Molecular Testing in Early Diagnosis and Clinical Assessment of Alzheimer’s Disease: A Narrative Review

Alzheimer’s disease (AD) is a progressive neurodegenerative disorder and one of the leading causes of dementia worldwide. With the increasing prevalence driven by population aging, there is a growing demand for early, accurate, and biologically grounded diagnostic approaches. Advances in molecular diagnostics have created new opportunities for early disease detection, staging, and monitoring of therapeutic responses, reshaping contemporary diagnostic workflows. Validated cerebrospinal fluid biomarkers—amyloid-β, total tau, and phosphorylated tau—form the core of current biologically based diagnostic criteria, while blood-based biomarkers such as plasma p-tau and neurofilament light chain are gaining prominence due to their minimally invasive nature and scalability. Advanced imaging techniques, including amyloid and tau positron emission tomography, further enhance diagnostic accuracy and support differentiation of AD from other neurodegenerative disorders. Despite these advances, the clinical implementation of molecular diagnostics remains limited by methodological heterogeneity, biological variability, and the lack of standardized analytical and clinical frameworks. Addressing these translational challenges is essential for integrating molecular biomarkers into routine clinical practice and for enabling reliable, large-scale screening and early diagnosis of AD.