Taoufik Boubga, Abdellah Taous, Tarik Boulahri, Maha Ait Berri
Journal: Medpeer Publisher
ISSN: 3066-2737
Volume: 2
Issue: 10
Date of Publication: 2025/10/28
Background: Alzheimer’s disease (AD), the leading cause of dementia, is characterized by amyloid beta (Aβ) plaques, tau tangles, and neuronal loss. Early diagnosis remains difficult, especially in prodromal phases. Biomarkers from biological fluids are critical for detecting pathology, aiding diagnosis, and monitoring progression.
Methods: This narrative review summarizes two decades of evidence on biological fluid biomarkers in AD, identified from PubMed, Scopus, and Web of Science using terms including “Alzheimer’s disease,” “biological fluid,” “cerebrospinal fluid,” “plasma,” “serum,” “urine,” and “saliva.” Studies included evaluated biomarkers with diagnostic or prognostic potential.
Results: Cerebrospinal fluid (CSF) biomarkers—Aβ42, total tau (t-tau), and phosphorylated tau (p-tau)—are the most validated and form the basis of the AT(N) framework. Blood biomarkers have advanced with ultrasensitive assays; plasma p-tau isoforms (p-tau181, p-tau217, p-tau231) show high accuracy in distinguishing AD and correlate with PET imaging. Neurofilament light chain (NfL) in CSF and blood is a robust marker of neurodegeneration. Salivary, urinary, tear, and exosomal biomarkers remain experimental but promising due to their non-invasive collection.
Conclusion: Biological fluid biomarkers have transformed AD research and diagnosis. While CSF remains the reference standard, blood-based p-tau isoforms are emerging as scalable, non-invasive tools for early detection and monitoring. Broader clinical use will require assay standardization and integration into multimodal frameworks.
Alzheimer’s disease; biomarkers; cerebrospinal fluid; blood biomarkers; plasma p-tau; neurofilament light chain; diagnosis; dementia.
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