Evolving Alzheimer’s Disease Clinical Practice: Updated Diagnostic Criteria, Fluid Biomarkers, and Special Considerations for Anti-Amyloid Therapies

OBJECTIVE: This review overviewed the recent paradigm shifts in the diagnosis and management of Alzheimer's disease (AD), emphasizing the 2024 Alzheimer's Association (AA) revised criteria, advances in cerebrospinal fluid (CSF) and blood-based biomarkers (BBMs), and practical considerations for anti-amyloid monoclonal antibody therapy. METHODS: We conducted a narrative appraisal of consensus frameworks (2018 National Institute on Aging-Alzheimer's Association [NIA-AA] amyloid, tau, and neurodegeneration [AT(N)] and the 2024 AA criteria), clinical practice guidance from AA released in 2025, regulatory status of CSF and BBMs. Intended-use settings (triage vs. confirmatory) of BBMs and implementation of anti-amyloid anti-body treatments (lecanemab or donanemab) in real-world practice in Korea were also reviewed. RESULTS: The 2024 AA criteria define AD biologically and designate A and T as core biomarkers; Core 1 biomarkers can establish AD irrespective of symptoms, whereas Core 2 biomarkers refine staging. A two-cutoff BBM strategy (positive/intermediate/negative) reduces misclassification and guides confirmatory CSF/positron emission tomography (PET) or retesting. BBMs now approach CSF/PET accuracy for amyloid detection, enable triage and, in selected settings, confirmation, and show utility for monitoring treatment response. Integration of clinical stages (1-6) with biological stages (A-D) clarifies syndrome-pathology discordance. Special scenarios-maintenance after induction, APOE ε4 homozygotes, Down syndrome, and serious mental illness-require individualized risk-benefit assessment. In South Korea, constrained access to tau PET and some BBMs necessitates Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition, Text Revision-anchored evaluation with selective biomarker testing. CONCLUSION: Biomarker-oriented diagnosis and anti-amyloid therapies are reshaping AD care. Priorities include rigorous validation of BBMs across populations, equitable access to core biomarkers, safety strategies, and real-world evidence to implement maintenance and special-population care pathways.