Quantitative analysis of language production in Parkinson’s disease using a cued sentence generation task SARAH VANHOUTTE 1 , MIET DE LETTER 2 , PAUL CORTHALS 2 , JOHN VAN BORSEL 2,3 & PATRICK SANTENS 1 1 Department of Neurology, Ghent University Hospital, Ghent, Belgium, 2 Department of Oto-Rhino- Laryngology and Logopaedic/Audiologic Sciences, Ghent University Hospital, Ghent, Belgium, and 3 Veiga de Almeida University, Mestrado em Fonoaudiologia, Rio de Janeiro, Brazil (Received 17 November 2011; revised 25 June 2012; accepted 09 July 2012) Abstract The present study examined language production skills in Parkinson’ s disease (PD) patients. A unique cued sen- tence generation task was created in order to reduce demands on memory and attention. Differences in sentence production abilities according to disease severity and cognitive impairments were assessed. Language samples were obtained from 20 PD patients and 20 healthy control participants matched for age, sex and educational level. In addition, a cognitive test for verbal memory and resistance to cognitive interference was administered. Statistical comparisons revealed significant language changes in an advanced stage of the disease. Advanced PD patients showed a reduction in lexical diversity in notional verbs, which was absent in nouns. Cognitive dysfunctions such as impaired verbal memory are suggested to contribute to the typical noun/verb dissociation in PD patients. In addition, advanced PD patients produced more semantic perseverations, which may be related to set-switching problems. In conclusion, whether language disturbances in PD are the result of non-linguistic cognitive dysfunctions or reflect pure language deficits exacerbated by cognitive impairments, remains a matter of debate. However, the negative impact of cognitive dysfunctions may be important. Keywords: Parkinson’ s disease, language, language analysis, cognition, language production, executive functions Introduction Parkinson’ s disease (PD) is a progressive, neurodegenerative disorder with an estimated prevalence of around 3/1000 in the general population and 1/100 in individuals over 60 years (de Rijk et al., 1995; Morgante et al., 1992; Samii, Nutt, & Ransom, 2004). In PD, neurodegeneration in the substantia nigra causes dopamine depletion in the striatum which disrupts basal ganglia–thalamocor- tical circuits (Alexander, DeLong, & Strick, 1986). Although PD is traditionally viewed as a motor disease, non-motor and cognitive symptoms may occur as well (Alves, Forsaa, Pedersen, Gjerstad, & Larson, 2008; Caballol, Marti, & Tolosa, 2007; Gelb, Oliver, & Gilman, 1999; Jankovic, 2008; Pio- vezan, Teive, Piovesan, Mader, & Werneck, 2007; Ziemssen & Reichmann, 2007). Communication Correspondence: Miet De Letter, Department of Oto-Rhino-Laryngology and Logopaedic/Audiologic Sciences, Ghent University Hospital, UZ Ghent 2P1, De Pintelaan 185, B-9000 Ghent, Belgium. Tel: +32 9 332 53 64. Fax: +32 9 332 49 93. E-mail: miet.deletter@ugent.be Clinical Linguistics & Phonetics, October 2012; 26(10): 863–881 © 2012 Informa UK Ltd ISSN: 0269-9206 print / ISSN 1464-5076 online DOI: 10.3109/02699206.2012.711420