A paper in Nature demonstrates the measurement of high-performance plasma amyloid-β biomarkers by immunoprecipitation coupled with mass spectrometry. The ability of amyloid-β precursor protein (APP)669–711/amyloid-β (Aβ)1–42 and Aβ1–40/Aβ1–42 ratios, and their composites, to predict individual brain amyloid-β-positive or -negative status was determined by using amyloid-β-PET imaging of the donors of the samples as the criterion of presence or absence of disease. Accuracy of prediction was ~90%. The authors argue that these plasma biomarkers have cost–benefit and scalability advantages over current techniques, potentially enabling broader clinical access and efficient population screening.