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We administered verbal (category naming, letter fluency) and nonverbal (category drawing, design fluency) tasks to patients with Parkinson's disease (PD). PD patients were significantly impaired only in their category naming for a semantic target like fruit. We tested the hypothesis that compromised lexical retrieval contributed to PD patients' impaired category naming by examining free recall and recognition on a supraspan learning task. PD patients were significantly impaired in free recall but not recognition. Category naming fluency correlated with free recall but not recognition on the supraspan learning task. We argue that the verbal fluency deficit in PD is due to a lexical retrieval impairment and that the difference between category naming and letter fluency is due to the nature of the prompts for lexical retrieval that patients can derive from these tasks.A verbal fluency deficit stands among the many subtle neuropsychological impairments occurring in nondemented patients with idiopathic Parkinson's disease (PD). Verbal fluency tasks are complex and involve several cognitive processes: (a) attention and vigilance to maintain a controlled and selective mental search of stored verbal information, (b) a lexical or semantic store to be searched, (c) a retrieval mechanism, and (d) a working memory device that keeps track of the items that have already been produced. The purpose of this study was to confirm the presence of the fluency deficit in PD patients and to begin determining the basis for this impairment.A number of studies have reported impaired category naming in nondemented PD patients (Beatty,

Sentence comprehension is a complex process involving at least a grammatical processor and a procedural component that supports language computations. One type of cerebral architecture that may underlie sentence processing is a network of distributed brain regions. We report two experiments designed to evaluate the cognitive and physiological substrate of sentence processing diaculties in nondemented patients with Parkinson's disease (PD). In the first experiment, patients answered simple questions about sentences that varied in their computational demands. Group and individual patient analyses indicated that PD patients are significantly compromised on this task, and that their difficulties become more prominent as the computational demands of the sentences increase. We manipulated the set of sentences to stress performance aspects of sentence processing. PD patients were compromised in their ability to detect errors in the presence and nature of a sentence's grammatical morphemes, suggesting a deficit in selective attention, but their ability to answer questions about a sentence was not afFected by short-term memory factors. In the second experiment, positron emission tomography was used to correlate this pattern of sentence comprehension impairment with regional cerebral glucose metabolism (rCMRgl) obtained at rest in a representative subset of these PD patients. Grammatical comprehension and attention in sentence processing correlated significantly with mesial frontal rCMRgl. Regression analyses confirmed the central role of left mesial frontal cortex, and identified a subsidiary role for left caudate in overall sentence comprehension, for left dorsolateral frontal cortex in grammatical processing, and for bilateral dorsolateral frontal cortex in attending to the presence of grammatical features. We conclude that compromised mesial frontal functioning underlies in part the sentence processing deficit of these patients, and these data illustrate one method for mapping portions of a sentence processing mechanism onto a distributed cerebral architecture.

We asked 24 nondemented Parkinson's disease (PD) patients to copy and then recall the Rey-Osterrieth Complex Figure, dividing the units of the figure into "main structural" and "detail" components. PD patients persistently omitted some main structural units from their recall of the figure. When main structures were produced, PD patients were impaired at drawing these features in an organized fashion, and they produced these main units late in the course of their drawings. PD patients differed from control Ss in their recall of the figure's details, but there were no qualitatively unique features in their omission of details. Correlation and regression analyses suggest that compromised executive functioning contributed to the PD patients' constructional difficulties and that visual perception and motor functioning also played a modest role. We conclude that visual construction impairments in PD are multifactorial in nature.

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.