Scientists have developed a simple blood test that measures the protein p-tau217 and predicts the onset of Alzheimer's symptoms with an accuracy of about 3-4 years.[1] This protein reflects the accumulation of amyloid and tau in the brain long before memory loss.[1] The study involved 603 elderly volunteers from two long-term studies: the WashU Medicine Knight Alzheimer Disease Research Center and the Alzheimer's Disease Neuroimaging Initiative.[1] The model works much like the rings of a tree, where p-tau217 levels indicate the time until symptoms appear.[1] The test is 96% accurate in identifying elevated levels of beta amyloid and 97% accurate in identifying tau.[5][6] Younger participants had a longer time between p-tau217 elevation and symptoms.[1] This advance may accelerate clinical trials of preventive drugs and enable personalized care.[1] The researchers shared the codes and created a web application to further improve the models.[1]