To assess concordance among neuropsychological assessment (NPS), ¹⁸F-fluorodeoxyglucose-PET (FDG-PET), CSF and Amyloid-PET (Amy-PET) in Primary Progressive Aphasia (PPA).

We included 60 subjects with diagnosis of PPA. All patients underwent NPS, FDG-PET scan and Amy-PET scan or CSF biomarkers measurement. Our sample included 10 nfvPPA, 17 svPPA, 22 lvPPA and 11 u/mPPA. Subjects were defined as Aβ⁺ if they had at least one positive AD biomarker.

10% of nfvPPA, 24% of svPPA and 96% of lvPPA were Aβ⁺. Concordance between Aβ1-42 and Amy-PET was 68%, but significantly improved when considering Aβ1-42/40 ratio (78.94%). Concordance between clinico-funtional diagnosis and AD biomarkers was 84%. We analyzed discordant cases and found that among four nfvPPA/svPPA subjects with positive Amy-PET, two subjects did not perform CSF analysis and one svPPA subject had positive Amy-PET but negative CSF biomarkers. In one svPPA subject, AD patholgy was confirmed both by Amy-PET and CSF. One lvPPA subject had normal CSF Aβ1-42 concentration, but Aβ1-42/40 and Amy-PET were not performed. 55% of u/mPPA were Aβ⁺. In this group, two uPPA had no AD pathology, 100% of nfv/lvPPA and 40% of sv/lvPPA were Aβ⁺.