Parkinson’s disease (PD) is associated with an action language deficit. Subthalamic nucleus deep brain stimulation (STN DBS) deteriorates verbal fluency, but may improve verb naming more than nouns in PD. We investigated effects of grammatical class (verb vs noun), action content (action vs non-action) of words and unilateral, bilateral or no stimulation on naming. Nouns were named more accurately and faster by controls and PD participants; however the noun-verb difference was higher for PD participants. Language, executive and visuospatial function deficits in PD accounted for this difference between PD group and controls. Noun-verb difference was accounted by differences in imageability, familiarity and complexity of the stimuli. Non-action words were named more accurately than action words in the overall sample. Stimulation conditions did not have an effect on naming. This study in Turkish-speaking participants show an action language deficit due to underlying cognitive deficits without an STN DBS effect in PD.
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