# This blood test could detect Alzheimer's before symptoms start > A research team led by Dr. Carlos Cruchaga, of Washington University in St. Louis, has just published results in Nature Medicine on - Author: Maxime Marquette - Publisher: MadMax (https://mad-max.co) - Section: Editorial - Published: 2026-07-06 - Canonical URL: https://mad-max.co/en/article/ce-test-sanguin-pourrait-detecter-l-alzheimer-avant-les-premiers-symptomes ## Introduction: measured promise for millions of families ### A biological signal spotted years in advance A **research team** led by **Dr. Carlos Cruchaga**, of **Washington University in St. Louis**, has just published results in **Nature Medicine** on **July 1, 2026** that deserve careful attention rather than easy hype. The study shows that certain **circular RNA**, or **circRNA**, molecules detected in a simple **blood draw** can anticipate the onset of **Alzheimer's disease** symptoms several years before they appear clinically. This work relies on data from **1,221 people**, a sample large enough to give the findings statistical weight, without representing **absolute, definitive proof** applicable to the entire global population. ### Why this discovery changes the conversation Until now, **Alzheimer's** diagnosis relied largely on observing symptoms that had already set in, often at a point when **neurological damage** is difficult to reverse. An early, non-invasive, affordable **screening tool** could transform how **Western clinicians** approach this devastating disease. Researchers identified **34 distinct circRNAs** whose blood levels vary measurably before the first **cognitive signs** appear, opening an unprecedented **early-intervention window** for affected families. *This is the kind of statistic that, without being spectacular on its own, concretely changes things for thousands of families living in uncertainty about this disease.* *I'll say it upfront: news like this deserves measured enthusiasm, not headlines promising a miracle cure. Science advances in rigorous small steps, and that's exactly what deserves praise here.* ## Understanding what circular RNA is ### A molecule long ignored by research Unlike classic **messenger RNA**, which has a linear structure, **circRNA** forms a **closed loop**, a feature that makes it more stable and more resistant to degradation in the blood. This **biological stability** makes it a particularly interesting **biomarker** for diagnostic tests performed far from brain tissue itself. Long considered a biological byproduct with little use, **circRNA** has seen a major resurgence of scientific interest in recent years, particularly in the field of **neurodegenerative diseases**. ### The link between circRNA and brain degeneration Researchers at **Washington University** observed that certain specific **circRNAs** are produced in abnormal amounts in the **brains** of patients with **Alzheimer's**, and that these variations are also measurably reflected in **peripheral blood circulation**. This correspondence between what happens in the brain and what can be measured in a standard blood draw forms the **scientific basis** that makes this type of **screening** concretely feasible at scale. *This bridge between the brain and a simple vein in the arm is exactly the kind of biological shortcut preventive medicine needs to become truly accessible at scale.* *What strikes me is the patience it took to get here. Years spent studying a molecule considered secondary, until it may become one of the keys to early Alzheimer's screening.* ## The numbers that make this study credible ### Statistical precision that beats existing tools The **circRNA**-based model achieves an **area under the curve**, or **AUC**, of **0.945**, a statistical measure evaluating a test's ability to correctly distinguish sick people from healthy ones. By comparison, the current reference biomarker, the **pTau217 protein** used alone, only reaches an **AUC of 0.877**. When the two biomarkers are combined, precision climbs even higher, with a **combined AUC of 0.977**, a result approaching the **near-optimal threshold** considered in the scientific literature on diagnostic tests. ### A markedly higher progression risk People with abnormal levels of these **circRNAs** show a **hazard ratio of 2.92** for developing **clinical symptoms**, compared with a ratio of **1.81** for the **pTau217 protein** used alone. In concrete terms, this new marker identifies real danger with **enhanced reliability**. These numbers aren't just abstract statistics: they represent the difference between a late diagnosis, often after the appearance of hard-to-reverse damage, and an early intervention that could slow the disease's progression in some patients. *Numbers like these deserve to be repeated calmly rather than shouted on social media. Statistical rigor is precisely what distinguishes a real breakthrough from a mere announcement effect.* ## Validation across multiple independent cohorts ### The central role of the Knight-ADRC cohort The results were first established, then validated, within the **Knight-ADRC** cohort, comprising **551 participants** followed through the **research center** on Alzheimer's disease affiliated with **Washington University**. This **internal validation** step is essential to rule out results that could be due to **statistical chance**. The methodological soundness of this validation considerably strengthens the credibility of the findings, a crucial point in a field where many promising leads have collapsed under independent replication attempts. ### The A4 cohort, a large-scale generalization test Researchers then extended their validation to the **A4 cohort**, which includes **1,767 additional participants**, a much larger population that lets them check whether the results hold beyond the **initial study group**. This dual validation, across two independent cohorts of different sizes, is precisely the type of methodological rigor that distinguishes a reliable scientific discovery from an isolated, potentially non-reproducible observation. *It's this cross-validation step that reassures me the most in this study. We're not talking about one lucky group of patients, but results confirmed across nearly 2,300 people total.* ## An estimated early detection window ### Two to four years before the first symptoms According to the published data, abnormal **circRNA** levels begin to diverge from normal between **two and four years** before the first noticeable **cognitive symptoms** appear in patients. This **time window** is particularly valuable for **clinical research**. Detection this early opens the door to preventive interventions, whether lifestyle changes, enhanced medical follow-up, or eventually pharmacological treatments still in development that could be more effective when administered early. ### What this window changes for clinical trials One of the **major obstacles** in developing treatments for **Alzheimer's** has always been recruiting patients at a stage early enough for tested interventions to have a real chance of working. This new **blood test** could revolutionize **recruitment for future clinical trials**. By identifying at-risk people before significant neurological damage appears, researchers could finally test certain experimental treatments on a population where they statistically have a better chance of producing a measurable effect. *This might be the most underrated angle of this discovery: it doesn't just help warn patients, it could literally save decades of pharmaceutical research stalled by bad screening timing.* ## The limits that need to be named honestly ### This test isn't clinically available yet It's essential to say this plainly: this **circRNA**-based **blood test** remains, at this stage, a **research tool** not yet approved or available for routine clinical use. The transition from a lab discovery to a test accessible in a **doctor's office** generally takes several additional years. Medical regulatory bodies, in the United States and elsewhere in the West, require additional trials before such a test can be offered in standardized form to patients in a real clinical setting. ### A study population that still calls for caution Although the combined cohorts total nearly **2,300 people**, that number remains modest compared with the scale of the global population affected by **Alzheimer's disease**. Expanded studies involving more ethnically and geographically diverse populations will be needed before the findings can be fully generalized. This methodological caution takes nothing away from the value of the work accomplished, but it's a reminder that premature media hype would harm both the research's credibility and the legitimate expectations of patients' families. *I always prefer to stress these limits rather than let people believe a cure is around the corner. Public trust in science is built on honesty, not optimistic shortcuts.* ## The potential impact on millions of Western families ### The human and economic weight of Alzheimer's **Alzheimer's disease** affects millions of people across the West, imposing a considerable emotional burden on families and a growing economic cost on healthcare systems already under demographic pressure from aging populations. Reliable, affordable **early screening** could ease that burden by allowing calmer family, financial, and medical planning, well before the disease reaches a stage where the patient's decision-making capacity is compromised. ### A tool that would give patients and loved ones more time Beyond the statistics, this type of **blood test** could give families precious time back: time to organize care, to make important decisions together, and to enjoy the years when the patient's cognitive abilities remain largely intact. This human dimension, often absent from strictly scientific articles, deserves to be highlighted in a context where we talk too often about numbers and too rarely about the lives concretely affected by this disease. *This might be the most important part of this story: beyond the statistical curves, we're talking about families who could finally have time to prepare, instead of being caught off guard.* ## The next steps before clinical use ### Expanded clinical trials in preparation **Dr. Carlos Cruchaga's** team plans to extend its work to **larger, more geographically and ethnically diverse cohorts**, a step considered necessary before any submission to American and European **regulatory authorities** for clinical approval. These additional trials will need to confirm that the **blood test's** performance holds up across populations with varied genetic and environmental profiles, a standard requirement for any **diagnostic biomarker** intended for widespread clinical use. ### The role of Western health agencies In the United States, the **Food and Drug Administration** will need to evaluate this test's reliability and reproducibility before authorizing its commercialization, a process that generally takes several years for **molecular diagnostic** tools of this complexity. Equivalent agencies in **Europe** and **Canada** will likely follow a similar evaluation process, meaning access to this type of **screening** could vary significantly from one Western country to another in the coming years. ## Conclusion: a promising step, not a finish line ### A solid scientific advance in a demanding field This research led by **Dr. Carlos Cruchaga** and his team represents a methodologically solid advance in the quest for reliable early screening of **Alzheimer's disease**. The combination of **circRNA** and the **pTau217 protein** offers diagnostic precision that clearly surpasses currently available tools. But as with any scientific discovery of this nature, caution remains warranted: additional validation, expanded clinical trials, and a lengthy regulatory process still separate this research from widespread clinical application. ### What to remember while waiting for the next steps For families affected by **Alzheimer's**, this study offers reason for measured hope: science is progressing, methodically, toward tools that could one day transform how this disease is detected and managed in the West. In the meantime, the best approach remains following these developments with cautious optimism, giving in to neither excessive cynicism nor premature hype, two traps that regularly await media coverage of medical advances. **By Maxime Marquette, columnist** ## Columnist's transparency note ### Editorial stance I am not a journalist but a **columnist and analyst**. My expertise lies in observing and analysing the geopolitical, economic and strategic dynamics that shape our world. My work is to take political strategies apart, to understand global economic movements, to put the decisions of international actors in context and to offer analytical perspectives on the changes that are redefining our societies. I do not claim the cold objectivity of traditional journalism, which stops at reporting facts. **I claim analytical clarity**, rigorous interpretation and a deep understanding of the complex issues that concern us all. My role is to give meaning to the facts, to place them in their historical and strategic context, and to offer a critical reading of events. ### Method and sources This text keeps the basic distinction between **verified facts and interpretive analysis**. The rule never changes: a factual claim is published only when a verifiable source supports it, and the sources this article actually used are listed under **Sources**, never here. **Primary source families** used by the publication, when the story has them: official statements from governments and international institutions, public statements by political leaders, reports from intergovernmental organisations, dispatches from recognised international news agencies. **Secondary source families**: specialised publications, internationally recognised news media, analyses from established research institutions, reports from industry organisations. When an article cites statistical, economic or geopolitical data, it comes from the institutions that produce it (intergovernmental organisations, central banks, national statistics offices), and the exact institution is named under **Sources**. ### Nature of the analysis The analyses, interpretations and perspectives in the analytical sections of this article are a **critical, contextual synthesis** based on the information available, the trends observed and the expert comments cited in the sources consulted. My role is to interpret these facts, to set them in the context of today's geopolitical and economic dynamics, and to give them a coherent meaning within the larger story of the changes shaping our time. These analyses reflect expertise built through continuous observation of international affairs and an understanding of the strategic mechanisms that drive global actors. This article describes a documented state of affairs on its publication date, not a prediction: later developments may shift its outlook. No update is promised in advance; when an article is corrected or completed, the change is dated in the text. ## Sources ### Primary sources - News-Medical, medical research news — July 2026 - News-Medical, blood circRNAs may predict Alzheimer's before symptoms emerge — July 2, 2026 ### Secondary sources - News-Medical, Neurology section — 2026 - Medical Xpress, medical news — 2026 - Alzheimer's Association, news — 2026 - EurekAlert, health news — 2026 - National Institute on Aging, study on circular RNA and Alzheimer's — 2026 --- Source: Maxime Marquette, MadMax. When citing, name the author and link https://mad-max.co/en/article/ce-test-sanguin-pourrait-detecter-l-alzheimer-avant-les-premiers-symptomes