A head-to-head comparison of plasma biomarkers to detect biologically defined Alzheimer in a memory clinic

INTRODUCTIONBlood-based biomarkers for Alzheimers disease (AD) have been widely studied, but direct comparisons of several biomarkers in clinical settings remain limited. METHODSIn this cross-sectional study, plasma biomarkers from 197 participants in the BIODEGMAR cohort at Hospital del Mar (Barcelona) were analysed. Participants were classified based on AD cerebrospinal fluid (CSF) core biomarkers. We assessed the ability of plasma p-tau181, p-tau217, p-tau231, t-tau, and A{beta}42/40 to classify A{beta} status. RESULTSPlasma p-tau biomarkers had a greater diagnostic performance and larger effect sizes compared to t-tau and A{beta}42/40 assays in detecting biologically defined AD. Among them, plasma p-tau217 consistently outperformed the others, demonstrating superior AUC. Furthermore, p-tau217 showed the strongest correlation between plasma and CSF levels, underscoring its potential as a reliable surrogate for CSF biomarkers. DISCUSSIONSeveral plasma biomarkers, targeting different epitopes and using different platforms, demonstrated high performance in distinguishing biologically defined AD in a memory clinic setting.