Blood test holds promise for predicting when Alzheimer’s symptoms will start

Nature

by Heidi Ledford

February 20, 2026

AI-Generated Deep Dive Summary

A groundbreaking blood test has shown promise in predicting when Alzheimer’s symptoms might begin, offering a potential molecular “clock” to identify at-risk individuals before memory problems arise. The test focuses on abnormal tau proteins, which accumulate in the brains of people with Alzheimer’s long before symptoms like memory loss appear. This discovery, published in *Nature Medicine*, could revolutionize early intervention for the disease, allowing treatments to be administered when they are most effective—before irreversible brain damage occurs. The blood test detects a specific form of tau protein that circulates in the bloodstream and begins to build up in the brain years before Alzheimer’s symptoms develop. This abnormal tau protein forms tangled fibers that disrupt neural communication, leading to the progression of the disease. Current imaging techniques can also detect these tangles, but they are costly and cumbersome. A simple blood test could provide a more accessible and cost-effective way to monitor tau accumulation and predict symptom onset. Lead author Suzanne Schindler, a neurologist at Washington University School of Medicine in St. Louis, emphasizes that while the results are promising, further validation is needed. The study highlights the importance of early intervention for Alzheimer’s, as treatments are more likely to succeed when applied in the disease’s earliest stages. This could also streamline clinical trials by providing a clear biomarker to track disease progression. The implications of

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Originally published on Nature on 2/20/2026