Action naming is impaired in Parkinson disease patients.

In order to explore the possible contribution of the motor system to the representation of verbs, we studied the relative preservation of the capacity of Parkinson disease patients to name matched sets of object and action pictures. The performance of this group of participants was compared with that of a group of healthy seniors, and a group of Alzheimer disease patients. Generalized linear mixed-effects analyses showed that, whereas the two control groups had similar accuracy scores in response to objects and actions, Parkinson disease patients presented a significant impairment in their capacity to name actions compared to objects. The results of this study support the idea that verb representations are grounded in neural networks to which brain areas involved in motor control contribute.