The present study aimed to investigate the effects of dopaminergic medication on voice, speech motor functions, and motor impairment in patients with Parkinson's disease.
Twenty-five individuals with Parkinson disease underwent comprehensive assessment of voice, speech, and motor functions in levodopa medication ON and medication OFF conditions.
Frenchay Dysarthria Assessment and Unified Parkinson's Disease Rating Scale-III were used to evaluate speech motor and motor functions, respectively.
An improvement in lip and laryngeal functioning was found in the medication ON over medication OFF state in both males and females with Parkinson disease.
UPDRS-III scores reduced from the OFF state to the ON state, and no change in dysarthria severity or VHI was found in either gender or medication condition. No correlation was found between speech motor function and motor function or between VHI and acoustic parameters of voice in either medication condition.
Improvement in motor symptoms with levodopa was predominantly observed when compared with the minor improvements in a few aspects of speech motor function and vocal parameters. The results of this study suggest the need for speech therapy as a nonpharmacological treatment method for speech impairments in Parkinson disease.