High-Level Language Production in Parkinson's Disease: A Review <s> Fluency Impairments. <s> Abstract The hypokinetic dysarthria of Parkinson's disease (PD) has been described extensively. In contrast, patterns of hesitation and the language structure in spontaneous speech of the PD patient have not been investigated, although several studies have shown language-related abnormalities in word naming, word generation, and verbal recall. In the present study, 10 male Parkinson's patients and 10 normal male speakers were compared in a reading and spontaneous speaking paradigm for acoustic and linguistic features. Among acoustic measures, fundamental frequency and relative intensity differentiated PD from control subjects, consistent with reported features of hypokinetic dysarthria. The striking observations among linguistic measures differentiating PD from control subjects were an increase in the number of (a) silent hesitations per minute, (b) abnormally long silent hesitations, (c) words per silent hesitation, (d) open class phrases, and (e) optional open phrases per speech sample, and a decrease in the number of modalizations and interjections. An increase in the number of filled hesitations occurring per minute, as well as a decrease in syntactic complexity separated moderate from mild Parkinson's patients. Our interpretation of the data favors the hypothesis that changes in the structure of spontaneous language production with increasing severity of dysarthria reflect PD patients' adaptation to their disease. <s> BIB001 </s> High-Level Language Production in Parkinson's Disease: A Review <s> Fluency Impairments. <s> Abstract An analysis of the temporal (prospective) form (silent and filled hesitations, repetitions, incomplete phrases, context-related comments, interjections), syntactic form, and lexical (retrospective) form (verbal deviations, open and closed class phrases) of spontaneous language production of early and middle stage Alzheimer's, Huntington's, and Parkinson's patients was made. Results showed that the language structure was disrupted in each disease, but in different ways. Temporal interruptions of varying types were frequent in the language of Alzheimer's and Huntington's Disease patients; only long-duration silent hesitations were frequent in Parkinson's language samples. Syntactic complexity was reduced in Huntington's Disease. Verbal paraphasias were found in both the language of Alzheimer's patients, as well as moderately advanced Huntington's patients. Closed class phrases were predominant in the language of Alzheimer's patients and Huntington's patients, and open class phrases in the language of Parkinson's patients. Taken together, the results suggest that (1) there is a unique neurolinguistic profile for spontaneous language production for each neurodegenerative disease, (2) pathology of the neostriatum disrupts syntactic organization, (3) adaptive strategies are used to cope with verbal and speech-motor difficulties, and (4) adaptive strategies fail to be effective with increasing disease severity. <s> BIB002 </s> High-Level Language Production in Parkinson's Disease: A Review <s> Fluency Impairments. <s> Young and older adults provided language samples in response to elicitation questions while concurrently performing different tasks including walking, , finger tapping, and ignoring speech or noise. The language samples were scored on three dimensions: fluency, grammatical complexity, and content. The hypothesis that working memory limitations affect speech production by older adults was tested by comparing language samples collected during a baseline condition with those produced while the participants were performing the concurrent tasks. There were baseline differences: older adults’ speech was less fluent and less complex than young adults’ speech. Young adults adopted a different strategy in response to the dual task demands than older adults; they reduced sentence length and grammatical complexity while performing the concurrent tasks. In contrast, older adults shifted to a reduced speech rate in the dual task conditions. <s> BIB003 </s> High-Level Language Production in Parkinson's Disease: A Review <s> Fluency Impairments. <s> Experimental studies of sentence production in Parkinson disease (PD) are rare. This study examined the relationship between cognitive abilities and performance on two sentence production tasks, sentence repetition, and sentence generation, in which complexity was manipulated. Thirty-eight older adults aged 60 to 85, half with PD, completed the two language tasks plus a cognitive battery. Participants with PD performed more poorly in the repetition task overall, especially in fluency, but differences were no longer significant once cognitive ability was controlled. In contrast, on the sentence generation task the PD group was significantly impaired on all language dimensions and overall performance. Although cognitive ability accounted for significant variance in all measures of sentence generation, the PD group remained significantly impaired when these factors were controlled. These findings suggest that, although language production is influenced by cognitive abilities, it can be significantly impaired in PD over and above the effects of differences in cognitive abilities. <s> BIB004
Determining the etiology of difficulties with fluency of language production in PD presents a complex problem due to the motor speech problems associated with the disease. Perhaps as a result of this potential confound, few researchers have examined fluency of language production in this population. The evidence from the three studies reported here that examined fluency BIB004 BIB002 BIB001 suggests that fluent production of speech is a major problem for individuals with PD. Furthermore, all three studies agree that the fluency problem is due to difficulties at more than one level of processing. Based on our analysis above that sentence repetition primarily taps positional processing and subsequent motor programming, articulation, and monitoring, our study BIB004 suggests that a good deal of the fluency difficulty in PD can be traced to these levels. However, the available research cannot distinguish fluency disruptions at the positional level from those at the motor planning or articulation levels. On the other hand, we found fluency was even more impaired in the sentence generation task than in repetition, which additionally requires message generation and functional level processing. This suggests that difficulties at the message level and/or functional level can also disrupt fluency although we cannot isolate the difficulty to one of these two levels. Additionally, we found that working memory and executive function predicted significant amounts of variance in fluency rates in repetition and sentence generation, but only in the latter task did the two groups differ in fluency when cognitive variables were controlled. In fact, group (PD versus healthy control subjects) accounted for more than 25% of the variance in fluency in sentence generation, but only 5% in repetition. This suggests that contrary to expectations, impaired fluency at earlier levels of language production (message and functional level) might be even more characteristic of PD than impaired fluency at later levels (positional processing, motor planning and articulation levels). Expanding upon the suggestion by Illes BIB002 , we hypothesize that fluency might be considered a measure of timing coordination within the language production system. If all stages of the language production process are working well and at a similar pace, then each element required for the intended sentence will be available when needed, and language production will be fluent. However, any variability in the timing of any essential component, (e.g., conceptual activation, lexical access, grammatical manipulation, sentence assembly, phonetic assembly, or motor planning) will potentially impair fluency. This hypothesis is consistent with findings that language production fluency is frequently impaired in dual task experiments  BIB003 which require coordination and planning of the timing of two tasks performed simultaneously, thus potentially interfering with timing (and accuracy of performance) in both. Studies looking at the effect of dual tasks on language production in PD are currently underway in our lab. One of the difficulties for future studies examining these issues will be distinguishing between disfluencies that are due to faulty timing, disfluencies that are to due to poor word choice to encode a message, and disfluencies due to self-monitoring. More research is certainly needed on ways to distinguish the etiology of fluency disruptions in PD and other populations.