Action (verb naming) fluency as an executive function measure: convergent and divergent evidence of validity.

Numerous studies have demonstrated dissociable neuroanatomic underpinnings for the retrieval of grammatical classes of words such as nouns and verbs. Whereas retrieval of common and proper nouns is primarily mediated by posterior and anterior temporal regions, respectively, verb retrieval is primarily mediated by frontal regions. The majority of studies evaluating verb production have utilized tasks requiring subjects to name a graphically depicted action (i.e. action naming), leaving tests of verb generation in the absence of prompting stimuli (i.e. action fluency) largely unexamined. In a recent study, Piatt, Fields, Paolo, Koller and Tröster (in press) found that an action fluency task discriminated demented Parkinson's disease (PD) patients from non-demented PD patients and healthy control subjects, whereas lexical and categorical fluency tasks did not. These authors suggested that action fluency was sensitive to the fronto-striatal pathophysiology associated with PD dementia, and thus, that action fluency might serve as an indicator of executive functioning. This study was undertaken to evaluate the construct validity of action fluency as an executive function measure in a group of healthy elderly control subjects. Findings revealed modest to moderate relationships between action fluency and several putative executive measures. Action fluency was unrelated to indices of semantic and episodic memory. Results support the construct validity of action fluency as an executive function measure and suggest that this task may provide some unique information not tapped by traditional executive function tasks.