Sequential production of motor-action verb subtypes in Parkinson's disease patients

Motor-action verbs (MAVs) production and comprehension are compromised in patients with Parkinson's disease (PD). OBJECTIVES: The aim of this study was to characterize the sequential production of three subtypes of MAVs in PD patients: whole body (e.g., run), specific body part (e.g., kick), and instrumental (e.g., saw). This study also aimed to identify the production characteristics for each of the two main phases in fluency performance: selection (initial abundant item production) and retrieval (more paced and scarce production). METHODS: This study involved a group of 20 nondemented, on-medication PD patients, with an average age of 66.59 years (standard deviation = 4.13), and a comparison group (CG) of 20 normal elderly individuals, matched by years of education and controlled for cognitive performance and depression. Both groups performed a classical verb fluency task. Sequential word-by-word analyses were conducted. RESULTS: Significant differences were found at the initial production of whole-body MAVs and the overall production of instrumental verbs (both measures were lower in the PD group). A repeated-measures analysis of variance confirmed the linear CG performance and the quadratic PD performance. CONCLUSIONS: PD patients present altered production of whole-body and instrumental MAVs. This proposal for the semantic sequential analysis of motor verbs deserves further investigation, as a new methodology for the evaluation of fluency performance in motor-related disease.