Overlapping and distinguishing features of descriptive speech in Richardson variant of progressive supranuclear palsy and non-fluent progressive aphasia

Background Progressive supranuclear palsy (PSP) has overlapping clinical features with primary progressive aphasia (PPA). Our study aimed at comparing classical PSP phenotype – Richardson syndrome (PSP) with three different variants of PPA in terms of descriptive speech. Methods Fifty-eight patients participated in the study: 18 with the clinical diagnosis of PSP-RS, 14 with nfvPPA, eight with logopenic variant of PPA (lvPPA), 8 with semantic variant of PPA (svPPA) and 10 with Alzheimer's disease (AD). Results Lexical access in descriptive speech is comparably good in PSP-RS and nfvPPA. However, speech rate is faster in PSP-RS than in nfvPPA and patients with PSP-RS are more likely to construct complex sentences than individuals with nfvPPA. Conclusion Overlapping linguistic features were noted between PSP-RS and nfvPPA, but not with lvPPA or svPPA.