Biomarkers.

Area of Science:

• Neuroscience
• Neurology
• Biomarkers

Background:

• Prior studies link cerebrospinal fluid p-tau181 to olfactory and auditory impairments.
• The predictive value of Alzheimer's disease (AD) pathology for neurosensory decline is not well understood.

Purpose of the Study:

• To investigate the cross-sectional and longitudinal relationship between amyloid and tau (A/T) status and neurosensory functions (odor identification and central auditory processing).
• To validate findings using both PET imaging and plasma-based A/T biomarkers.

Main Methods:

• 233 participants from the PREVENT-AD cohort underwent amyloid and tau PET scans, odor identification (UPSIT), and central auditory processing (DSI) tests.
• Plasma biomarkers (Aβ42, Aβ40, p-tau217) were analyzed in a subset (n=208).
• Statistical analyses included Kruskal-Wallis, Dunn's tests, and linear mixed effects models to assess group differences and longitudinal changes.

Main Results:

• PET-based analysis showed lower odor identification (OI) scores in amyloid-positive/tau-negative (A+T-) individuals compared to amyloid-negative/tau-negative (A-T-).
• Plasma-based classification revealed lower OI scores in amyloid-positive/tau-positive (A+T+) individuals compared to A+T- and A-T-.
• Longitudinally, the most significant decline in OI was observed in the A+T+ group, particularly when using plasma biomarkers.

Conclusions:

• Alzheimer's disease pathology, specifically the presence of both amyloid and tau (A+T+), is associated with declining odor identification.
• Further research should explore these associations in other neurosensory domains like vision and gustation.