Santos-Santos MA, et al. - In this study, the rates of positron emission tomography (PET) amyloid positivity in the main clinical variants of primary progressive aphasia (PPA) were determined. According to the current classification scheme, PPA variant diagnosis was correlated with Alzheimer's disease biomarker status, with the logopenic variant being associated with carbon 11–labeled Pittsburgh Compound-B positivity in more than 95% of cases. In addition, in the presence of a clinical syndrome highly predictive of frontotemporal lobar degeneration pathology, biomarker positivity for Alzheimer disease could be associated more with mixed pathology rather than primary Alzheimer's disease.