Verbal fluency deficits in patients with schizophrenia: Semantic fluency is differentially impaired as compared with phonologic fluency

Patients with schizophrenia show deficits in phonologic (ability to name words that begin with a specific letter, e.g., F) and semantic (ability to name members of a category, e.g., ''animals'') fluency. Whereas the former deficit has been presumed to reflect a dysfunction of the frontal lobe, the latter has been linked to frontal and temporoparietal brain areas. These 2 verbal fluency measures were studied in a sample of 27 schizophrenia patients and 24 normal controls who were matched on age and a putative measure of premorbid intellectual ability. A 2-min production task of switching between letters and between categories measured demand for flexibility. On switching and nonswitching tasks controls produced more words during semantic versus phonologic fluency. Conversely, schizophrenia patients produced more words for letters than for categories, suggesting dysfunction of the frontal and temporoparietal areas of the brain. Furthermore, the greater impairment of semantic fluency may be related to a breakdown of semantic information processing beyond ''executive'' search and retrieval.