AX Continuous Performance Test Research Articles

Context processing and negative symptoms in schizophrenia

The objective of the study was to test the assumption that patients with a high level of negative symptoms show disproportionate impairments of inhibition and multitasking, both representing an underlying context processing mechanism. A total of 26 schizophrenia patients scoring high or low on negative symptoms (Positive and Negative Syndrome Scale) and a group of 13 healthy controls were assessed on measures of response inhibition (AX- Continuous Performance Task, Stroop Test) and multitasking (Dual Task, Trail Making Test). Only the high negative symptoms group showed significantly higher inhibition costs and multitasking costs than healthy controls. In the AX-Continuous Performance Test, inhibition costs exceeded context costs in patients with more severe negative symptoms, while in controls a tendency towards the reverse pattern emerged. There were no statistically significant effects involving the patient group with lower negative symptom scores. The pattern of results suggests that primarily patients with more severe negative symptoms have difficulties benefiting from contextual information. The deficit may manifest itself via increased multitasking costs and increased inhibition costs but also via reduced context costs.

Context processing performance in bipolar disorder patients

Context processing is the adaptive control of current behavior through the use of prior context information. It has been found to be impaired in schizophrenia. Some studies have indicated that, compared with patients with schizophrenia, those with bipolar disorder (BPD) display a similar but less severe neuropsychological pattern of impairment. However, this cognitive dimension has not yet been examined in BPD patients in the existing literature. An expectancy version of the AX continuous performance test (AX-CPT) was administered to 15 bipolar outpatients and 26 healthy controls. Patients with schizophrenia, in which context processing deficits are known to occur, were used as a reference group. Bipolar patients showed a context processing deficit relative to healthy controls, although this was less severe and generalized than in schizophrenia patients. These findings suggest there are milder impairments in context processing in BPD compared with schizophrenia. However, the severity of possible context processing deficits in BPD may have been underestimated in our sample of mostly euthymic outpatients.

Accounting for Cognitive Aging: Context Processing, Inhibition or Processing Speed?

ABSTRACT Age-related deficits in context processing were examined in relationship to two predominant theories of cognitive aging (the Inhibitory Deficit and Processing Speed Models). Older and younger adults completed a measure of context processing (AX Continuous Performance Test (CPT) task) as well as a computerized battery of inhibitory tasks: Stroop, garden path sentences, go no-go, and the stop-signal paradigm. Participants also completed a simple processing speed task. After controlling for baseline differences in processing speed, age effects were detected on the AX-CPT. Smaller, but significant age effects were noted on the Stroop and stop-signal tasks, but no significant age effects were found on the garden path sentence and go no-go tasks. Intertask correlations were weak, providing little evidence for a homogenous or uniform construct of inhibition. The sensitivity of the AX-CPT to cognitive aging is discussed in the context of existing theories of cognitive aging. The authors suggest that deficits in context processing and utilization may underlie cognitive aging phenomena.

Schneider's first rank symptoms and continuous performance disturbance as indices of dysconnectivity of left- and right-hemispheric components of language in schizophrenia

Background Here we investigate pathophysiological dimensions (language disturbance, negative symptoms, lateralisation and the continuous performance test) in relation to ICD-10 and DSM-IV concepts of diagnosis. Methods A total of 32 consecutive psychotic patients with at least one Schneider's first rank symptom (SFRS), 15 depressed patients without SFRS and 17 normal volunteers were assessed with the Clinical Language Disorder Rating Scale (CLANG), SFRS, “pure defect” Huber's basic symptoms (HBS), handedness (Annett's pegboard task), and the A-X Continuous Performance Test (AX-CPT). Results CLANG total score (an index of severity of language disorder) was correlated with the severity of SFRS, a higher leftward shift of handedness, and poorer performance on AX-CPT. Receiver operating characteristic (ROC) analysis showed that only CLANG and AX-CPT variables had adequate predictive validity in separating cases of ICD-10 schizophrenia from other diagnoses. The logistic regression model predicting the presence of ICD-10 schizophrenia was statistically significant using CLANG and AX-CPT variables, but not SFRS or other variables. HBS did not correlate with other variables and did not predict ICD-10 diagnosis. Conclusions A cross-sectional diagnosis based on language disturbance and CPT performance yields a diagnostic construct largely overlapping with the ICD-10 definition of schizophrenia. We suggest that Schneider's first rank symptoms (that play a large role in the DSM-IV concept) can be considered an index of left hemisphere dysconnectivity for language whereas CPT dysfunction reflects dysconnectivity of the right hemisphere for those remoter (“spatial”) associations that are closer to Bleuler's core defect and to the chronicity implicit in the ICD definition. Thus the dimensions of language disturbance in psychosis can be traced to specific cortico-cortical dysconnectivities.

The Effects of Guanfacine on Context Processing Abnormalities in Schizotypal Personality Disorder

The signature of impaired cognition in people with schizotypal personality disorder (SPD) may be centrally related to working memory impairments. Guanfacine, an alpha2A agonist that acts post-synaptically in the prefrontal cortex (PFC), has shown potential for reducing working memory limitations in other populations. This study examined the potential of guanfacine for improving context processing, a feature of working memory, in SPD. 29 individuals with SPD entered into a 4-week, randomized parallel-design, double-blind, placebo-controlled trial of guanfacine treatment, followed by a 4-week open-label extension. A modified version of the AX-Continuous Performance Test (AX-CPT) was administered. On this task, evidence of intact context processing includes few BX errors (false cue, correct probe) and higher levels of AY errors (correct cue, false probe). At the end of double-blind treatment, participants treated with guanfacine demonstrated a significant reduction in BX errors and a small but significant increase in AY errors, a pattern that was not seen in the participants treated with placebo. SPD participants improved in their context processing toward a normal response bias, making fewer BX and more AY errors, after being treated with guanfacine.

Independent Effects of Tobacco Abstinence and Bupropion on Cognitive Function in Schizophrenia

The objective of this study was to examine the effects of tobacco abstinence and bupropion treatment on cognitive functioning in adult smokers with schizophrenia in the setting of a randomized, double-blind, placebo-controlled clinical trial of bupropion for smoking cessation. Fifty-three adults with schizophrenia (DSM-IV) took part in a trial of bupropion for smoking cessation. Subjects were enrolled in the study from August 1999 to March 2003. Forty-five subjects remained in the trial at week 4; 41 subjects, 19 taking bupropion and 22 taking placebo, completed the baseline and week 4 cognitive assessments and were included in the analysis of adjusted effects of abstinence and bupropion treatment on cognitive function. Controlling for bupropion treatment and baseline performance, 7 days of tobacco abstinence was associated with slowed motor speed (finger tapping) but was not associated with worsening of performance on tests of attention (AX Continuous Performance Test [AX-CPT]), verbal learning and memory (California Verbal Learning Test [CVLT]), working memory (digit span), or executive function/inhibition (Stroop) and was not associated with worsening of any clinical measures. Controlling for abstinence status, bupropion was associated with reduction (improvement) in reaction time variability on the AX-CPT and with reduction in perseverative errors on the CVLT. We conclude that 1 week of tobacco abstinence is associated with slowed motor speed but is not associated with detectable worsening in performance on a range of neuropsychological tests or clinical symptoms in the subset of patients who were able to quit smoking. We also conclude that bupropion treatment may be associated with improvement in variability of attention.

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 schizophia. 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.

Symposium: Developmental Perspectives on Infant Temperament

Behavioral inhibition (BI) is an infant temperament characterized by heightened reactivity and negative affect in response to novel people and situations. BI is among the earliest and strongest predictors of future anxiety problems. However, not all children with a history of BI will manifest anxiety problems. A growing body of evidence suggests that proactive control skills may help buffer youth with BI from future anxiety difficulties; yet, it remains unclear how temperament may interact with the development of cognitive control to influence anxiety risk. The present study tested whether enhancements in proactive control occurring during adolescence may reduce risk for anxiety among youth with a history of BI.Participants included 185 adolescents (56% female) whose temperament was assessed during toddlerhood. In adolescence, participants completed anxiety assessments and an AX Continuous Performance Test (AX-CPT) to assess cognitive control strategy. Both assessments were administered at age 13 years and again at 15 years.Latent change score modeling revealed that, on average, participants increasingly used proactive control strategies and experienced worsening anxiety from age 13-15 years. Early BI was associated with a smaller anxiety increase from 13-15 years, but only among participants whose proactive control skills improved at mean or greater rates.The present findings suggest that greater proactive control development during adolescence protects youth with high BI from age-related increases in anxiety. Results support a framework that highlights cognitive control as a key moderator of anxiety risk among children with a history of high BI.