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

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. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Dual-task information processing in schizotypal personality disorder: Evidence of impaired processing capacity.

Working memory theories heavily rely on the concept of processing resources and the their efficient deployment. Some recent work with schizophrenia-spectrum patients has suggested that many associated cognitive impairments may be reduced to deficits in working memory, possibly related to reductions in information-processing capacity resources. In this study, 38 patients with schizotypal personality disorder (SPD), 22 patients with other personality disorders, and 14 healthy comparison participants performed a dual-task processing assessment that was designed specifically for use in this type of study. Participants recalled lists of digits at their predetermined maximum digit span and performed box-checking tests, first alone and then in a dual-task format. Instructions included equal prioritization of both tasks. SPD patients had significantly shorter digit spans, and they also showed more deterioration on both tasks. Performance operating characteristics curves indicated that SPD patients' reduced performance was not due to abnormal resource allocation strategies leading to strategic failures. The authors discuss the implications of these processing capacity limitations for understanding both the signature of cognitive impairment within the schizophrenia spectrum and general abnormalities in working memory. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Anhedonia and the experience of emotion in individuals with schizophrenia.

Research shows that individuals with schizophrenia report symptoms of anhedonia when assessed by interview or questionnaire. However, when presented with emotional stimuli, they report emotional experiences that are similar to those of control participants. The authors hypothesized that deficits in working memory and episodic memory contribute to such discrepancies. They administered measures of working and episodic memory, self-report anhedonia questionnaires, and several types of emotional stimuli to 49 individuals with schizophrenia and 47 control participants. All participants reported experiencing similar amounts of pleasant-unpleasant emotion (valence) in response to stimuli, but individuals with schizophrenia reported experiencing less arousal for negative stimuli. Individuals with schizophrenia also reported greater social and physical anhedonia on a traditional anhedonia questionnaire. Disturbances in working memory moderated the relationship between physical anhedonia and participants' emotional experience of positive stimuli. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Encoding and retrieval processes in velo-cardio-facial syndrome (VCFS).

Velo-cardio-facial syndrome (VCFS) is a neurogenetic disorder associated with very high risk for developing schizophrenia. More than half of affected individuals experience transient psychotic symptoms during childhood and a third may develop schizophrenia. Memory regulation deficits disturbing both the encoding and retrieval stages of memory represent core deficits in the cognitive profile associated with schizophrenia. In this study, the authors investigate memory regulation processes in 33 individuals with VCFS along with 33 age- and sex-matched control participants. By using a directed forgetting paradigm and a continuous recognition paradigm, the authors examined selective encoding and suppression of irrelevant contents during retrieval in VCFS. Group comparison analyses revealed comparable performances on selective encoding and recognition accuracy between the VCFS group and control group. However, individuals with VCFS were more likely to make false recognitions and showed deficits in the suppression of irrelevant contents. Results suggest that trait-like deficits of memory regulation in VCFS can be observed during the retrieval stage, while selective encoding remains efficient. Memory regulation processes during retrieval may constitute a trait deficit in the memory profile of individuals with VCFS and may contribute to the cognitive deficits underlying an increased risk for developing schizophrenia in this population. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Context-processing deficits in schizophrenia: Converging evidence from three theoretically motivated cognitive tasks.

To test the hypothesis that the ability to actively represent and maintain context information is a central function of working memory and that a disturbance in this function contributes to cognitive deficits in schizophrenia, the authors modified 3 tasks—the AX version of the Continuous Performance Test Stroop, and a lexical disambiguation task—and administered them to patients with schizophrenia as well as to depressed and healthy controls. The results suggest an accentuation of deficits in patients with schizophrenia in context-sensitive conditions and cross-task correlations of performance in these conditions. However, the results do not definitively eliminate the possibility of a generalized deficit. The significance of these findings is discussed with regard to the specificity of deficits in schizophrenia and the hypothesis concerning the neural and cognitive mechanisms that underlie these deficits. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Psychometrically matched visual-processing tasks in schizophrenia spectrum disorders.

Patients with schizophrenia show deficits in visual perception and working memory, but the relationship between these deficits has not been characterized with psychometrically matched tasks. The authors administered 2 visual discrimination and 6 recognition tasks to 43 schizophrenia spectrum patients and 22 nonpsychiatric subjects. When performing difficulty-matched tasks, spectrum subjects showed more severe impairments for motion compared with form processing. When tasks were matched on true score variance, spectrum subjects exhibited worse performance on both form and motion discrimination, and a differential deficit in motion recognition with a short display duration and long interstimulus interval. These results provide evidence of differential deficits in visual processing in schizophrenia that appear to be dependent on the temporal characteristics of the tasks. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Working and long-term memory deficits in schizophrenia: Is there a common prefrontal mechanism?

This study tested the hypothesis that dorsolateral prefrontal cortex deficits contribute to both working memory and long-term memory disturbances in schizophrenia. It also examined whether such deficits were more severe for verbal than nonverbal stimuli. Functional magnetic resonance imaging was used to assess cortical activation during performance of verbal and nonverbal versions of a working memory task and both encoding and recognition tasks in 38 individuals with schizophrenia and 48 healthy controls. Performance of both working memory and long-term memory tasks revealed disturbed dorolateral prefrontal cortex activation in schizophrenia, although medial temporal deficits were also present. Some evidence was found for more severe cognitive and functional deficits with verbal than nonverbal stimuli, although these results were mixed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Word and tone working memory deficits in schizophrenia

BACKGROUND: Verbal memory deficits have been reported in many studies of patients with schizophrenia. We evaluated the specificity of these deficits by comparing patients and control subjects on several verbal and nonverbal auditory memory tests. METHODS: Performance of stable, medicated outpatients with DSM-III-R diagnoses of schizophrenia (N = 38) was compared with that of healthy subjects (N = 39) on a word list immediate recall task, tone delayed discrimination tasks, and word and tone serial position tasks. Before memory testing, patients were divided into 2 groups based on their ability to perform normally on a screening test requiring pitch discrimination and sustained attention. RESULTS: The nonverbal tests were more difficult for control subjects than the verbal tests. Despite this, patients who performed normally on the screening test of perception and attention performed normally on both nonverbal tests but had highly significant deficits on both verbal tests (P<.001 and P = .02). Patients who performed poorly on the screening test had highly significant performance deficits on all the memory tests. CONCLUSIONS: One subgroup of patients with schizophrenia has a selective deficit in verbal memory despite normal motivation, attention, and general perceptual function. Another group has deficits in multiple aspects of cognitive function suggestive of failure in early stages of information processing.     

Rehearsal in spatial working memory

This article reports 3 experiments that tested a hypothesis regarding the nature of rehearsal in spatial working memory, one in which discrete shifts of spatial selective attention mediate the maintenance of location-specific representations. Experiment 1 demonstrated increases in visual processing efficiency for locations held in working memory, which suggested that attention was oriented toward these locations. Experiment 2 eliminated key alternative explanations for Experiment 1 by using an identical stimulus display with a nonspatial memory task, and little or no facilitation of processing at memorized locations was found under these conditions. Finally, Experiment 3 showed that spatial working memory was impaired when participants were hindered in their ability to attend to memorized locations. It is argued that these results implicate selective spatial attention as a rehearsal mechanism for spatial working memory.     

COMT val158Met and executive control: A test of the benefit of specific deficits to translational research.

The role of catechol-O-methyltransferase (COMT) val158met in prefrontal cortical deficits associated with the liability to schizophrenia remains controversial. This study evaluated 464 healthy adult participants using three measures of executive functions in working memory: a 3-back version of the N-back continuous performance task (CPT) and two variants of the AX-CPT. The interpretability of N-back performance was confounded by possible generalized deficits, whereas the AX variants included internal controls for uncovering specific deficits. There was no relationship between the COMT genotype and N-back performance, whereas val/val individuals had a specific deficit on a dot-pattern version of the AX-CPT. In this case, a specific executive function known as context processing appeared to be compromised. These data suggest that the interpretability gained by including task manipulations to uncover specific deficits can enhance associations between cognitive and genetic levels of analysis. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A Convergent-Divergent Approach to Context Processing, General Intellectual Functioning, and the Genetic Liability to Schizophrenia.

Convergent and divergent validity are critically important in developing psychological measures that reveal interpretable deficits in disordered populations. This article reports on 2 studies that evaluated the validity of context processing measures. In Experiment 1, a confirmatory factor analysis of data from 481 healthy adults established the convergent validity of 2 context processing measures and showed that context processing accounted for significant amounts of variance in standard IQ and working memory measures. In Experiment 2, 20 schizophrenia patients, 16 of their healthy siblings, and 28 controls were evaluated using a novel, short context processing measure, the dot pattern expectancy (DPX) task. The DPX was sensitive to specific deficits in schizophrenia patients and their healthy siblings. These findings support the construct validity of context processing measures, suggest context processing is a component of intellectual functioning, and demonstrate that brief context processing measures remain sensitive to psychopathological deficits. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Psychopathic personality traits associated with abnormal selective attention and impaired cognitive control.

The current study investigated how mechanisms of attention that have been well-characterized in the cognitive psychology literature (Lavie, Hirst, De Fockert, & Viding, 2004; Maylor & Lavie, 1998) may be differentially associated with psychopathic traits in nonincarcerated men. Previous research on cognition and psychopathy indicated that primary psychopathic traits were associated with overfocused attention and/or reduced processing of information peripheral to the focus of attention. Conversely, deficits in executive functioning, such as working memory and cognitive control, were implicated in secondary psychopathic traits. Results revealed a significant relationship between traits typically associated with primary psychopathy (e.g., low anxiety, social dominance, fearlessness, callousness) and reduced processing of task-irrelevant distractors, suggesting diminished basic attentional capacity among individuals high on these traits. In contrast, some characteristics linked to secondary psychopathy (e.g., social alienation, cynicism) showed a positive relationship with impaired working memory functioning, indicative of deficits in cognitive control, whereas other traits (i.e., self-centeredness, antagonism) did not. These results suggest that psychopathic traits are differentially related to selective impairments in attentional functioning, which may help explain the observed heterogeneity in psychopathic manifestations. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Context-processing deficits in schizophrenia: Diagnostic specificity, 4-week course, and relationships to clinical symptoms.

Previous research on schizophrenia suggests that context-processing disturbances are one of the core cognitive deficits present in schizophrenia. However, it is not clear whether such deficits are specific to schizophrenia as compared with other psychotic disorders. To address this question, the authors administered a version of the AX Continuous Performance Test designed to assess context processing in a sample of healthy controls, patients with schizophrenia, and patients with other psychotic disorders. Participants were tested at index (when medication naive and experiencing their first contact with psychiatric services) and 4 weeks later, following medication treatment. At index, patients with schizophrenia and the psychotic comparison group demonstrated similar impairments in context processing. However, context-processing deficits improved in the psychotic comparison group at 4 weeks but did not improve in patients with schizophrenia. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Intrinsic motivation in schizophrenia: Relationships to cognitive function, depression, anxiety, and personality.

The goal of the current project was to assess subjective reports of intrinsic motivation and their relationship to cognitive function, mood, and personality in schizophrenia. The authors used the Motivational Trait Questionnaire to examine 3 components of intrinsic motivation (personal mastery, competitive excellence, motivation related to anxiety). They also examined fluid intelligence, context processing, and working memory, as well as self-reports of mood and personal traits related to motivation. Participants were 66 individuals with schizophrenia or schizoaffective disorder and 44 healthy controls. Self-reports of personal mastery and competitive excellence did not differ between controls and individuals with schizophrenia, though patients did report significantly higher motivation related to anxiety. Among controls, but not patients, self-reports of intrinsic motivation were strongly related to cognitive performance. In contrast, both controls and patients showed similar strong relationships between self-reports of intrinsic motivation and related measures of mood and personality. These results are not consistent with the hypothesis that motivational deficits in schizophrenia reflect impairments in intrinsic motivation. However, they do suggest that the normal relationship between self-reports of intrinsic motivation and cognitive function is disrupted in schizophrenia. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

How well do patients with schizophrenia track multiple moving targets?

It has been demonstrated that patients with schizophrenia perform poorly on tasks that require orienting, focusing, maintaining, and shifting attention. However, it is unknown how patients with schizophrenia can track multiple moving targets. To elucidate this issue, the authors investigated fast and slow multiple-object tracking in patients with schizophrenia (n = 30) and in matched healthy control participants (n = 30) and assessed their relationship with motion perception (velocity discrimination), sustained attention and context processing (Continuous Performance Test, 1-9 version; J. R. Finkelstein, T. D. Cannon, R. E. Gur, R. C. Gur, & P. Moberg, 1997), and object and spatial working memory. Results revealed that patients with schizophrenia displayed impaired performances on multiple-object tracking tasks. Linear regression analysis revealed a specific relationship among object tracking, velocity discrimination, and spatial working memory. In patients with schizophrenia, velocity discrimination and spatial working memory were the predictive factors of multiple-object tracking, whereas in healthy control participants, the single predictive factor was velocity discrimination. Probabilistic regression analysis revealed that only the Continuous Performance Test made significant contribution to discriminating between patients and control participants. These results suggest that multiple-object tracking is impaired in schizophrenia, and that it is specifically associated with motion perception and spatial working memory. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Cognitive impairment in adolescents with schizophrenia

OBJECTIVE: The purpose of this study was to determine whether adolescent schizophrenia is characterized by neuropsychological deficits. METHOD: The performance on a battery of neuropsychological tests of 17 adolescents with schizophrenia (mean age = 15.71 years) was compared with that of 17 normal adolescents (mean age = 15.12 years). RESULTS: Compared with the normal subjects, the patients were impaired on 10 of the 13 measures; larger effect sizes were shown for measures involving working memory and attention than for those involving secondary memory, generative naming, and executive functions. CONCLUSIONS: Adolescents with schizophrenia have generalized cognitive dysfunction, which is most apparent on tests of attention and working memory.     

Endothelin B receptor-mediated vasoconstriction induced by endothelin A receptor antagonist

BACKGROUND: Capacity limitation theories have proved to be surprisingly resilient in characterizing some of the cognitive deficits in schizophrenia. However, this perspective has not generally been applied to short-term verbal memory tasks. We explored this issue by first attempting to ascertain if gross misallocations of processing resources might explain impairments in short-term memory in schizophrenia on a classic digit span task and in a second study by attempting to determine what effects delay and memory set size had on a divided attention short-term verbal memory paradigm. METHODS: In the first study 16 patients with schizophrenia and 21 normal controls received 40 trials of a three digit task and 20 trials of a six digit span task. As the absolute number of digits presented and duration of presentation in two conditions were identical, subjects thus had equivalent 'opportunities' to make errors if distraction, in the sense of misallocation of cognitive resources, were at the root of poor performance. In the second study 15 patients with schizophrenia and 15 normal controls were tested in conditions in which two, four or six words were presented and in which rehearsal was prevented by an interference task (colour naming) for delays of 5, 10 or 15 s. RESULTS: Patients had disproportionate difficulty on the six digit rather than the three digit condition, suggesting that deficits in the verbal working memory short-term store may not be the result of attentional factors. In the second study, patients' performance was differentially worsened by the interference task, by memory set size (i.e. a capacity limitation) and by delay, a measure of decay rate. CONCLUSIONS: In concert, these studies demonstrate that schizophrenia patients have difficulties on verbal short-term memory span tasks not because of misallocation of resources, but rather because of limitations in 'representational capacity' and maintenance of information over delays.     

Longitudinal deficits to attention, executive, and working memory in subtypes of mild cognitive impairment.

Objective: Mild cognitive impairment (MCI) has emerged as a classification for a prodromal phase of cognitive decline that may precede the emergence of Alzheimer's disease (AD). Recent research suggests that attention, executive, and working memory deficits may appear much earlier in the progression of AD than traditionally conceptualized, and may be more consistently associated with the later development of AD than memory processing deficits. The present study longitudinally tracked attention, executive and working memory functions in subtypes of MCI. Method: In a longitudinal study, 52 amnestic MCI (a-MCI), 29 nonamnestic MCI (na-MCI), and 25 age- and education-matched controls undertook neuropsychological assessment of visual and verbal memory, attentional processing, executive functioning, working memory capacity, and semantic language at 10 month intervals. Results: Analysis by repeated measures ANOVA indicate that the a-MCI and na-MCI groups displayed a decline in simple sustained attention (ηp2 = .054) with a significant decline on a task of divided attention (ηp2 = .053) being evident in the a-MCI group. Stable deficits were found on other measures of attention, working memory and executive function in the a-MCI and na-MCI groups. The a-MCI group displayed stable impairments to visual and verbal memory. Conclusions: The results indicate that a-MCI and na-MCI display a stable pattern of deficits to attention, working memory, and executive function. The decline in simple sustained attention in a-MCI and n-MCI groups and to divided attention in a-MCI may be early indicators of possible transition to dementia from MCI. However, further research is required to determine this. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

The Stroop task and attention deficits in schizophrenia: A critical evaluation of card and single-trial Stroop methodologies.

The Stroop task, considered by many to be a paradigmatic measure of selective attention, has often been employed to investigate attention deficits in schizophrenia. Card and single-trial versions of this task have yielded different results. In this study both card and single-trial versions were administered to healthy controls (n?=?24) and patients with schizophrenia (n?=?55). No differences in reaction time (RT) interference were found on either version. On the single-trial version, patients showed greater RT facilitation and error rate interference, evidence for a deficit in selective attention. Methodologic and analytic issues that account for the mixed results from earlier card Stroop studies are addressed. It is concluded that single-trial versions provide greater sensitivity to selective attention pathology in schizophrenia. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Brain attack. Acute therapeutic interventions. Free radical scavengers and antioxidants

This study used tests of content memory (item recognition of words and abstract designs), context memory (order recognition of verbal and nonverbal items), and working memory (recognition at a short retention interval) to examine patterns of performance in 27 schizophrenic patients, 52 chronic alcoholic patients, and 66 healthy control participants. When performance was age- and IQ-adjusted the schizophrenia group was significantly impaired in item and order recognition of verbal and nonverbal material; the alcoholic group was impaired only in order recognition for both material types. Item- and order-recognition deficits in the schizophrenia group were greatest at the shortest retention intervals, a pattern previously observed in patients with Parkinson's disease, suggesting a prominence of a working memory deficit in schizophrenia.