Linguistic markers in Parkinson’s disease (Smith et al., 2018)

Purpose: Early cognitive symptoms such as word-finding difficulty (WFD) in daily conversation are common in Parkinson’s disease (PD), but studies have been limited by a lack of feasible, quantitative measures. Linguistic analysis, focused on pauses in speech, may yield markers of impairment of cognition and communication in PD. The objective of this study was to evaluate the relationship of linguistic markers in semistructured speech to WFD symptoms and cognitive function in PD.

Method: Speech recordings of description of the Cookie Theft picture in 53 patients with PD without dementia and 23 elderly controls were analyzed with Praat software. Montreal Cognitive Assessment (MoCA; Nasreddine et al., 2005), category naming fluency, and confrontation naming tests were administered. Questionnaires rating WFD symptoms and cognitive instrumental activities of daily living were completed. We determined the relationships between (a) pause length and location, (b) MoCA score, and (c) WFD symptoms, using Pearson’s correlations and multivariate regression models.

Results: Compared with controls, patients with PD had more pauses within utterances as well as fewer words per minute and a lower percentage of well-formed sentences. Pauses within utterances differed significantly between PD–mild cognitive impairment and normal cognition (p < .001). Words per minute and percentage of well-formed sentences were predictive of MoCA in multivariate regression models. Pauses before verbs were associated with patient-reported severity of WFD symptoms (p = .006).

Conclusions: Linguistic markers including pauses within utterances distinguish patients with PD with mild cognitive symptoms from elderly controls. These markers are associated with global cognitive function before the onset of dementia. Pauses before verbs and grammatical markers may index early cognitive symptoms such as WFD that may interfere with functional communication.

Supplemental Material S1. Baseline characteristics of Parkinson’s disease (PD) with mild cognitive impairment (MCI) and normal cognition (NC).

Supplemental Material S2. Correlations between clinical, neuropsychological, and linguistic biomarkers and word-finding difficulty (WFD) symptoms.

Supplemental Material S3. Transcription conventions.

Smith, K. M., Ash, S., Xie, S. X., & Grossman, M. (2018). Evaluation of linguistic markers of word-finding difficulty and cognition in Parkinson’s disease. Journal of Speech, Language, and Hearing Research, 61, 1691–1699. https://doi.org/10.1044/2018_JSLHR-L-17-0304