Authors: Spencer KA, Morgan KW, Blond E
Title: Dopaminergic medication effects on the speech of individuals with Parkinson’s disease
Source: Journal of Medical Speech Language Pathology 2009 17(3): 125-144
Year: 2009
Research Design: Case Series

Individuals with idiopathic Parkinson's disease (IPD) have long been treated with dopamine-based medications such as levodopa. While dopaminergic medication is considered to be quite successful in treating the limb motor deficits of IPD, its effect on speech is unclear. Fifteen participants with IPD provided speech samples of a monologue and reading passage while optimally medicated and while off dopaminergic medications for 15 hours. Ten experienced speech-language pathologists (SLPs) perceptually rated speech samples using a visual analog scale for the dimensions of intelligibility, naturalness, and voice quality. Speech rate, as measured by words per minute, also was assessed for change with medication state. No significant group differences were found between medication conditions for the perceptual ratings, though marked changes occurred for individual speakers. Moreover, participants were found to speak at a significantly slower rate while on medications. Results are discussed in terms of speaker characteristics, the viability of the perceptual rating methodology, and the possible influence of cognitive functioning on speech rate.

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