Verbal fluency as a function of a measure of verbal intelligence and in relation to different types of cerebral pathology.

A measure of verbal fluency was derived from groups of patients with focal lesions and dementia and from normal control subjects. A regression equation was also derived to predict fluency from an index of verbal intelligence. Subjects with right or left frontal lesions and those with dementia had depressed fluency scores. When verbal intelligence was taken into account using the regression equation, fluency still remained depressed in subjects with frontal lesions, but for dements the obtained fluency score was similar to that predicted from the measure of verbal intelligence. The results suggest that impaired fluency is a specific phenomenon following frontal lesions but is merely a consequence of intellectual deterioration in dementia.