Speech function in persons with Parkinson\u27s disease: effects of environment, task and treatment

Parkinson’s Disease (PD) is a degenerative neurological disease affecting aspects of movement, including speech. Persons with PD are reported to have better speech functioning in the clinical setting than in the home setting, but this has not been quantified. New methodologies in ambulatory measures of speech are emerging that allow investigation of non-clinical settings. The following questions are addressed: Is speech different between environments in PD and in healthy controls? Can clinical tasks predict speech behaviors in the home? Is treatment proven effective by measures in the home? What can we glean from methods of measurement of speech function in the home? The experiment included 13 persons with PD and 12 healthy controls, studied in the clinical and home environments, and 7 of those 13 persons with PD participated in a treatment study. Major findings included: Spontaneous speech intelligibility, not intensity, was the differentiating factor between persons with PD and healthy controls. Intelligibility and intensity were not related. Both groups presented with higher sentence intensity in the home environment. Spontaneous speech intelligibility in the clinic was related to spontaneous speech intelligibility in the home. The Sentence Intelligibility Test emerged as the best predictor of spontaneous speech intelligibility in the home. Differences between pilot treatment groups measured in the home on intensity and intelligibility were not large enough to make a clinical trial feasible. Individual differences may account for many of these results, for example more severely impaired patients may have shown different data. Drawing conclusions regarding the home environment via measures outside the home should be carefully considered. Ambulatory measures of speech are a viable option for studying speech function in non-clinical settings, and technology is advancing. Further investigation is needed to develop methodologies and normative values for speech in the home