Exploring Sentence Production in Parkinson's Disease: Effects of Conceptual and Task Complexity

Michelle S. Troche1,3, Lori J.P. Altmann1, 3, John C. Rosenbek2,3, & Christine M. Sapienza1,3

1Department of Communication Sciences and Disorders; 2Department of Communicative Disorders, University of Florida 3 VA RR & D Brain Rehabilitation Research Center, Malcom Randall VAMC, Gainesville, Florida

METHODSParticipants:• 20 non-demented persons with PD

- Average Schwab & England Score: 63% (0.20); Hoehn & Yahr Stages II-III• 15 age-matched Healthy Older Adults (HOA)• Groups similar in age (PD 70.5, HOA 71.4, p > .7)• Groups different in DRS (PD 136.4, HOA 140.3; t(32) = 2.04, p = .05)

Neuropsychological measures:• Digit span forward (max 14; PD 8.8, HOA 8.3, p > .4)• Digits span backward (max 14; PD 6.6, HOA 6.9, p > .6)• Digit ordering (max 24; PD 14.3, HOA 16.6, p < .08)• Trails A (secs.; PD 124.9, HOA 106.5; p > .4)• Trails B (secs.; PD 209.0, HOA 154.1, p > .15)• Stroop XXX (number in 45s; PD 59.9, HOA 64.9, p > .3)• Stroop color words (PD 27.3, HOA 33.8, p < .08)

Sentence Generation/Picture Description Task (see examples below): • Stimuli including 40 line drawings depicting a variety of common events were

presented offline. Pictures are from Kempler (8) and Bock (9) • Designed to elicit 2 sentence types varying in complexity

Sentence Repetition Task (7): The sentence repetition task included 30 sentences of the two target grammatical

complexities. Sentences were matched for number of syllables and words, word frequency, and semantic density (i.e., number of propositions) (7).

***********************************************************************************************Dependent Variables: All responses were digitally recorded, transcribed verbatim, and

scored on four error dimensionsCompleteness (mentions all actors & an appropriate action)Fluency (sentence produced without pauses, ums/uhs, false starts or restarts) Grammaticality (sentence is grammatical)Gist meaning (captures overall idea of the picture, may use pronouns)

INTRODUCTIONThe expressive language abilities of people with Parkinson’s disease (PD) have not been well described in the literature, but include impaired word fluency, especially in verbal fluency (1) and confrontation naming tasks (2). Likewise, in higher level language there are reports of a reduction in the amount of information content (3) and the use of simplified grammar in spontaneous language production relative to healthy older adults (4). These effects may be due to deficits in executive function in individuals with PD.

Sentence production is a complex task that taxes linguistic and cognitive resources, particularly executive function and working memory resources. Repeating a sentence requires verbatim recall of words and sentence structure. The generation of novel sentences is more resource intensive, requiring the generation of an idea, lexical retrieval, and syntactic planning, which are not necessary in a repetition task. Current research shows that the conceptualization and encoding of grammatical complexity for a novel sentence tax the working memory system (5,6).

It is known that persons with PD exhibit deficits in executive function and working memory (1). Therefore, we predicted that, compared to healthy older adults (HOA), individuals with Parkinson Disease (PD) would demonstrate deficits in sentence production due to impaired executive function. We also predicted that increasing the grammatical and task complexity would interfere with the quality of the sentences produced. We did not expect Group to account for additional variance when executive function was accounted for.

CONCLUSIONSRESULTS

Acknowledgements: We would like to thank Dan Kempler and Kay Bock for sharing their picture stimuli with us. Many thanks to Lauren Hudson and Kelsey Wallace for their help with data acquisition and analysis. This study was supported in part by VA Office of Research and Development, Rehabilitation R&D Service, Brain Rehabilitation Research Center and by the MJ Fox Foundation. The presenters have no conflicts of interest.

For questions or comments: Michelle S. Troche – michi81@ufl.edu

Simple (one or two actors): The man is kissing the woman

Complex (three actors):The cat that the boy is catching is scratching

the dog.

• Participants with PD performed more poorly than Controls. Main effect of Group (p = .002)

• Significant main effect of Error Type (p=.000); dysfluent > ungrammatical > complete = gist.

• Error type interacted with group (p<.001)-Both groups were equally good at reproducing gist meaning; but, PD participants produced significantly fewer complete, fluent, and grammatical responses. -There were no other significant group interactions

• Significant main effect of complexity (p=.002) -Using more complex grammatical/ conceptual structures resulted in greater language breakdown.

Language deficits in PD have been rarely reported. • We found PD has pervasive effects on language use.• All language production dimensions were affected. • Although performance on the repetition task was significantly better than performance on the generation task, this was only a relative strength

• the mean percent of sentences repeated correctly < 50%.• Preservation of gist meaning relative to more impaired ‘completeness’

• reflects the presence of synonyms, pronouns, semantic paraphasias, and simplified or altered grammatical structures in both tasks.

• Difficulties with language production were exacerbated by the complexity of language targeted and by the task (i.e. repetition vs. picture description).

- Thus, more complex language tasks are needed to reveal this deficit, which may be masked when only single-word tasks are used, as is standard practice now.

We hypothesized that executive function deficits would contribute to language production difficulties in PD.

• This is supported by the strong effects of task and complexity (captured here by requiring the inclusion of three actors and two actions in a single sentence)

• The regression analyses support this to some extent• Executive function accounted for significant portions of the variance in the abilities to encode gist meaning of a sentence, to repeat a sentence verbatim, and

to give a complete description of a picture.• Executive measures also contributed to the total number of sentences repeated

completely correctly.

PD-severity contributed to all sentence generation measures in the picture description task even though the severity rating is based on physical impairment and independence.

• The language generation task is highly resource dependent and requires activation of the concept, the linguistic code, and the motor plan/program.

• PD-severity is measured by performance of activities of daily living, which is likely highly dependent upon the relationship between cognitive-linguistic and motor systems

• Initiating, organizing and maintaining thought processes for language production and accomplishing activities of daily living likely call on similar cortical and subcortical regions of the brain as motor activity.

• Thus, damage due to PD may impair generation of both motor and linguistic activity

• In addition to severity, diagnosis of PD unexpectedly contributed independently to fluency of production and overall ability to generate adequate sentences in the picture description task.

• PD affects some aspects of language generation even more than would be expected based on severity alone.

• These phenomena require significant investigation• Our lab is currently investigating the interactions among cognition, motor-speech,

and language production in PD.

Difficulties with language production fluency, grammaticality and encoding a complete message can significantly affect everyday interactions and quality of life.

• In particular, difficulty with effective communication of complex ideas may hamper the ability of individuals with PD to discuss and contribute to decision making about complex topics, such as end of life issues and financial planning.

• This issue also deserves further study.

What are the contributions of PD severity, age, executive function to sentence production?

After these are accounted for, does Group account for additional variance?

Hierarchical stepwise regression model. 1st step: Schwab & England (PD-severity) stepwise; 2nd step: age and neuropsychological variables entered stepwise; 3rd step: Group stepwise.

For the Repetition Task:

Gist responses: Trails B accounted for 42% of the variance

Complete responses: Trails B accounted for 28% of the variance

Fluent responses: PD-severity (.214), and DSF (.14) accounted for 35% of the variance

Grammatical responses: Trails B accounted for 15.5% of the variance

Total good responses: PD-severity (.186) and Stroop Xs (.178) accounted for 36% of the variance

For the Sentence Generation Task:

Gist responses: PD-severity (.23) and Trails A (.21) accounted for 44% of the variance

Complete responses: PD-severity (.33) and Trails A (.23) accounted for 56% variance

Fluent responses: PD-severity (.37) and Group (.10) accounted for 47% of the variance

Grammatical responses: PD-severity accounted for 16.5% of the variance

Total good responses: PD-severity (.443) and Group (.08) accounted for 53% of the variance

EXECUTIVE FUNCTION AND LANGUAGE PRODUCTION

Simple: The passenger from the suburbs waited for the train.

Complex: The job that the woman wanted required a college education.

• Significant interactions were found between task and error type (p=.000) - Gist did not differ between tasks - Completeness was better in the Generation task - Fluency and grammaticality were better in Repetition

• A significant three-way interaction was found between task, error type and complexity (p=.033) - Effects of complexity were generally greater in the generation than the repetition task. - Fluency and grammaticality were more sensitive to complexity in the sentence generation task - Completeness and gist were more sensitive to complexity effects in the repetition task

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REFERENCES

1. Huber, S.J., Shuttleworth, E.C., & Paulson, G.W. (1986). Dementia in Parkinson’s disease. Archives of Neurology, 42, 987-990. 2. Globus, M., Mildword, B., & Melamed, E. (1985). Cerebral flow and cognitive impairment in Parkinson’s disease. Neurology, 35, 1135-1139. 3. Cummings, J.L., Darkins, A., Mendez, M., Hill, M.A., & Benson, D.F. (1988). Alzheimer’s disease and Parkinson’s Disease: Comparison of speech and

language alterations. Neurology, 38, 680-684.4. Murray, L.L. (2000). Spoken language production in Huntington's and Parkinson's diseases. Journal of Speech, Language, and Hearing Research, 43,

1350- 1366.5. Kemper, S., Herman, R.E., & Liu, C. J. (2004). Sentence production by younger and older adults in controlled contexts. Journals of Gerontology:

Psychological Sciences, 58B, P220-P224.6. Kemper, S., Herman, R., & Lian, C. (2003). Age differences in sentence production. The Journals of Gerontology: Series B, Psychological Sciences and

Social Sciences, 58, P260-268. 7. Small, J.A., Kemper, S., & Lyons, K. (2000). Sentence repetition and processing resources in Alzheimer’s disease. Brain and Language, 75, 232-258. 8. Kempler, D. (2003). Kempler Comprehension Test. Unpublished ms.9. Bock, K., Loebell, H. & Morey, R. (1992). From conceptual roles to structural relations: Bridging the syntactic cleft. Psychological Review. 99(1), 150-171.

SCHWAB & ENGLAND Scale for Activities of Daily Living for People with Parkinson’s Disease Scoring: 5 questions, each rated on a 5-point likert scale, which is then transformed into a percentage score.

Dependence Abilities Awareness Percent

none; completely independent can do all chores without slowness, difficulty or impairment; normal

unaware of any difficulties 100%

none can do all chores but with some degree of slowness, difficulty or impairment

beginning to be aware of difficulty 90%

none takes twice as long to do chores conscious of difficulty and slowness 80%

none more difficulty with some chores; takes 3-4 times as long   70%

some dependency can do most chores but very slowly and with much effort; makes errors

some impossible 60%

more dependent slow and needs help has difficulty with everything 50%

very dependent can assist with all chores but can only do a few alone   40%

part invalid much help needed; may be able to do a few alone with much effort

  30%

severe invalid can do nothing alone; may be able to help a little in some tasks   20%

totally dependent; complete invalid helpless   10%

Schwab RS, England AC Jr. Projection techniques for evaluating surgery in Parkinson's Disease. pages 152-157 (Table 1, page 153). IN: Third Symposium on Parkinson's Disease, Royal College of Surgeons in Edinburgh, May 20-22, 1968. E. & S. Livingstone Ltd. 1969.