P4‐068: Amyloid‐positive Cognitive Impairment Is Less “alzheimer's‐like” in the Absence of Tau
Year: 2019
Type: article
Abstract: The ATN framework for Alzheimer's Disease (AD) classifies individuals based on beta-amyloid (A+/A-), tau (T+/T-), and neurodegeneration (N+/N-). Amyloid pathology precedes significant tangle pathology, with the latter being linked to neurodegeneration and symptom onset. Thus, cognitively impaired A+T- likely have alternate pathologies driving symptoms. 79 amyloid-positive (A+) ADNI participants (cut off: florbetapir PET SUVR ≥1.11) with MCI or dementia and 234 controls were included. A cut-off of AV-1451 PET SUVR ≥1.21 in extrahippocampal medial temporal lobes (T+/T-) was derived using 90%-sensitivity threshold in A- cognitively normal controls (n=221). A+T- and A+T+ were compared to each other and controls on hippocampal volumes, regional cortical thicknesses, and cognitive profiles. A+T+ (n=53) and A+T- (n=26) were similarly represented in proportions of MCI versus dementia-level impairment, but A+T- was significantly older than A+T+ (Table 1). For A+T-, age-and-intracranial-volume-adjusted hippocampal volume (mean=2577±350mm) did not differ from controls’ (mean=2542± 337mm, p=0.624), while for A+T+, mean hippocampal volume (2204±361mm) was significantly smaller (p<0.0001). Compared to controls’ precuneus thickness (mean=2.01mm±0.42), cortical thinning was evident in both A+T- (mean=1.77±0.46mm, p=0.018) and A+T+ (mean=1.69±0.35mm, p<0.0001). Compared to controls’ middle frontal gyrus (MFG) thickness (mean=2.50±0.56mm), cortical thinning was present in both A+T- (mean=1.90±0.38mm, p<0.0001) and A+T+ (mean=1.99±0.32mm, p<0.0001). Compared to A+T+, A+T- performed better on delayed recall measures, similarly on category fluency and processing speed (Trails A), but worse in absolute terms on Trails B. Performance on all of these cognitive tests was significantly worse for both A+T- and A+T+ compared to controls.
Source: Alzheimer s & Dementia
Institution: University of Pennsylvania
Language: English
Subfield: Psychiatry and Mental health
Field: Medicine
Domain: Health Sciences
Open Access status: bronze
OpenAlex ID: W2980648907