Characteristics of speech disfluency in Parkinson disease

The purpose of this study was to describe speech disfluency characteristics in a group of 32 individuals with Parkinson disease (PD). Individuals with PD read a standard passage, and percentages of within-word and between-word disfluencies were calculated. The disfluency percentages exhibited by the individuals with PD were significantly greater than age-matched control speakers. Similarity was found between PD-related disfluencies and disfluencies seen in developmental stuttering, as the PD participants produced primarily motoric-based within-word disfluencies, including both repeated movements and fixed postures. A relationship was also found between self-ratings of medication effectiveness and disfluency levels, and this relationship is interpreted relative to the dopamine hypothesis of stuttering. Finally, significant reductions in within-word disfluencies were seen during a clear-speech task, along with an increase in disfluency levels during a monologue compared to a reading task.