Sentence comprehension and praxis deficits in Parkinson's disease.

We evaluated the ability of nondemented patients with idiopathic Parkinson's disease (PD) to interpret various aspects of sentences and to perform learned limb and oral gestures. The patients were significantly compromised in their ability to answer simple questions about sentences such as "The eagle chased the hawk that was fast. Which bird was chased?" A discriminant analysis revealed that up to 73% of PD patients differ from control subjects in their ability to perform this task. Patients with PD were also significantly compromised in their gestural performance, and a discriminant analysis indicated that a praxis deficit may be evident in up to 64% of patients. We conclude that language and gestural processing impairments are frequent in patients with PD.