Action and object naming in Parkinson's disease without dementia.

The present study aimed to assess the ability in objects and actions naming in Parkinson's disease (PD) patients. Further, we wished to assess the effect of a particular conceptual dimension, i.e. manipulability, on the naming of object and actions. Patients were recruited from the Department of Neurology, University of Brescia. Thirty-two were diagnosed as PD, according to published criteria, and 15 healthy volunteers matched in age and education to patients' sample. All patients underwent a detailed clinical and neurological evaluation. The stimuli used in the action-object picture naming task were taken from the Center for Research in Language-International Picture Naming Project corpus. To assess the effect of manipulability (or the involvement of fine hand movements) the noun-verb stimuli were re-categorized into manipulable and non-manipulable items (i.e. objects which can or cannot be manipulated and actions which do or do not involve fine hand movements). Patients showed a deficit both in action and object naming, compared with controls. In addition, patients with PD but not controls were significantly more impaired in action than in object naming. The current study supports the view that action naming is affected in patients with PD, possibly reflecting the presence of prefrontal dysfunction.