prevention Trials: The primary immediate application for p-tau217 testing is the rapid, low-cost screening of ideal candidates for ongoing disease-modifying therapy clinical trials. By identifying individuals with high risk before symptoms manifest, researchers can test preventive treatments when the brain is most receptive to preservation.
Source: Mass General
A blood test for the biomarker phosphorylated tau 217 (p-tau217) recently received federal clearance, but questions have emerged around the extent to which such tests can accurately predict whether a cognitively healthy individual will go on to develop cognitive impairment—a key symptom of Alzheimer’s disease.
A new, international study involving researchers across three continents and led by experts from the Mass General Brigham Neuroscience Institute sheds new light on the prognostic value of such tests.
The study found that cognitively unimpaired individuals with very high levels of the biomarker had a 38% absolute risk of developing cognitive impairment over the next five years—and higher risk over the next 10 years.
Results are presented at the Alzheimer’s Association International Conference and simultaneously published in JAMA.
“We do not yet have disease-modifying treatments for people who find out they are at high risk for developing cognitive impairment due to Alzheimer’s disease, which is why we don’t recommend currently available blood tests for asymptomatic individuals.
Today, our medical advice would remain the same regardless of test results: exercise regularly, maintain a healthy diet, and prioritize sleep and overall wellness,” said senior and corresponding author Reisa Sperling, MD, a neurologist with the Mass General Brigham Neuroscience Institute.
“But the preventive care landscape could change rapidly if ongoing trials of disease-modifying therapies prove beneficial. In the future, these tests could help identify those who might benefit most from these treatments. Our long-term goal is to get us to where cholesterol testing is in predicting your risk of a heart attack.”
To conduct their study, investigators pooled data from across six observational and clinical trial studies based in North America, Japan, and Australia. The studies included 2,684 cognitively unimpaired older adults. Blood samples were tested for p-tau217 levels and PET imaging was conducted when participants enrolled in the studies to get a baseline reading. Participants received annual follow-ups to assess cognitive function. The earliest enrollment in one of the studies was in 2004, and the most recent follow-up was in 2025.
The research team charted participants’ cognitive trajectories, quantifying their risk of developing cognitive impairment over time. Approximately 478 participants progressed to cognitive impairment. Higher p-tau217 levels at baseline were significantly associated with cognitive impairment. Individuals with very high p-tau217 levels had a 38% risk of developing cognitive impairment over five years. This risk grew with time, reaching 78% over 10 years. However, data were much sparser for 10-year outcomes and beyond.
“This is a critical step toward better understanding what p-tau217 can tell us about a person’s risk for cognitive impairment,” said lead author Rachel F. Buckley, PhD, a cognitive neuroscientist with the Mass General Brigham Neuroscience Institute. “What really sets this work apart is that it estimates an individual’s level of risk for cognitive impairment. We harmonized data across six cohorts, creating a large and varied data set, and still found consistent results showing how p-tau217 informs risk over time.”
Researchers found that the blood test predicted risk independent of other known risk factors, including amyloid-beta plaques that can appear on PET scans and known genetic risk factors (such as APOE4). While the study’s design has many strengths, it is still limited by selection bias and focuses on relatively short-term risks, rather than over a lifetime. Future work is needed to validate the findings in broader and more representative populations. By following participants over longer periods, researchers will be able to further refine individual risk estimates.
“Today, p-tau217 can help identify people at high risk for future Alzheimer’s dementia for participation in prevention trials,” said Sperling. “As these trials move forward, individualized estimates, including the biomarker’s prognostic value, could guide earlier treatment and monitoring decisions.”
Authorship: In addition to Sperling and Buckley, Mass General Brigham authors include Diana L. Townsend, Colin J. Birkenbihl, Madison Cuppels, Gillian T. Coughlan, Mabel T. Seto, Jane A. Brown, Michael J. Properzi, Merle C. Hönig, Annie Li, Aaron P. Schultz, Jasmeer Chhatwal, Hyun-Sik Yang, Steven Arnold, Pia Kivisäkk, Brian Healy, Jorge Garcia Condado, Wai-Ying Wendy Yau, Michelle Farrell, Rebecca E. Amariglio, Dorene M. Rentz, Kathryn V. Papp, and Keith A. Johnson. Additional authors include Bryan D. James, Sid O’Bryant, Robert A. Rissman, Melissa Petersen, Jessica Z. K. Caldwell, Tobey Betthauser, Julie Elisabeth Oomens, Maria Carrigan, Sterling C. Johnson, Oliver Langford, Ron Brookmeyer, Timothy J. Hohman, Michael Donohue, and Paul S. Aisen.
Disclosures: Buckley reported receiving grants from the National Institutes of Health (NIH) outside the submitted work. Sperling reported receiving grants from NIH (A4; R01 AG063689, U24AG057437), GHR Foundation, and Alzheimer’s Association during the conduct of the study; consulting for AbbVie, AC Immune, Acumen, Alector, Apellis, Biohaven, Bristol Myers Squibb, Ionis, Immunobrain, Janssen, Novo Nordisk, Oligomerix, Prothena, Roche, Therini, and Vaxxinity; and public-private partnership clinical trial funding from Eisai and Eli Lilly outside the submitted work. Additional author disclosures can be found in the JAMA paper’s disclosures section.
Funding: This study was funded in part by the National Institutes of Health (R01AG079142, DP2AG082342, U01 AG024904, R01AG054073, R01AG058533, R01AG070862, P41EB015922, U19AG078109, R01AG027161, R01AG021155, P30AG062715, U19AG010483, R01AG063689, P01 AG036694, P41EB015896, S10RR021110, S10RR023401, S10RR023043, P30AG062421), the U.S. Department of Defense (W81XWH-12-2-0012), Eli Lilly, the Alzheimer’s Association, Accelerating Medicines Partnership, the GHR Foundation, an anonymous foundation, private donors, and in-kind support from Avid, Cogstate, Albert Einstein College of Medicine, Foundation for Neurologic Diseases, and Meso Scale Diagnostics.
Key Questions Answered:
A: Phosphorylated tau 217 (p-tau217) is a specific, highly sensitive protein biomarker that accumulates in the blood when Alzheimer’s disease begins its silent, destructive progression in the brain. Historically, checking for these molecular changes required incredibly expensive, hard-to-access Positron Emission Tomography (PET) brain scans or painful lumbar punctures to collect spinal fluid. A reliable blood test for p-tau217 means we can spot the physical signs of Alzheimer’s pathology through a simple, low-cost blood draw at a standard local clinic.
A: This is a vital clinical boundary. Right now, modern medicine does not possess an approved, disease-modifying treatment that can stop or reverse Alzheimer’s changes in someone who shows zero cognitive symptoms. If a completely healthy person takes this test and discovers they have a high risk of developing impairment in five years, it can cause severe anxiety and emotional distress without offering a medical cure to fix it. Until preventative therapies are officially proven and available, a positive test cannot change your daily medical care.
A: This study provides the exact missing roadmap needed to run successful prevention trials. To find a drug that prevents Alzheimer’s symptoms from ever starting, scientists have to test new therapies on people who are currently healthy but at a very high risk of developing the disease soon. By proving that p-tau217 accurately identifies who has a 38% risk over five years and a 78% risk over ten years, this blood test allows researchers to instantly find the ideal participants for clinical trials, dramatically accelerating our search for a true preventative cure.
Editorial Notes:
- This article was edited by a Neuroscience News editor.
- Journal paper reviewed in full.
- Additional context added by our staff.
About this Alzheimer’s disease research news
Author: Noah Brown
Source: Mass General
Contact: Noah Brown – Mass General
Image: The image is credited to Neuroscience News
Original Research: Open access.
“Prognostic Value of Blood-Based P-Tau217 Levels for Progression to Cognitive Impairment” by Aaron P. Schultz, Annie Li, Brian Healy, Bryan D. James, Colin J. Birkenbihl, Diana L. Townsend, Dorene M. Rentz, Gillian T. Coughlan, Hyun-Sik Yang, Jane A. Brown, Jasmeer Chhatwal, Jeffrey R. Fine, Jessica Z. K. Caldwell, Johnna R. Swartz, Jorge Garcia Condado, Julie Elisabeth Oomens, Kathryn V. Papp, Keith A. Johnson, Kevin Volkel, Kyle Tomek, Liam Paninski, Lorenzo Posani, Mabel T. Seto, Madison Cuppels, Maria Carrigan, Madison Cuppels, Marilize Richter-Cottle, Melissa Petersen, Merle C. Hönig, Michael Donohue, Michael J. Properzi, Mirjam Münch, Myles N. Arrington, Oliver Langford, Paul S. Aisen, Pia Kivisäkk, Rachel F. Buckley, Rebecca E. Amariglio, Reisa A. Sperling, Robert A. Rissman, Ron Brookmeyer, Rozanne Kruger, Samuel P. Muscinelli, Shuqi Wang, Stefano Fusi, Sterling C. Johnson, Steven Arnold, Timothy J. Hohman, Tobey Betthauser, Wai-Ying Wendy Yau, for the Alzheimer’s Disease Neuroimaging Initiative, Anti-Amyloid Treatment in Asymptomatic Alzheimer’s (A4) and Longitudinal Evaluation of Amyloid Risk and Neurodegeneration (LEARN) studies, Harvard Aging Brain Study (HABS), Health & Aging Brain Study – Health Disparities (HABS-HD), and Wisconsin Registry for Alzheimer’s Prevention (WRAP). JAMA
DOI:10.1001/jama.2026.12556
Abstract
Prognostic Value of Blood-Based P-Tau217 Levels for Progression to Cognitive Impairment
Importance
Blood-based biomarkers for Alzheimer disease, particularly plasma phosphorylated tau 217 (p-tau217), accurately reflect early Alzheimer disease brain pathology in cognitively unimpaired individuals, but estimates of absolute risk of progression to cognitive impairment across multiple cohorts are needed.
Objective
To estimate absolute risk of progression to cognitive impairment and rates of cognitive decline based on plasma p-tau217 across cognitively unimpaired older adults.
Design, Setting, and Participants
Longitudinal cohort study using harmonized data from 2684 cognitively unimpaired older adults (defined within cohort) across 6 observational and clinical trial cohorts based in North America, Japan, and Australia. The earliest enrollment was in 2004, with most recent follow-up in 2025.
Exposure
Baseline plasma p-tau217.
Main Outcomes and Measures
The primary outcome was time to progression to cognitive impairment (mild cognitive impairment, dementia, or 2 consecutive global Clinical Dementia Rating scores ≥0.5). The secondary outcome was longitudinal change on the latent Preclinical Alzheimer Cognitive Composite (PACC; higher values indicate better performance).
Results
Among the 2684 participants (median [IQR] age, 69.6 [66.2-74.2] years; 1697 [63%] female), there were 478 events of progression to cognitive impairment over a median follow-up of 5.4 years (maximum follow-up of 13.5 years). Each 1-SD increase in baseline p-tau217 level was associated with an increased risk of progression to cognitive impairment (hazard ratio, 1.38 [95% CI, 1.30-1.46]), and the association remained significant after adjustment, including β-amyloid positron emission tomography scan Centiloids (hazard ratio, 1.32 [95% CI, 1.24-1.41]). Participants with high (1.1-2.4 SD) and very high (>2.5 SD) baseline p-tau217 had 24% (95% CI, 20%-28%) and 38% (95% CI, 33%-43%) absolute risk of progression over 5 years, respectively, and risk was markedly higher over 10 years, although longer-term estimates were constrained by limited data. Elevated p-tau217 was also associated with faster cognitive decline based on change in latent PACC score. Among the overall sample, baseline latent PACC scores ranged from −0.8 to 2.7. The 5-year annualized decline for the very high p-tau217 group was −0.07 latent PACC units/y (95% CI, −0.10 to −0.05), relative to 0.03 units/y (95% CI, 0.02-0.04) in the low p-tau217 group.
Conclusions and Relevance
In a pooled sample of multiple selected cohorts of cognitively unimpaired older adults, higher plasma p-tau217 levels were consistently associated with increased risk of clinical progression and accelerated cognitive decline. By providing time-specific absolute risk estimates, these findings support the potential of p-tau217 for prognostic model development, with direct implications for future trial design. Further validation in unselected populations is needed to inform individual prognosis and clinical decision-making in cognitively unimpaired individuals.
