Information Content and Efficiency in the Spoken Discourse of Individuals With Parkinson's Disease Purpose This study compared the information content and information efficiency of spoken language in individuals with Parkinson's disease (PD) to a healthy comparator group. Method Nineteen participants with PD and 19 healthy older adults completed the prospective, cross-sectional study. In the primary analysis, 2 language samples elicited by ... Research Article
Research Article  |   September 19, 2018
Information Content and Efficiency in the Spoken Discourse of Individuals With Parkinson's Disease
 
Author Affiliations & Notes
  • Angela Roberts
    Roxelyn and Richard Pepper Department of Communication Sciences and Disorders, Northwestern University, Evanston, IL
  • Danielle Post
    Roxelyn and Richard Pepper Department of Communication Sciences and Disorders, Northwestern University, Evanston, IL
  • Disclosure: The authors have declared that no competing interests existed at the time of publication.
    Disclosure: The authors have declared that no competing interests existed at the time of publication. ×
  • Correspondence to Angela Roberts: angela.roberts@northwestern.edu
  • Editor-in-Chief: Sean Redmond
    Editor-in-Chief: Sean Redmond×
  • Editor: Carl Coelho
    Editor: Carl Coelho×
Article Information
Special Populations / Older Adults & Aging / Language Disorders / Attention, Memory & Executive Functions / Language / Research Articles
Research Article   |   September 19, 2018
Information Content and Efficiency in the Spoken Discourse of Individuals With Parkinson's Disease
Journal of Speech, Language, and Hearing Research, September 2018, Vol. 61, 2259-2274. doi:10.1044/2018_JSLHR-L-17-0338
History: Received September 11, 2017 , Revised January 8, 2018 , Accepted May 4, 2018
 
Journal of Speech, Language, and Hearing Research, September 2018, Vol. 61, 2259-2274. doi:10.1044/2018_JSLHR-L-17-0338
History: Received September 11, 2017; Revised January 8, 2018; Accepted May 4, 2018

Purpose This study compared the information content and information efficiency of spoken language in individuals with Parkinson's disease (PD) to a healthy comparator group.

Method Nineteen participants with PD and 19 healthy older adults completed the prospective, cross-sectional study. In the primary analysis, 2 language samples elicited by standardized protocols were analyzed for group differences using standard discourse informativeness measures including main events (MEs; Wright, Capilouto, Wagovich, Cranfill, & Davis, 2005) analyzed as %MEs and correct information units (CIUs; Nicholas & Brookshire, 1993) analyzed as %CIUs and CIUs/min. In exploratory analyses, the following were examined: (a) associations among conceptual (%MEs) and lexical (%CIUs and CIUs/min) measures and (b) associations among informativeness measures and age, education, disease severity/duration, global cognition, speech intelligibility, and a verb confrontation naming measure.

Results In the primary analysis, the PD group differed significantly from the control group on conceptual (%MEs) and lexical measures of content (%CIUs) and efficiency (CIUs/min). In exploratory analyses, for the control group %MEs were significantly correlated with CIUs/min. Significant associations among conceptual and lexical measures of informativeness were not found in the PD group. For controls, there were no significant correlations between informativeness measures and any of the demographic or speech/cognitive/language variables. In the PD group, there was a significant and positive association between CIUs/min and Dementia Rating Scale–Second Edition scores (Mattis, 2001). A significant but negative correlation was found between CIUs/min and motor severity scores. However, %MEs and verb naming were significantly and positively correlated.

Conclusions Individuals with PD without dementia demonstrated reduced discourse informativeness that reflects disruptions to both conceptual and lexical discourse processes. In exploratory analyses, reduced efficiency of information content was associated with global cognition and motor severity. Clinical and research implications are discussed within a Cognitivist framework of discourse production (Sheratt, 2007).

Acknowledgments
This study was funded by grants to the first author from the Canadian Institutes of Health Research (Canadian Institutes Health Research Fellowship Award, Canadian Institutes of Health Research Prize in Aging, CIHR 201202MFE-278501-181687) and Parkinson Society Canada (Graduate Student Award). The researchers gratefully acknowledge the contributions of Shalane Basque, Bracia Eaton, and Hannah Hinkle for their contributions in the transcription, coding, and reliability procedures. The researchers extend gratitude to Heather Harris Wright, who graciously provided access to the scoring and training materials for the main event portion of the protocol.
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