Context processing in schizotypal personality disorder: Evidence of specificity of impairment to the schizophrenia spectrum.

Abstract

Working memory abnormalities, which are particularly pronounced on context processing tasks, appear relatively specific to schizophrenia spectrum illnesses compared with other psychotic disorders. However, the specificity of context processing deficits to schizotypal personality disorder (SPD), a prototype of schizophrenia, has not been studied. The authors administered 3 versions of the modified AX Continuous Performance Test and an N-back working memory test to 63 individuals with SPD and 25 with other personality disorders, as well as 42 healthy controls. For the AX Continuous Performance Test standard and degraded versions, there was a significant Trial Type × Delay × Group interaction, as SPDs made significantly more errors reflecting poor maintenance of context and fewer errors reflecting good maintenance of context. SPDs also demonstrated poor performance on the N-back, especially at the 2-back condition. Context processing errors and N-back accuracy scores were related to disorganization symptoms. These findings, which are quite similar to those previously reported in patients with schizophrenia, suggest that context processing deficits are specific to the schizophrenia spectrum and are not a reflection of overall psychopathology. Cognitive limitations are a core component of schizophrenia and other schizophrenia spectrum disorders, frequently preceding the onset of the illness and persisting even after the remission of most other symptoms (Bowie & Harvey, 2005;Heinrichs, 2005). Furthermore, cognitive deficits predict poorer medication (Burton, 2005) and overall treatment adherence (Prouteau et al., 2005), reduced everyday living and social skills (Bowie & Harvey, 2005), and increased tendency for relapse in first-episode patients (Chen et al., 1998). Individuals with schizophrenia demonstrate mild to moderate impairment across a broad range of neuropsychological abilities, with what appears to be more severe impairment in tasks related both to working and episodic memory and to executive functioning (Green, 2006;Mishara & Goldberg, 2004). Although these cognitive limitations in schizophrenia tend to be pervasive in nature, affecting many areas of neuropsychological functioning (Davidson et al., 1995;Heaton et al., 2001;Saykin et al., 1994), new research and theory suggest that working memory may be a core deficit that underlies some of the other cognitive impairments in schizophrenia (Cohen & Servan-Schreiber, 1992;Silver, Feldman, Bilker, & Gur, 2003), as well as other spectrum disorders, such as schizotypal personality disorder (SPD).SPD is a schizophrenia spectrum disorder closely linked with the symptom profile of schizophrenia (Siever, 1995). In addition to demonstrating characteristic clinical symptoms, SPD patients demonstrate cognitive impairment in several ability areas, such as executive functioning (Diforio, Walker, & Kestler, 2000), verbal learning and abstraction (Bergman et al., 1998;Voglmaier, Seidman, Salisbury, & McCarley, 1997), recognition memory (Cadenhead, Perry, Shafer, & B...

Impaired Context Processing is Attributable to Global Neuropsychological Impairment in Schizophrenia and Psychotic Bipolar Disorder

“…In exploratory follow-up analyses, relatives with elevated psychosis spectrum personality traits differed, albeit mildly, from controls and those relatives without such traits on sensitivity to detect targets. This finding is consistent with studies demonstrating impaired performance on expectancy tasks among individuals with schizotypal personality disorder, 14 suggesting that this may track with clinical expression along the psychosis spectrum. While performance measures were moderately familial across all 3 psychosis pedigrees, the modest deficits observed only among those relatives with elevated psychosis spectrum personality traits provide limited support for context processing as an endophenotype for psychosis.…”

“…2,[7][8][9][10][11] Findings of impaired context processing among unaffected relatives 9,12,13 and among those with schizoptypal personality disorder have also been reported, 14 suggesting that impairment in this ability may represent an endophenotype for schizophrenia.…”

Schizotypy and language: A review

“…An analogous reduction in the use of semantic context to activate related concepts could account for attenuated semantic priming effects in schizotypy. Reduced context use in schizotypy has been proposed to result from deficits in maintaining context in working memory (WM; Barch et al, 2004;Kiang & Kutas, 2005;McClure, Barch, Flory, Harvey, & Siever, 2008;McClure et al, 2007;Mitropoulou et al, 2005). Indeed, SPD is associated with WM deficits in the presence of normal general intelligence (Mitropoulou et al, 2005;Siever & Davis, 2004).…”

Exposure to Kynurenic Acid During Adolescence Produces Memory Deficits in Adulthood

“…18 These findings are consistent with evidence that persons with schizophrenia experience deficits in spatial and contextual learning and memory. 19,20 Most of these prior studies of the effects of elevated KYNA concentration on cognitive function in mice or rats have examined adult subjects and the effects of acute treatment with L-KYN to temporarily increase KYNA levels. However, increased concentration of KYNA in the brains of persons with schizophrenia may occur over a much longer period of time.…”