Association of amyloid-β CSF/PET discordance and tau load five years later

Objective: To investigate the association between discordant amyloid-β PET and CSF biomarkers at baseline and the emergence of tau pathology 5 years later.

Methods: We included 730 ADNI participants without dementia (282 cognitively normal, 448 mild cognitive impairment) with baseline [18F]Florbetapir PET and CSF Aβ42 available. Amyloid-β CSF/PET status was determined at baseline using established cut-offs. Longitudinal data was available for [18F]florbetapir (Aβ) PET (baseline to 4.3±1.9 years), CSF (p)tau (baseline to 2.0±0.1 years), cognition (baseline to 4.3±2.0 years), and [18F]flortaucipir (tau) PET (measured 5.2±1.2 years after baseline to 1.6±0.7 years later). We used linear mixed modelling to study the association between amyloid-β CSF/PET status and tau pathology measured in CSF or using PET. Additionally, we calculated the proportion of CSF+/PET- participants who during follow-up (i) progressed to amyloid-β CSF+/PET+, and/or (ii) became tau-positive based on [18F]flortauci...