Speaking Population with Parkinson. Disease. Karim Johari1 & Hassan Ashayeri2. 1Department of Speech and Language Pathology, Faculty of Rehabilitation,.
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The Grammatical Deficit in Regular Past Tense Formation: A Study of Persian Speaking Population with Parkinson Disease Karim Johari1 & Hassan Ashayeri2 of Speech and Language Pathology, Faculty of Rehabilitation, Tabriz University of Medical Science, Tabriz (Iran) 2 Department of Rehabilitation Science, Faculty of Rehabilitation Science, Tehran University of Medical Science, Tehran (Iran)
1 Department
Introduction Parkinson’s disease impairs motor and cognitive functions from the initial stages of the Disease (Owen et al., 1992). These patients have problems in executive functions and language. With respect to the language component, syntax, morphology and phonology aspects display more deficits than semantic aspects. This may be the result of cortical - subcortical language networks dysfunctions which support these three language levels. PD patients have more problems in regular morphology, which is processed implicitly in comparison to irregular morphology, which is more explicitly represented. Neurolinguistic studies of past tense formation in patients with subcortical dysfunction result in the declarative/procedural model of language processing which in regular behavior (regular morphology) is subserved by implicit memory that recruits corticosubcortical networks whereas the temoroparietal cortex is involved in irregular behavior processing (semantic knowledge and irregular morphology) (Ullman, 2004). Several neurolinguistic studies have investigated the DP model for regular and irregular verbs in PD patients. Ullman et al. (1997) studied the past regular and irregular verbs production in PD. They found out that regular verbs were impaired in PD but irregular verbs exhibited less deficits. The DP model has been studied in several different populations with PD (English, French and Greek). Investigations in French and English showed greater impairment in regular verbs as compared with irregular verbs (Terzi, Papapetropoulos, & Kouvelas, 2005). In contrast Greek patients with PD did not have significant differences between regular and irregular verbs. One of the limitations in DP model studies is that they have not been done in many languages. Another drawback is that there are no studies that have assessed cognitive impairments and their effects on patient’s syntactic behaviors. The aim of the present study was to investigate past tense formation in a new population of patients with Parkinson’s disease, namely speakers of Farsi. Furthermore the effects of the participants’ cognitive status on regular and
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irregular production will be assessed. Farsi is an Indo-European language, belonging to the Iranian branch of the Indo-Iranian group. Typologically, it is a SOV language with a rather rich morphology. There is no gender agreement in Farsi but there is subject-verb agreement with respect to person and number. Each verb has a past stem and a present stem. The past regular verbs are made by adding /id/ and /d/ to present stem before person agreement. Past irregular verbs are not rule-governed and the stem of verbs in present tense is not preserved in the stem of the past tense verb (Nilipour & Raghibdoust, 2001).
Method 20 right-handed patients with PD and 20 healthy subjects participated in the present study. The control group was matched for age, education and MMSE Scores. Besides the MMSE test, PD patients also received some neuropsychological tests to assess executive functions and visuospatial problem-solving skills (Wisconsin Card Sorting Test - WCST (Kongs, Thompson, Iverson, & Heaton, 2000), and Coloured Raven Progressive Matrices (Raven, 1965), respectively). The past tense formation task used was a sentence completion production task. Subjects were given 20 sentences. After each sentence was read to them it was repeated in the context of past eventbut except the verb’s place in the sentence was left empty. Subjects were asked to fill in the slot with the verb in the past tense. 20 of the verbs used have a regular past tense and 20 have an irregular past tense.
Results PD patients showed greater impairment in regular verbs with respect to irregular verbs, t(19)=2.4 , p=0.023. By contrast healthy controls performed equally between irregular and regular verbs t(29)=0.8, P=0.4. We analyzed the scores of Parkinson’s patients and healthy controls on each type of verb. Patients with Parkinson’s disease scored significantly lower than healthy controls for regular verbs t(48)=3.2,P=0.002, while no difference was found on irregular verbs between groups t(48)=0.54 , P=0.59 No correlations were found between the performances of patients with Parkinson’s disease on past tense formation tasks and neuropsychological tests either in regular or irregular verbs. The same holds true for healthy controls when their performance on past tense formation tasks was compared with their scores on the MMSE.
Discussion We studied past tense formation in Farsi speaking with Parkinson Diseases. Our result showed that PD patients had more impairment in the regular verb
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production whereas the irregular verbs were relatively intact. The output of the present study supports the DP model for regular Past tense formation. However, we could not find any relationship between past tense formation and cognitive status. This finding supports the claim of a linguistic deficits in PD, which cannot be attributed to the cognitive status. According to the Corollary of Murphy’s Law: only that which can go wrong will go wrong. In other words, the structure of the language determines what types of errors may occur (Paradis, 2001). For example there are no irregular verbs in Azari but they are frequent in Farsi (Johari et al.). Crosslinguistically, in some languages such as English there are clear-cut disassociation between regular and irregular verbs, however, there are no clear-cut disassociation between regular and irregular verbs in some languages such as Greek (Terzi et al., 2005). However there are several factors that are related to PD patients’ language impairments, which need to be considered in the discussion. The role of cognitive functioning is one of them. Studying PD patients with different stages of cognitive impairments may disclose the relationship between cognitive deficits and syntactic problems. In the present study we assessed PD patients with some neuropsychological tests and found that there was no statistically significant relationship between verb production and cognitive status. Investigation of effects of cognitive deficits on past tense formation with wide neuropsychology tests is recommended for future research in this field of study.
References Johari, K., Ashrafi, F., Zali, A., Ashayeri, H., Fabbro, F., & Zanini, S. Grammatical deficits in bilingual Azari - Farsi patients with Parkinson’s disease. Journal of Neurolinguistics(0). Kongs, S., Thompson, L., Iverson, G., & Heaton, R. (2000). WCST-64: Wisconsin Card Sorting Test-64 card version. Lutz, FL: Psychology Assessment Resources. Nilipour, R., & Raghibdoust, S. (2001). Manifestations of aphasia in Persian. Journal of Neurolinguistics, 14(2-4), 209-230. Owen, A., James, M., Leigh, P., Summers, B., Marsden, C., Quinn, N., et al. (1992). Fronto-striatal cognitive deficits at different stages of Parkinson’s disease. Brain, 115(6) 1727. Paradis, M. 2001). Manifestations of aphasia symptoms in different languages. Pergamon. Raven, J. (1965). Guide to using the Coloured Progressive Matrices Sets A. Ab, and BHK Lewis, London. Terzi, A., Papapetropoulos, S., & Kouvelas, E. D. (2005). Past tense formation and comprehension of passive sentences in Parkinson’s disease: Evidence from Greek. Brain and Language, 94(3), 297-303. Ullman, M. T. (2004). Contributions of memory circuits to language: The declarative/procedural model. Cognition, 92(1-2), 231-270.
