Semantic Dysfunction in Women With Schizotypal Personality Disorder

Abstract

Objective-This study examined whether early or late processes in semantic networks were abnormal in women with a diagnosis of schizotypal personality disorder. The N400 component of the EEG event-related potentials was used as a probe of semantic processes.Method-Word pairs were presented with short and long stimulus-onset asynchronies to investigate, respectively, early and late semantic processes in 16 women with schizotypal personality disorder and 15 normal female comparison subjects. Event-related potentials were recorded in response to the last words in a pair.Results-With the short stimulus-onset asynchrony, the N400 amplitude was less negative in the schizotypal personality disorder group than in the normal comparison group. No group differences were found with the long stimulus-onset asynchrony.Conclusions-The finding of a less negative than normal N400 amplitude with the short stimulusonset asynchrony in women with schizotypal personality disorder supports the hypothesis that persons with this disorder evince an overactivation of semantic networks. The absence of group differences with the long stimulus-onset asynchrony, which is primarily sensitive to processes involved in context integration, suggests that in this group of schizotypal personality disorder subjects, additional demands on working memory may be necessary to bring out the semantic dysfunction.Language dysfunction in schizophrenia has been regarded a cardinal symptom of this disorder for almost a century (1). Clinical reports abound with examples of speech samples characterized by loose associations, lack of sensitivity to context, defective use of pronouns (2-4), or the inability to carry on a conversation bound by a theme (5). More recently, it has been proposed that language abnormalities in schizophrenia are mediated by dysfunctional processes in semantic memory. Specifically, it has been suggested that processes of activation and/or context utilization may be abnormal.Although several studies have investigated semantic processes in schizophrenia, few studies have evaluated schizotypal personality disorder. Persons with a diagnosis of either schizotypal personality disorder or schizophrenia share the same genetic diathesis (6,7). However, persons with schizotypal personality disorder do not have the potentially confounding history of psychosis or hospitalization. Furthermore, studies of cognitive functions in subjects with NIH-PA Author ManuscriptNIH-PA Author Manuscript NIH-PA Author Manuscript schizotypal personality disorder have reported impairments similar to but less severe than those observed in schizophrenic subjects (8-11).Semantic memory can be thought of in terms of its structure and the processes that operate on it. Recent formulations postulate that the structure of semantic memory is instantiated by a network of semantic features, such that words close in meaning, such as "water," "fish," and "ocean," are well connected with each other, and words of distant meanings, such as "water," "pen," and "free," are not w...

Electrophysiological insights into conceptual disorganization in schizophrenia

“…The absence of significant between-group N400 effect differences in the present study contrasts with other studies where such differences were found to be associated with schizophrenia (Condray et al, 2003;Condray et al, 1999;Kostova et al, 2005;Kostova et al, 2003;Mathalon et al, 2002;Mitchell et al, 1991;Ohta et al, 1999;Strandburg et al, 1997), or with schizotypal personality (Kiang and Kutas, 2005;Kimble et al, 2000;Niznikiewicz et al, 2002), which is thought to share genetic and neurophysiological substrates with schizophrenia (Siever and Davis, 2004). Our results, however, are not an isolated instance, as there are other published reports in which no such differences were detected between schizophrenia patients and controls (Andrews et al, 1993;Koyama et al, 1994;Olichney et al, 1997).…”

Abnormal inhibitory processes in semantic networks in schizophrenia

“…The association between N400 amplitude and severity of thought disorder was also reported (Kostova et al, 2005). The ERP studies suggest that integrative processes at long SOAs are intact in SPD (Niznikiewicz et al, 2002) but they become compromised with increased memory load (Niznikiewicz et al, 2004b). Also, Kiang and Kutas (2005), in a long SOA semantic category priming study in a college population, found reduced N400 to category exemplars and increased N400 amplitude to exemplars to be correlated with the Schizotypal Personality Questionnaire (SPQ), an index of schizotypy, concluding that decreased use of context characterized schizophrenia spectrum individuals.…”

Schizophrenia and the structure of language: The linguist's view

“…Semantic priming can also be studied through the N400 electroencephalographic response (Fogelson et al, 2004); on the use of this technique in schizophrenia, see Mathalon et al (2002), Niznikiewicz et al (1999Niznikiewicz et al ( ), (2002, and the studies reviewed by Minzenberg et al (2002, pp. 713-714).…”