Verbal fluency deficits in Parkinson's disease.

Abstract

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,

Pattern of Executive Impairment in Mild to Moderate Parkinson's Disease

“…However, the research evidence is not consistent with regard to the reported level of impairment. There have been varying reports of performance on verbal fluency, a task commonly employed to estimate abilities related to frontal lobe function, with some studies reporting impaired performance [16,18,20,21], and other studies reporting no difference between PwPD and controls [14,22,23,24]. The verbal fluency task has been variously reported to measure EF, set-shifting, planning, language ability, or global cognition [21,22,25].…”

Language Processing in Parkinson's Disease Patients Without Dementia

“…The exact underlying nature of the semantic deficits has yet to be determined. Interestingly, Auriacombe et al (1993) examined the traditional semantic and phonemic fluency tasks, but also examined fluency performance in the non-verbal modality (i.e., design fluency and category drawing task). They found that PD patients' performance on the non-verbal fluency task was comparable to healthy speakers, and confirmed the discrepancy between relatively intact phonemic fluency and impaired semantic fluency.…”

“…It is not necessary to retrieve a word form during category drawing, since knowledge of the concept underlying a target superordinate (i.e., vegetable) and the exemplars that contribute to a superordinate is sufficient. To check the hypothesis that PD patients are impaired in the retrieval of semantic information, Auriacombe et al (1993) also administered a supraspan verbal learning task. A large proportion of the PD patients showed difficulties with free recall, but these patients were accurate at recognition, which is consistent with a retrieval deficit, and not an impairment of semantic memory itself.…”

Semantic profiles in mild cognitive impairment associated with Alzheimer?s and Parkinson?s diseases

“…Patients with Parkinson's disease (PD) frequently show a cognitive deterioration characterized primarily by a dysexecutive syndrome due to the pathological involvement of the frontal and prefrontal cortices and basal ganglia (Verbaan et al, 2007). Different hypotheses have been advanced to account for the semantic impairment found in these patients: a deficiency of semantic representation activation due to storage impairment, a dysfunction in semantic retrieval processes or increased spreading activation in lexical-semantic networks (Raskin et al, 1992;Auriacombe et al, 1993;Watters and Patel, 1999;Foster et al, 2008). A publication investigating cognitive functions in AD and PD patients with dementia (Song et al, 2008) found (with the exception of episodic memory) a similar neuropsychological pattern: both groups of patients showed the same difficulty in the task evaluating semantic knowledge.…”