| dc.description.abstract | Purpose: Motor speech and cognitive dysfunction are both common clinical symptoms in the degenerative diseases of Huntington’s disease (HD) and Parkinson’s disease (PD). Though there is variability in speaking rate in both HD and PD, little is understood about the impact of cognitive decline on speaking rate in these populations. This study aimed to evaluate performance on measures of speech timing for individuals with HD, PD, and matched neurotypical controls across reading tasks. Methods: A total of 27 patients with HD, 21 patients with PD and 37 matched neurotypical control participants completed this study (21 HDNC, 16 PDNC). All participants completed a series of sentence and paragraph reading tasks, rate modification tasks (i.e., reading aloud at fast, habitual, and slow rates), and the Symbol Digit Modalities Test (SDMT). Measures of articulation rate, speech rate, and mean pause length were calculated for each task and rate condition. The change score across habitual to slow and habitual to fast rate conditions was calculated for each measure of speech timing across groups and tasks. Results: The HD group presented with slower habitual rates, increased mean pause length, and reduced ability to modify rate compared to matched controls. The PD group performed more similarly to the matched controls in the PDNC group on measures of habitual rate and rate modification. In general, increased habitual speech rate, decreased mean pause length, and greater degrees of rate modification were observed on the sentence compared to the paragraph reading task. All groups demonstrated the ability to manipulate rate measures to some degree on both tasks with the HD group presenting with the lowest ability to alter rate. SDMT performance may be more related to habitual rate rather than ability to modify rate with low cognitive scores associated with reduced habitual rate and increased pausing. Conclusions: The findings of this study support an association between cognitive ability and measures of speech timing in HD and PD. Further research should investigate task-dependent performance across a larger variety of speech production elicitation tasks. | |
