Objective: To evaluate the effects of syntax complexity on the frequency of verbal disfluencies in individuals with PD and healthy controls (HC) during spontaneous speaking tasks.

Background: Cognitive impairments in PD can manifest as language problems [1, 2]. Individuals with PD also exhibit higher rates of verbal disfluencies (pauses, reformulations, sound/word repetitions). Researchers suggest that verbal disfluencies indicate language planning issues in PD [3-5]. However, few studies have directly tested this hypothesis.

Method: 19 PD (on-state; H&Y 2-3.5) and 19 HC without MCI/dementia completed a neuropsychology, motor speech, and spoken discourse battery. Language samples were collected using standardized picture sequences. Researchers blinded to group allocation orthographically transcribed and coded samples for verbal disfluencies and syntax complexity [6]. Frequency and type of verbal disfluency were analyzed using ANOVAs with group and syntax complexity (whether the disfluency occurred in a simple or complex sentence) as independent variables.

Results: There were no group effects on words/minute, total utterances, speech intelligibility, or proportion of complex utterances, suggesting that the two groups did not differ on measures of language productivity or syntax complexity. Groups differed on the proportion of unfilled pauses (PD higher), p < .01. Both groups produced significantly more revisions, filled pauses (“uhm,” “uh”), p = .01, and sound/word repetitions, p = .01, in sentences with complex syntax structures. However, the non-significant interaction effect suggests that the impact of syntax planning did not differ between the groups.

Conclusion: These results indicate that syntax planning demands affect PD and HC similarly, manifesting as verbal disfluencies vs. as syntax simplification or syntax errors. The clinical and theoretical implications of these findings for PD and typical aging will be discussed. We are currently investigating this aim in 160 PD individuals with and without MCI/dementia (ONDRI trial).

References: 1. Murray, L. (2008). LANGUAGE AND PARKINSON’S DISEASE. Annual Review of Applied Linguistics, 28, 113-127. doi:10.1017/S0267190508080100 2. Roberts, A., & Post, D. (2018). Information Content and Efficiency in the Spoken Discourse of Individuals With Parkinson’s Disease. Journal of Speech, Language, and Hearing Research, 61(9), 2259-2274. 3. McNamara, P., Obler, L. K., Au, R., Durso, R., & Albert, M. L. (1992). Speech monitoring skills in Alzheimer’s disease, Parkinson’s disease, and normal aging. Brain and Language, 42(1), 38-51. 4. Illes, J., Metter, E. J., Hanson, W. R., & Iritani, S. (1988). Language production in Parkinson’s disease: Acoustic and linguistic considerations. Brain and language, 33(1), 146-160. 5. Illes, J. (1989). Neurolinguistic features of spontaneous language production dissociate three forms of neurodegenerative disease: Alzheimer’s, Huntington’s, and Parkinson’s. Brain and language, 37(4), 628-642. 6. Thompson, C. K., Shapiro, L. P., Tait, M. E., Jacobs, B., Schneider, S., & Ballard, K. (1995). A system for the linguistic analysis of agrammatic language production. Brain and Language, 51(1), 124-129.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/verbal-disfluencies-in-parkinsons-disease-spoken-discourse-as-a-function-of-syntax-complexity/