Verb production in the nonfluent and semantic variants of primary progressive aphasia: The influence of lexical and semantic factors

Abstract

Differential patterns of impairment with respect to noun and verb production have been observed in the nonfluent and semantic variants of primary progressive aphasia. However, the factors influencing this discrepancy remain unclear. The present study evaluates verb retrieval in primary progressive aphasia using a naming task and a story completion task. Findings indicate that patients with the semantic variant are influenced by familiarity, frequency, and age of acquisition in both object and action naming, whereas patients with the nonfluent variant are not. Surprisingly, there were no differences in either group between object and action naming, presumably because the lists were well matched on pertinent variables. In the story completion task, greater impairment in semantically heavier than in semantically lighter verbs was observed for the semantic variant, and grammaticality and verb tense agreement was significantly lower in the nonfluent variant. The present findings suggest that lexicosemantic attributes affect verb production in the semantic variant, whereas both lexicosemantic and syntactic attributes affect verb production in the nonfluent variant.

Keywords:

• Verb production
• Semantic dementia
• Nonfluent primary progressive aphasia
• Semantic weight
• Lexical factors
• Naming
• Verb story completion task

The authors would like to thank Amy Lewis, Shayna Sparling, Danna Rybko, and Ashleigh Wishen for help with testing subjects, as well as Kate Orgill and Bruna Seixas Lima for the transcriptions.

Canadian Institutes of Health Research (CIHR) [grant number 82744]; Toronto Rehabilitation Institute (K.M.); Department of Medicine at the University of Toronto and Sunnybrook Health Sciences Center, the Brill Chair in Neurology, the Brain Sciences Research Program, and Sunnybrook Research Institute (S.E.B.).

Notes

¹ There is a third variant, termed logopenic PPA. The number of logopenic patients recruited for this study was too few in number (n = 5). In any event, the question of interest in this study is most relevant to nfPPA and svPPA variants.

² In Barde et al. (2006), the patient versus patient + state contrast provided less consistent results. As such, this contrast was excluded from our analyses, resulting in the analysis of responses to 33 of the 41 stories.

³ For this analysis, data from one control participant were excluded, as the percentage of grammatically correct sentences that he produced was 2 standard deviations below the control group mean.