The 2024 NIA-AA biological definition of Alzheimer's disease: linking biomarkers to clinical practice.
Level 5 - mechanism / opinion, no new human data
Narrative review of diagnostic frameworks and biomarker advances with no systematic search or new empirical human data.
PubMed 41756762 · doi:10.3389/frdem.2026.1736297
What was done
This review traced the historical evolution of Alzheimer's disease (AD) diagnostic frameworks from the 1984 NINCDS-ADRDA clinical criteria through the 2011 revisions to the 2024 NIA-AA biological criteria. The authors synthesized recent developments in fluid (e.g., p-tau217, mid-region p-tau) and PET imaging biomarkers, expanded multi-modal profiling systems, and evaluated the clinical implications of co-pathologies, staging, and disease-modifying therapies.
What was found
The abstract presents no quantitative experimental numbers or effect estimates. It outlines the conceptual shift of the 2024 NIA-AA criteria, which define AD by biological pathology rather than clinical symptomatology. The framework updates the AT(N) system to an AT1T2NISV multimodal profile: Core-1 biomarkers (A, T1) establish diagnosis, Core-2 biomarkers (T2) support biological staging, and additional markers evaluate neurodegeneration (N), inflammation (I), α-synuclein (S), and vascular injury (V).
Why it matters
It explains how fluid and imaging biomarkers can biologically define and stage Alzheimer's disease independently of symptom presentation, framing current approaches to precision medicine.
Limits
As a narrative review, this work reports no primary empirical data, systematic search criteria, or pooled diagnostic metrics. The abstract does not report quantitative performance measures (such as sensitivity, specificity, or predictive values) for the discussed biomarkers.
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