Examining the relationship between task-switching and speech errors in Parkinson’s disease

Research Objectives: To establish the link between cognitive flexibility deficits and errors in speech production in Parkinson’s disease (PD). A secondary goal is to show that this relationship exists despite the presentation of “normal” overall cognitive functioning on a standard screening test (Montreal Cognitive Battery; MoCA).

Design: Regression (between-subjects)

Setting: University

Participants: Fifteen people with PD and 15 adult controls participated in this study. All were native speakers of American English, had no upper respiratory tract infections, and passed depression and hearing screenings. People with PD varied on a continuum of overall disease and speech severity. Controls had no history of hearing, speech-language, or neurological disorders. All study procedures were approved by the Institutional Review Board.

Interventions: n/a

Main Outcome Measures: 1) Metrics of cognitive flexibility (reaction times, error rates)
2) MoCA scores, speech errors (articulation errors, stuttering-like disfluencies, and other disfluencies) and
3) Speech rate

Results: Results show that people with PD would present with impaired cognitive flexibility (slower reaction times to switch demands compared to controls) despite falling within normal range on standard clinical screenings of cognition (MoCA) and that people with PD and controls show an inverse relationship between cognitive flexibility and the number of errors during speech production with group differences in both flexibility and speech error rates occurring.

Conclusions: Our findings suggest that impairments in cognition in PD may occur earlier than previously thought and may only be apparent on more sensitive tests of cognitive flexibility that are typically not performed as standard-of-care. A relationship between cognitive flexibility and speech errors suggests a role of cognitive flexibility during speech-motor control. These deficits should be considered when recommending therapy and designing interventions.

Author(s) Disclosures: Funding for this work is through an internal grant by Seton Hall University. No other relevant disclosures.