Fluid biomarkers for neurodegenerative diseases: a comprehensive update.

Fluid biomarkers are revolutionizing the diagnosis and management of neurodegenerative diseases by enabling earlier diagnosis and disease monitoring. In particular, blood-based biomarkers have emerged as a minimally invasive and scalable alternative to cerebrospinal fluid analysis. Recent advances in blood-based tau biomarkers have shown high diagnostic accuracy for Alzheimer’s disease (AD). Other neurodegenerative diseases—such as synucleinopathies, frontotemporal lobar degeneration, limbic-predominant age-related TDP-43 encephalopathy (LATE), and amyotrophic lateral sclerosis—pose substantial challenges due to their heterogeneous clinical presentations and the current absence of robust biomarkers for hallmark pathologies. Nonetheless, promising candidate markers are emerging for improved disease characterization and staging. Technological innovations, including single-molecule arrays (Simoa), advanced mass spectrometry workflows and nucleic acid linked immune-sandwich assay (NULISA) have markedly enhanced the sensitivity and precision of biomarker quantification from low-concentration biological matrices. More recently, the development of fully automated platforms shows great promise for routine measurement of blood-based biomarkers in clinical settings. Despite this progress key challenges remain, including the need for improved assay reproducibility, standardization, and the optimization of clinical workflows. In this review, we provide a comprehensive update on recent progress in fluid biomarker research across AD and major neurodegenerative diseases, highlight technological advances in detection methods, and discuss current challenges and opportunities for clinical translation.