Development of a robust blood‐based multi‐pathway biomarker assay for early screening and classification of Alzheimer’s disease

Background Alzheimer's disease (AD) is a devastating neurodegenerative disease with delayed diagnosis until the manifestation of symptoms. Although the emergence of blood‐based biomarkers offers hope for easy detection of AD, existing AD‐associated blood biomarkers, known as the “blood ATN biomarkers”, mainly capture the pathological hallmarks of AD, overlooking other AD‐associated biological processes such as inflammation and vascular dysfunctions. Therefore, developing a blood‐based biomarker assay that captures dysregulation beyond the ATN biomarkers may help advance early detection and staging of AD, enabling a comprehensive examination of the disease status Method We leveraged ultrasensitive proteomic technology to develop a blood‐based, multiplex biomarker assay for AD. This assay simultaneously measures the levels of 21 blood proteins associated with different biological pathways, including neurodegeneration, inflammation, innate immunity, vascular functions, and metabolic activities. Moreover, we developed an AD risk scoring system by integrating the level changes of these 21 proteins in a machine learning‐based model. The performance of this 21‐protein biomarker assay in AD classification and indication of AD‐related endophenotypes was evaluated in three independent cohorts Result We showed that this 21‐protein biomarker assay accurately classifies AD (AUC = 0.9407–0.9867) and mild cognitive impairment (MCI) (AUC = 0.8434–0.8945). It also indicates amyloid pathology in Chinese and European populations. Moreover, this assay simultaneously evaluates changes in five biological processes, providing comprehensive assessment of disease status and revealing heterogeneity of AD among individuals. Notably, dysregulations of biological processes upon AD progression are different between Chinese and European populations, particularly in biological pathways related to inflammation and vascular functions. Conclusion Our findings demonstrate the utility of a blood‐based multi‐pathway biomarker assay for early screening and staging of AD in clinical settings and provide insights for patient stratification and the development of precision medicine.