The effects of speech therapy and pharmacological treatments on voice and speech in Parkinson s disease: a review of the literature.

The purpose of this paper was to examine the effects of speech therapy and various pharmacological treatment approaches on the voice and speech of persons with Parkinson s disease (PD). Approximately 80% of PD patients have voice and speech problems including reduced vocal intensity, reduced vocal pitch, monopitch and monoloudness, and imprecise articulation. Research prior to 1970's had not demonstrated significant improvements following speech therapy. However, recent research has shown that speech therapy (when persons with PD are optimally medicated) has proven to be the most efficacious therapeutic method for improving voice and speech function. Across research studies, pharmacological methods of treatment in isolation do not appear to significantly improve voice and speech function in PD. In a single subject study, however, the dopamine agonist Mirapex was shown to have beneficial effects on vocal intensity. Possible explanations for the differential responses to treatment are discussed. It is suggested that the goal of future studies should be investigations of the effects of combined treatment approaches.