Blood biomarkers for clinical applications in Alzheimer's disease: A narrative review
Huijun Li, Zhe Wang
Abstract
Alzheimer's disease is a prevalent neurodegenerative disorder that imposes a significant burden on both patients and society. Currently, the primary methods for diagnosing Alzheimer’s disease include imaging techniques and cerebrospinal fluid analysis. However, these methods have several limitations, including their invasive nature, high costs, and the challenges associated with their widespread use. In contrast, blood testing is non-invasive, cost-effective, and easily accessible, making it a promising alternative for the early diagnosis, monitoring, and prediction of Alzheimer’s disease. The aim of this review is to summarize the research progress on blood biomarkers for Alzheimer’s disease from multiple perspectives, including the background of Alzheimer’s disease research, the establishment of diagnostic criteria, detection techniques, and specific biomarkers. This review emphasizes that the National Institute on Aging and the Alzheimer’s Association have proposed the amyloid-tau-neurodegeneration (ATN) classification system, which categorizes biomarkers into three dimensions: amyloid-beta plaques, tau protein, and neurodegeneration. The ATN system provides a comprehensive reflection of the pathological processes associated with Alzheimer’s disease. Recent technologies, such as single molecule array (Simoa) and superconducting quantum interference device immunomagnetic reduction assays, have emerged as promising techniques for the high-sensitivity identification of blood biomarkers involved in Alzheimer’s disease. Biomarkers such as amyloid-beta, tau protein, neurofilament light chain, exosomes, and glial fibrillary acidic protein have been widely studied for their potential in predicting, diagnosing, and monitoring Alzheimer's disease. Combining multiple biomarkers can enhance the accuracy of diagnosing Alzheimer’s disease. Despite the significant potential of blood biomarkers in the diagnosis of Alzheimer’s disease, several challenges remain. First, differences in the techniques used by various laboratories, as well as factors such as sample collection and processing, can hinder the comparison and reproducibility of results. Second, the collection, processing, and storage of blood samples may affect the accuracy of test results. Finally, individual differences, genetic background, comorbidities, and disease stage also need to be considered to improve diagnostic accuracy. Therefore, it is essential to establish standardized operating procedures and quality control standards, develop effective data analysis methods, and conduct large-scale cohort studies and prospective research to advance the application of blood biomarkers in the diagnosis of Alzheimer’s disease.