Background: Associations of plasma total tau levels with future risk of AD have been described.
Objective: To examine the extent to which plasma tau reflects underlying AD brain pathology in cognitively healthy individuals.
Methods: We examined cross-sectional associations of plasma total tau with 11C-Pittsburgh Compound-B (PiB)-PET and 18F-Flortaucipir (FTP)-PET in middle-aged participants at the community-based Framingham Heart Study.
Results: Our final sample included 425 participants (mean age 57.6± 9.9, 50% F). Plasma total tau levels were positively associated with amyloid-β deposition in the precuneus region (β±SE, 0.11±0.05; p = 0.025). A positive association between plasma total tau and tau PET in the rhinal cortex was suggested in participants with higher amyloid-PET burden and in APOEɛ4 carriers.
Conclusions: Our study highlights that plasma total tau is a marker of amyloid deposition as early as in middle-age.
Keywords: Alzheimer’s disease; Framingham Heart Study; PET; amyloid-β; plasma total tau; tau.