Alzheimer Disease—What’s in a name?

Alzheimer Disease—What’s in a name?
JAMA Neurology; Ronald C. Petersen, PhD, MD; Elizabeth Mormino, PhD; Julie A. Schneider, MD, MS; 11/24
Back in 2018, the National Institute on Aging (NIA)–AA [Alzheimer Association] group proposed a biological definition of AD [Alzheimer Disease] stating that if a person had the biomarker evidence of brain amyloid (A) and tau (T), the pathologic hallmarks of the disease, the patient had AD irrespective of the person’s clinical state. In their recent 2024 revision, they maintain a biological definition but have extended it to incorporate more recent biomarkers for AD; ... positivity on core 1 biomarkers that indicate the crossing of a specific amyloid threshold on amyloid positron emission tomography (PET), cerebrospinal fluid, and foreseeably, plasma biomarkers. A major question pertains to the requirement for tau in the definition [as] the AA group argues that the vast majority of individuals who have amyloid-positive PET scans have some tau pathology. Furthermore, the AA group proposes a clinical staging scheme that provides a framework to define the frequent mismatch between AD biomarker positivity (and underlying neuropathology) and the clinical expression of the disease, often an indicator of mixed pathologies or resilience. Importantly, although the AA group does base the AD diagnosis on biomarker positivity, they do not currently advise testing in asymptomatic persons in a clinical setting.