Preliminary evidence for impaired rapid verb generation in schizophrenia☆

Abstract

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)...

Action and object naming in schizophrenia

“…Furthermore, there was no significant difference retrieving the semantically more complex verbs (e.g., instrumental since an instrument is part of the verb) for this group of schizophrenic patients. This noun superiority over verbs supports previous findings of specific action word retrieval problems in individuals with SCZ on verb fluency tasks (Marvel et al, 2004;Woods et al, 2007).…”

“…Overall, schizophrenic patients showed significantly poorer naming than controls on all measures of object and action lexical semantic access and retrieval despite normal comprehension for action and object names. This robust finding supports the notion that lexical semantics is a generalized deficit in schizophrenia (Leeson et al, 2006) and that both action and object name retrieval can be similarly impaired (Woods et al, 2007). Furthermore, the result is in line with findings from studies that have examined visual confrontation naming abilities of schizophrenic individuals compared to controls on object picture naming tasks (Barr et al, 1989;Gabrovska et al, 2003;Laws et al, 2000;Leeson et al, 2006;Leeson et al, 2005) including the Boston Naming Test (Barr et al, 1989;Berenbaum et al, 2008;Vogel et al, 2009).…”

“…It is possible that due to the simultaneous activation of more than one lemma for the target action word, selecting the single, correct target verb was difficult for the SCZ participants. This follows on from reports that individuals with SCZ have difficulties strategically searching and selecting a word from the lexicon from among many competitors (Elvevag et al, 2001), and action names in particular are vulnerable (Marvel et al, 2004;Woods et al, 2007).…”

“…In contrast, nonsemantic or otherwise lexical access impairments in SCZ can include difficulties accessing the target response from among several competing sources of information or problems with strategic search and retrieval (Elvevag, Weinstock, Akil, Kleinman, & Goldberg, 2001). Further, nonlinguistic processes may be impaired in SCZ such as working memory and attention (Braff, 1993;Gold, Carpenter, Randolph, Goldberg, & Weinberger, 1997 Word retrieval breakdown in schizophrenia has been assessed using a variety of tasks including tests of semantic association (Bozikas et al, 2005) and word generation, including category-based (Bokat & Goldberg, 2003;Kubota et al, 2005), letter-based (Berenbaum et al, 2008;Kubota et al, 2005;Woods, Weinborn, Posada, & O'Grady, 2007) verb (action;Marvel, Schwartz, & Isaacs, 2004;Woods et al, 2007), noun (animal;Berenbaum et al, 2008;Woods et al, 2007) fluency tasks and object picture naming tasks (Barr, Bilder, Goldberg, Kaplan, & Mukherjee, 1989;Berenbaum et al, 2008;Laws et al, 2000;Leeson et al, 2006;Leeson, McKenna, & Laws, 2005;Vogel et al, 2009).…”

“…Two studies have been found that investigate action word retrieval using a verbal fluency task (Marvel et al, 2004;Woods et al, 2007) Specifically, Marvel et al asked individuals with SCZ to read an object name and produce an action word that described what the object does or what one can do with the object-that is, respond with a semantically related action word (e.g., read the word "pill" and say "swallow"). Individuals with SCZ had significant difficulties retrieving the correct target verb for nouns with many possible verb responses, in contrast to healthy controls (e.g., ball: "bounce," "throw," "hit").…”