A nonspeech investigation of tongue function in Parkinson's disease

BACKGROUND: Nonspeech investigations of tongue function in persons with Parkinson's disease (PD) have generally reported impaired tongue strength, endurance, and fine force control. However, these investigations did not specifically evaluate the relative contribution of age effects to the deficits in tongue function observed. Furthermore, the relationship between these nonspeech measures of tongue function and the speech disorder present in PD remains equivocal. Therefore, the current study investigated the strength, rate of repetitive movement, fine force control, and endurance of the tongue in three groups of participants. METHODS: Participants in the study included 14 older adults with PD and imprecise consonant articulation, 11 neurologically healthy older adults, and 15 neurologically healthy young adults. All participants were assessed using a comprehensive nonspeech assessment battery of tongue function. RESULTS: The results of the investigation revealed similar levels of tongue strength, rate of repetitive movement, and endurance between the persons with PD and the older control participants. Significant age effects were noted, with both groups demonstrating significantly reduced functioning on those measures when compared to young control participants. However, the three participant groups had similar levels of fine force control. No relationship was found between the nonspeech measures of tongue function employed and the severity of consonant imprecision. CONCLUSION: The nonspeech measures used failed to provide useful diagnostic information regarding the physiologic basis of perceived articulatory dysfunction in the persons with PD who were examined.