It has been hypothesized that nouns and verbs are processed within relatively separable semantic memory networks. Although abnormal semantic processing is a common feature of schizophreniaspectrum disorders, no prior studies have specifically examined the comparability of noun and verb generation deficits in schizophrenia. In the current study, verb (action), noun (animal), and letter (f) fluency performance was evaluated in 22 inpatients with schizophrenia and 27 healthy comparison subjects. On average, individuals with schizophrenia performed approximately one standard deviation below the healthy comparison subjects on action, animal, and letter fluency. Action fluency -but not letter or animal fluency -was moderately correlated with tests of working memory, response inhibition, semantic memory, and cognitive flexibility. Findings suggest that verb-and noun-based fluency deficits are of comparable severity in schizophrenia, but that the impairment in verb generation may be driven by different underlying cognitive mechanisms. Further, hypothesis-driven research on the nature and extent of verb network disruption in schizophrenia appears warranted.
KeywordsSchizophrenia; Neuropsychology; Cognitive processes; Verbal fluency; Verbs Abnormalities within frontotemporal systems are hypothesized to play an important role in the etiology and expression of schizophrenia-spectrum disorders (SCZ). For example, in addition to ventriculomegaly, neuroimaging studies reveal altered structure and function of the thalamus, medial temporal lobes, and prefrontal cortex in individuals with SCZ (Davidson & Henrichs, 2003;Shenton, Dickey, Frumin, & McCarley, 2001). SCZ is also associated with impairments in many aspects of cognition, most notably episodic memory, language, attention, working memory, and executive functions (e.g., Fioravanti, Carlone, Vitale, Cinti, & Clare, 2005). Another common feature of SCZ is impairment in semantic memory, which is an aspect of declarative memory in which information related to facts, symbols, and concepts are * Address correspondence and reprint requests to: Steven Paul Woods, Psy.D., Department of Psychiatry (0847), University of California, San Diego, 150 West Washington Street, 2 nd floor, San Diego, CA, USA 92103. Electronic mail may be sent to spwoods@ucsd.edu. Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. processed (e.g., McKay, McKenna, Bentham, Mortimer, Holbery, & Hodges, 1996). It has been argued that the thought disorder evident in some individuals with SCZ, which is often expressed as disorganized speech (e.g., loose associations)...