Analysing syntactic productions in semantic variant PPA and non-fluent variant PPA: how different are they?

Abstract

Background: It is commonly held that individuals with the nonfluent/agrammatic variant of primary progressive aphasia (nfvPPA) show difficulties with syntactic production, but that the production of individuals with the semantic variant of primary progressive aphasia (svPPA) is intact. Much of this evidence to date is derived from results of unconstrained language production tasks. There is emerging evidence however that the syntactic production of individuals with svPPA may not be as accurate as was previously thought. Aims: The goal of the current study was to investigate the sentence production abilities of participants with nfvPPA and svPPA (in comparison to matched control participants) using a constrained task eliciting syntactically complex utterances. Methods & Procedures: A constrained picture description task, which elicited active, passive, dative, and dative–passive sentences, was administered to three groups of participants (individuals with nfvPPA and svPPA and matched controls) on up to three occasions over a span of 2 years. Responses were scored andanalysed using analyses of variance, crossing group and sentence type, for each of the testing times. Outcomes & Results: Results show that both the nfvPPA and svPPA groups demonstrated more difficulty with the passive and dative– passive structures compared to the active and dative sentence structures and compared to control participants, although the difficulties were more severe and were observed earlier for the participants with nfvPPA. Both groups also demonstrated difficulty with noun production, although in this case the difficulty was more severe for the participants with svPPA. Conclusions: The current group study provides new evidence of a syntactic production difficulty in individuals with svPPA, notably when complex structures are elicited. The source of the difficulty, whether it is due to a primary syntactic impairment and/or as an extension of the impairment to their semantic system, remains unclear. However, the impairment appears to differ from that of participants with nfvPPA. Further clarification of this syntactic production impairment can yield potentially useful information for researchers and clinicians in this field.