Spoken Language Production in Huntington's and Parkinson's Diseases

The purpose of this study was to investigate the presence and nature of spoken language deficits in Huntington's (HD) and Parkinson's (PD) diseases. Specifically, the study examined whether (a) the spoken language abilities of patients with HD or PD differ from those of age-matched control participants with no brain damage, (b) HD and PD are associated with similar spoken language profiles, and (c) the spoken language abilities of patients with HD or PD are related to the severity of their motor speech deficits, cognitive impairments, or both. All participants completed picture description tasks and a battery of cognitive and motor speech tests. Syntactic, quantitative, and informativeness measures of spoken language were analyzed. In terms of syntax, patients with HD produced shorter utterances, a smaller proportion of grammatical utterances, a larger proportion of simple sentences, and fewer embeddings per utterance than their non-brain-damaged peers. The HD group also produced utterances that were shorter and syntactically simpler than those of the PD group, despite similar performances on the cognitive and motor speech tests. The only syntactic difference between the PD group and their control group was that patients with PD produced a smaller proportion of grammatical sentences. Although the patient and control participants tended to produce similar amounts of verbal output, less of what the patients said was considered informative. Correlations between language measures and test battery results suggested that the spoken language abilities of patients with HD or PD are related to a variety of neuropsychological and motor speech changes. The implications of these findings for the clinical management of HD and PD are discussed.