Palmqvist S, Janelidze S, Stomrud E, et al. - In two prospective, cross-sectional, multicenter studies, researchers investigated the exactitude of plasma β-amyloid (Aβ) and tau measured using fully automated assays together with other blood-based biomarkers to identify cerebral Aβ. The first cohort included 842 participants (513 cognitively unimpaired [CU], 265 with mild cognitive impairment [MCI], and 64 with Alzheimer disease [AD] dementia) from the Swedish BioFINDER study and the validation cohort involved 237 participants (34 CU, 109 MCI, and 94 AD dementia) from a German biomarker study. Plasma Aβ42 and Aβ40 measured using Elecsys immunoassays prognosticated Aβ status in all stages of AD with comparable accuracy in a validation cohort. Their accuracy can be further enhanced by investigating the APOE genotype. Potential future applications of these blood tests involve prescreening of Aβ positivity in clinical AD trials to reduce the costs and number of PET scans or lumbar punctures.