Propositional speech in unselected stroke: The effect of genre and external support

Abstract

Distinguished from nominal language, propositional language generation refers to the spontaneous and voluntary aspect of language that introduces novel concepts to a specific context. Propositional language can be impaired in a range of neurological disorders, including stroke, despite well-preserved nominal language. Although external support can increase speech rate in patients with reduced propositional speech, no specific investigation of propositional speech has been carried out in unselected stroke patients. The current study investigated propositional language in an unselected post-acute stroke group (N = 18) with mild cognitive impairment and prominent executive dysfunction, but without significant aphasia. Specifically, we investigated whether genre or external support affected the number of words, sentences, and novel ideas produced, compared to healthy controls (N = 27). Results showed that discourse genre was not associated with differential performances. By contrast, speech quantity increased without external support although, for stroke patients, speech novelty decreased. Overall, the novelty deficit in unselected stroke patients highlights the importance of assessing cognition and propositional speech. Our findings suggest that for stroke patients with mild cognitive deficits, including executive dysfunction, introducing external support improved speech quality but not quantity. Implications for both assessment and rehabilitation of social communication are discussed.

Keywords:

• Language generation
• Genre
• External support
• Selection
• Novelty

We thank J. Mikli, L. Ling and M. Mariani for assistance in patient recruitment and M. Libera for assistance with some neuropsychological assessments. This research was supported by a small project grant from the National Stroke Foundation (Australia) and GR is supported by an Australian Research Council Discovery Early Career Researcher Award [DE120101119].