Lexical, semantic, and action verbal fluency in Parkinson's disease with and without dementia.

Previous research suggests that lexical and semantic verbal fluency are differentially sensitive to the effects of cortical and subcortical dementias, but little is known about action fluency performance in dementias. The present study compared lexical, semantic, and action fluency in groups of patients with Parkinson's disease (PD) with and without dementia and an elderly control group. Findings revealed an interaction between fluency type and subject group. Although the demented PD (PDD) group performed significantly more poorly than their non-demented counterparts and normal controls on all three fluency tasks, a disproportionate disparity in scores was noted on the action fluency task. The findings suggest that action fluency may be particularly sensitive to PD-associated dementia and may be an early indicator of the conversion from PD to PDD. As reported elsewhere, PD without dementia was not associated with significant impairment on any of the fluency tasks.