Moment-to-moment associations between negative affect, aberrant salience, and paranoia.

INTRODUCTION: There is an ongoing debate about whether negative affect are consequences or triggers of paranoid thinking. It has also been suggested that aberrant salience is central to the development of delusions. This study modelled the moment-to-moment relationships between negative affect, aberrant salience, and paranoia in acute inpatients with psychosis. METHODS: Participants with active paranoid delusions were assessed using clinical rating scales and experience sampling method (ESM) over 14 days. ESM data were analysed using time-lagged multilevel regression modelling. RESULTS: Both negative affect and aberrant salience predicted an increase in paranoia at the next time point. Conversely, the level of paranoia did not predict subsequent changes in negative affect or aberrant salience. Negative affect predicted an increase in aberrant salience at the next time point, and vice versa. CONCLUSIONS: Negative affect and aberrant salience appear to drive and exacerbate paranoia, rather than being merely the sequelae of the symptom. Our results suggest both direct and indirect (via aberrant salience) pathways from negative affect to paranoia.

Moderators of noise-induced cognitive change in healthy adults.

Environmental noise causes cognitive impairment, particularly in executive function and episodic memory domains, in healthy populations. However, the possible moderating influences on this relationship are less clear. This study assessed 54 healthy participants (24 men) on a cognitive battery (measuring psychomotor speed, attention, executive function, working memory, and verbal learning and memory) under three (quiet, urban, and social) noise conditions. IQ, subjective noise sensitivity, sleep, personality, paranoia, depression, anxiety, stress, and schizotypy were assessed on a single occasion. We found significantly slower psychomotor speed (urban), reduced working memory and episodic memory (urban and social), and more cautious decision-making (executive function, urban) under noise conditions. There was no effect of sex. Variance in urban noise-induced changes in psychomotor speed, attention, Trail Making B-A (executive function), and immediate recall and social noise-induced changes in verbal fluency (executive function) and immediate recall were explained by a combination of baseline cognition and paranoia, noise sensitivity, sleep, or cognitive disorganization. Higher baseline cognition (but not IQ) predicted greater impairment under urban and social noise for most cognitive variables. Paranoia predicted psychomotor speed, attention, and executive function impairment. Subjective noise sensitivity predicted executive function and memory impairment. Poor sleep quality predicted less memory impairment. Finally, lower levels of cognitive disorganization predicted slower psychomotor speed and greater memory impairment. The identified moderators should be considered in studies aiming to reduce the detrimental effects of occupational and residential noise. These results highlight the importance of studying noise effects in clinical populations characterized by high levels of the paranoia, sleep disturbances, noise sensitivity, and cognitive disorganization.

Cognitive Behavioral Therapy Normalizes Functional Connectivity for Social Threat in Psychosis.

Psychosis is often characterized by paranoia and poor social functioning. Neurally, there is evidence of functional dysconnectivity including abnormalities when processing facial affect. We sought to establish whether these abnormalities are resolved by cognitive behavioral therapy for psychosis (CBTp). The study involved 38 outpatients with one or more persistent positive psychotic symptoms, and 20 healthy participants. All participants completed an implicit facial affect processing task during functional magnetic resonance imaging (fMRI). Subsequently, patients either continued to receive standard care only (SCO,n= 16) or received CBTp on top of standard care (+CBTp,n= 22), with fMRI repeated 6-8 months later. To examine the mechanisms underlying CBTp-led changes in threat processing and appraisal, functional connectivity during the social threat (angry faces) condition was assessed separately from left amygdala and right dorsolateral prefrontal cortex (DLPFC) seeds. At baseline, patients, compared with healthy participants, showed greater amygdala connectivity with the insula and visual areas, but less connectivity with somatosensory areas. These differences normalized following CBTp and, compared with the SCO group, the +CBTp group showed greater increases in amygdala connectivity with DLPFC and inferior parietal lobule, with the latter correlating with improvement in positive symptoms. From the DLPFC seed, the +CBTp (compared with SCO) group showed significantly greater increase in DLPFC connectivity with other prefrontal regions including dorsal anterior cingulate and ventromedial prefrontal cortex. These findings indicate that CBTp strengthens connectivity between higher-order cognitive systems and those involved in threat and salience, potentially facilitating reappraisal.

Changes in delusional dimensions and emotions over eight weeks of antipsychotic treatment in acute patients.

Delusional experiences can be considered on a range of dimensions including conviction, distress, preoccupation, and disruption, which have been shown to be related to depression and anxiety. This study aimed to test the hypotheses that delusional conviction is less responsive to antipsychotic treatment than delusional distress and preoccupation, and that depression and anxiety reduce alongside improvements in delusional dimensions. Forty acutely ill inpatients with delusions were assessed during their early stage of antipsychotic treatment. Interview data were analysed using mixed models for repeated measures. There was a significant reduction in psychotic symptoms over eight weeks, after controlling for baseline dosage of antipsychotics. We found no differential rate of improvement across delusional dimensions, and all dimensions improved over time. However, conviction ratings remained relatively high throughout the eight weeks. There was no significant improvement in anxiety and depression, and delusional preoccupation covaried with anxiety and depression throughout eight weeks, suggesting a relationship between emotional and delusional processes during the early recovery phase of psychosis.

Orbitofrontal cortex, emotional decision-making and response to cognitive behavioural therapy for psychosis.

Grey matter volume (GMV) in the orbitofrontal cortex (OFC) may relate to better response to cognitive behavioural therapy for psychosis (CBTp) because of the region׳s role in emotional decision-making and cognitive flexibility. This study aimed to determine the relation between pre-therapy OFC GMV or asymmetry, emotional decision-making and CBTp responsiveness. Emotional decision-making was measured by the Iowa Gambling task (IGT). Thirty patients received CBTp+standard care (CBTp+SC; 25 completers) for 6-8 months. All patients (before receiving CBTp) and 25 healthy participants underwent structural magnetic resonance imaging. Patients׳ symptoms were assessed before and after therapy. Pre-therapy OFC GMV was measured using a region-of-interest approach, and IGT performance was measured as overall learning, attention to reward, memory for past outcomes and choice consistency. Both these measures, were comparable between patient and healthy groups. In the CBTp+SC group, greater OFC GMV correlated with positive symptom improvement, specifically hallucinations and persecution. Greater rightward OFC asymmetry correlated with improvement in several negative and general psychopathology symptoms. Greater left OFC GMV was associated with lower IGT attention to reward. The findings suggest that greater OFC volume and rightward asymmetry, which maintain the OFC׳s function in emotional decision-making and cognitive flexibility, are beneficial for CBTp responsiveness.

Cognitive Biases Questionnaire for psychosis.

OBJECTIVE: The Cognitive Biases Questionnaire for psychosis (CBQp) was developed to capture 5 cognitive distortions (jumping to conclusions, intentionalising, catastrophising, emotional reasoning, and dichotomous thinking), which are considered important for the pathogenesis of psychosis. Vignettes were adapted from the Cognitive Style Test (CST),(1) relating to "Anomalous Perceptions" and "Threatening Events" themes. METHOD: Scale structure, reliability, and validity were investigated in a psychosis group, and CBQp scores were compared with those of depressed and healthy control samples. RESULTS: The CBQp showed good internal consistency and test-retest reliability. The 5 biases were not independent, with a 2-related factor scale providing the best fit. This structure suggests that the CBQp assesses a general thinking bias rather than distinct cognitive errors, while Anomalous Perception and Threatening Events theme scores can be used separately. Total CBQp scores showed good convergent validity with the CST, but individual biases were not related to existing tasks purporting to assess similar reasoning biases. Psychotic and depressed populations scored higher than healthy controls, and symptomatic psychosis patients scored higher than their nonsymptomatic counterparts, with modest relationships between CBQp scores and symptom severity once emotional disorders were partialled out. Anomalous Perception theme and Intentionalising bias scores showed some specificity to psychosis. CONCLUSIONS: Overall, the CBQp has good psychometric properties, although it is likely that it measures a different construct to existing tasks, tentatively suggested to represent a bias of interpretation rather than reasoning, judgment or decision-making processes. It is a potentially useful tool in both research and clinical arenas.

Appraisals and responses to experimental symptom analogues in clinical and nonclinical individuals with psychotic experiences.

OBJECTIVE: Cognitive models of psychosis suggest that anomalous experiences alone do not always lead to clinical psychosis, with appraisals and responses to experiences being central to understanding the transition to "need for care". METHODS: The appraisals and response styles of Clinical (C; n = 28) and Nonclinical (NC; n = 34) individuals with psychotic experiences were compared following experimental analogues of thought interference (Cards Task) and auditory hallucinations (Virtual Acoustic Space Paradigm). RESULTS: The groups were matched in terms of their psychotic experiences. As predicted, the C group scored higher than the NC group on maladaptive appraisals following both tasks, rated the experience as more personally significant, and was more likely to incorporate the experimental setup into their ongoing experiences. The C group also appraised the Cards Task as more salient, distressing, and threatening; this group scored higher on maladaptive-and lower on adaptive-response styles, than the NC group on both tasks. CONCLUSIONS: The findings are consistent with cognitive models of psychosis, with maladaptive appraisals and response styles characterizing the C group only. Clinical applications of both tasks are suggested to facilitate the identification and modification of maladaptive appraisals.

Sensorimotor gating and clinical outcome following cognitive behaviour therapy for psychosis.

BACKGROUND: Prepulse inhibition (PPI) of the startle response refers to the ability of a weak prestimulus to transiently inhibit the response to a closely following strong sensory stimulus. PPI provides an operational index of sensorimotor gating and is reduced, on average, in people with schizophrenia, relative to healthy people. Given the variable response to Cognitive Behaviour Therapy for psychosis (CBTp) and positive associations between pre-therapy brain and cognitive functions and CBT outcome across disorders, we examined whether pre-therapy level of PPI is associated with clinical outcome following CBTp. METHOD: Fifty-six outpatients stable on medication with at least one distressing symptom of schizophrenia and willing to receive CBTp in addition to their usual treatment were assessed on acoustic PPI. Subsequently, 28 patients received CBTp (CBTp+treatment-as-usual, 23 completers) for 6-8months and 28 continued with their treatment-as-usual (TAU-alone, 17 completers). Symptoms were assessed (blindly) at entry and follow-up. RESULTS: The CBTp+TAU and TAU-alone groups did not differ demographically, clinically or in PPI at baseline. The CBTp+TAU group showed improved symptoms relative to the TAU-alone group, which showed no change, at follow-up. Pre-therapy PPI level correlated positively with post-CBTp symptom improvement. CONCLUSIONS: Relatively intact sensorimotor gating is associated with a good clinical response following a 6-8months course of NICE compliant CBTp in schizophrenia. Pharmacological or psychological interventions capable of improving PPI may enhance the effectiveness of CBTp in people with schizophrenia, particularly in those who fail to show clinical improvement with currently available antipsychotic drugs and adjunctive CBTp.

Neural changes following cognitive behaviour therapy for psychosis: a longitudinal study.

A growing body of evidence demonstrates that persistent positive symptoms, particularly delusions, can be improved by cognitive behaviour therapy for psychosis. Heightened perception and processing of threat are believed to constitute the genesis of delusions. The present study aimed to examine functional brain changes following cognitive behaviour therapy for psychosis. The study involved 56 outpatients with one or more persistent positive distressing symptoms of schizophrenia. Twenty-eight patients receiving cognitive behaviour therapy for psychosis for 6-8 months in addition to their usual treatment were matched with 28 patients receiving treatment as usual. Patients' symptoms were assessed by a rater blind to treatment group, and they underwent functional magnetic resonance imaging during an affect processing task at baseline and end of treatment follow-up. The two groups were comparable at baseline in terms of clinical and demographic parameters and neural and behavioural responses to facial and control stimuli. The cognitive behaviour therapy for psychosis with treatment-as-usual group (22 subjects) showed significant clinical improvement compared with the treatment-as-usual group (16 subjects), which showed no change at follow-up. The cognitive behaviour therapy for psychosis with treatment-as-usual group, but not the treatment-as-usual group, showed decreased activation of the inferior frontal, insula, thalamus, putamen and occipital areas to fearful and angry expressions at treatment follow-up compared with baseline. Reduction of functional magnetic resonance imaging response during angry expressions correlated directly with symptom improvement. This study provides the first evidence that cognitive behaviour therapy for psychosis attenuates brain responses to threatening stimuli and suggests that cognitive behaviour therapy for psychosis may mediate symptom reduction by promoting processing of threats in a less distressing way.

Coping styles predict responsiveness to cognitive behaviour therapy in psychosis.

The study aimed to determine the clinical and neuropsychological predictors of responsiveness to cognitive behavioural therapy for psychosis (CBTp). Sixty patients with schizophrenia or schizoaffective disorder and 25 healthy individuals took part in the study. Thirty patients (25 protocol completers) received CBTp in addition to standard care (SC); 30 patients (18 protocol completers) received SC only. All patients were assessed on symptoms using the Positive and Negative Syndrome Scale (PANSS) and clinical and neuropsychological function before and after CBTp. Symptoms and self-esteem improved to a greater extent in the CBTp+SC than SC control group. Greater pre-therapy coping ability and the self-reflectiveness dimension of cognitive insight at baseline predicted improvement in symptoms in the CBTp+SC group, but not the SC control group, explaining up to 21% of the variance in symptom improvement. Pre-therapy neuropsychological function, duration of illness, clinical insight and gender did not predict CBTp responsiveness. Being able to have a range of coping strategies and reflect on one's experiences while refraining from overconfidence in one's interpretations before therapy is conducive to better CBTp responsiveness.

Do antipsychotics improve reasoning biases? A review.

OBJECTIVE: To explore how reasoning biases in schizophrenic patients respond to treatment. Patients with schizophrenia, especially those with delusions, show not only cognitive deficits but also "reasoning biases," namely, "jumping to conclusions," reduced belief flexibility, an externalizing attributional style, and an impaired "theory of mind." METHODS: This is a systematic review of 17 longitudinal and cross-sectional studies. RESULTS: "Jumping to conclusions" and reduced "belief flexibility" are most closely related to the severity of delusions, whereas "theory of mind" is better related to negative symptoms and "attributional style" to overall psychopathology. Antipsychotic treatment leads to an improvement in belief flexibility and theory of mind, with the suggestion that "belief flexibility" may be mediating the treatment response. On the other hand, the "jumping to conclusions" bias is likely a stable "trait" factor, which does not change with treatment, although it may moderate the outcome of response. The findings above are offered with the caveat that most of the available studies are small, often uncontrolled, few are longitudinal, that the measurement of some of the reasoning measures varies across studies, and that their relationship to the more established "cognitive" deficits remains unclear. CONCLUSIONS: The fact that these reasoning biases could be moderators and mediators of treatment outcome provides a greater impetus to study them systematically.

Cognitive insight in psychosis: the relationship between self-certainty and self-reflection dimensions and neuropsychological measures.

Cognitive insight in schizophrenia encompasses the evaluation and reinterpretation of distorted beliefs and appraisals. We investigated the neuropsychological basis of cognitive insight in psychosis. It was predicted that, like clinical insight, cognitive insight would be associated with a wide range of neuropsychological functions, but would be most strongly associated with measures of executive function. Sixty-five outpatients with schizophrenia or schizoaffective disorder were assessed on tests of intelligence quotient (IQ), executive function, verbal fluency, attention and memory, and completed the Beck Cognitive Insight Scale, which includes two subscales, self-certainty and self-reflection. Higher self-certainty scores reflect greater certainty about being right and more resistant to correction (poor insight), while higher self-reflection scores indicate the expression of introspection and the willingness to acknowledge fallibility (good insight). The self-certainty dimension of poor cognitive insight was significantly associated with lower scores on the Behavioural Assessment of Dysexecutive Syndrome; this relationship was not mediated by IQ. There were no relationships between self-reflection and any neuropsychological measures. We conclude that greater self-certainty (poor cognitive insight) is modestly associated with poorer executive function in psychotic individuals; self-reflection has no association with executive function. The self-certainty and self-reflection dimensions of cognitive insight have differential correlates, and probably different mechanisms, in psychosis.

Beyond dopamine: functional MRI predictors of responsiveness to cognitive behaviour therapy for psychosis.

Despite the favourable effects of antipsychotics on positive symptoms of schizophrenia, many patients continue to suffer from distressing symptoms. Additional benefits of cognitive behaviour therapy for psychosis (CBTp) have been reported for approximately 50% of such patients. Given the role of left hemisphere-based language processes in responsiveness to CBT for depression, and language pathway abnormalities in psychosis, this study examined whether pre-therapy brain activity during a verbal monitoring task predicts CBTp responsiveness in schizophrenia. Fifty-two outpatients, stable on antipsychotics with at least one persistent distressing positive symptom and wishing to receive CBTp adjunctive to their treatment-as-usual, and 20 healthy participants underwent fMRI during monitoring of self- and externally-generated (normal and distorted) speech. Subsequently, 26 patients received CBTp for 6-8 months adjunctive to their treatment-as-usual (CBTp + TAU, 20 completers), and 26 continued with their treatment-as-usual (TAU-alone, 18 completers). Symptoms were assessed (blindly) at entry and follow-up. The CBTp + TAU and TAU-alone groups had comparable demographic characteristics, performance and baseline symptoms. Only the CBTp + TAU group showed improved symptoms at follow-up. CBTp responsiveness was associated with (i) greater left inferior frontal gyrus (IFG) activity during accurate monitoring, especially of own voice, (ii) less inferior parietal deactivation with own, relative to others', voice, and (iii) less medial prefrontal deactivation and greater thalamic and precuneus activation during monitoring of distorted, relative to undistorted, voices. CBTp + TAU patients, on average, displayed left IFG and thalamic hypo-activation (

Structural magnetic resonance imaging predictors of responsiveness to cognitive behaviour therapy in psychosis.

BACKGROUND: Responsiveness to cognitive behaviour therapy (CBT) in psychosis may have a neurological basis. This study aimed to determine whether improvement in symptoms following CBT for psychosis (CBTp) in people with schizophrenia is positively associated with pre-therapy grey matter volume in brain regions involved in cognitive processing. METHODS: Sixty outpatients stable on medication with at least one distressing symptom of schizophrenia and willing to receive CBTp in addition to their standard care (SC), and 25 healthy participants underwent magnetic resonance imaging. Subsequently, 30 patients received CBTp (CBTp+SC; 25 completers) for 6-8 months and 30 continued with their standard care (SC; 19 completers). Symptoms in all patients were assessed (blindly) at entry and follow-up. RESULTS: The CBTp+SC and SC groups did not differ clinically at baseline, and only the CBTp+SC group showed improved symptoms at follow-up. Severity of baseline symptoms was not associated with CBTp responsiveness. Reduction with CBTp in positive symptoms was associated with greater right cerebellum (lobule VII) grey matter volume, in negative symptoms with left precentral gyrus and right inferior parietal lobule grey matter volumes, and in general psychopathology with greater right superior temporal gyrus, cuneus and cerebellum (Crus I) grey matter volumes. Grey matter volume in these brain areas did not correlate with the severity of baseline symptoms. CONCLUSION: Grey matter volume of the frontal, temporal, parietal and cerebellar areas that are known to be involved in the co-ordination of mental activity, cognitive flexibility, and verbal learning and memory predict responsiveness to CBTp in patients with psychosis.

Dorsolateral prefrontal cortex activity predicts responsiveness to cognitive-behavioral therapy in schizophrenia.

BACKGROUND: Given the variable response to cognitive-behavioral therapy (CBT) when added to antipsychotic medication in psychosis and the evidence for a role of pretherapy level of frontal lobe-based cognitive function in responsiveness to CBT in other disorders, this study examined whether pretherapy brain activity associated with working memory neural network predicts clinical responsiveness to CBT in schizophrenia. METHODS: Fifty-two outpatients stable on medication with at least one distressing symptom of schizophrenia and willing to receive CBT in addition to their usual treatment and 20 healthy participants underwent functional magnetic resonance imaging during a parametric n-back task. Subsequently, 26 patients received CBT for psychosis (CBT+treatment-as-usual [TAU], 19 completers) for 6-8 months, and 26 continued with TAU alone (17 completers). Symptoms in both patient groups were assessed (blindly) at entry and follow-up. RESULTS: The CBT+TAU and TAU-alone groups did not differ clinically or in performance at baseline. The CBT+TAU group showed significant improvement in relation to the TAU-alone group, which showed no change, at follow-up. Stronger dorsolateral prefrontal cortex (DLPFC) activity (within the normal range) and DLPFC-cerebellum connectivity during the highest memory load condition (2-back > 0-back) were associated with post-CBT clinical improvement. CONCLUSIONS: DLPFC activity and its connectivity with the cerebellum predict responsiveness to CBT for psychosis in schizophrenia. These effects may be mediated by PFC-cerebellum contributions to executive processing.

Uncontrollable voices and their relationship to gating deficits in schizophrenia.

BACKGROUND: Prepulse inhibition (PPI) of the startle response refers to the ability of a weak prestimulus to transiently inhibit the response to a closely following strong sensory stimulus. This effect is reduced in a number of disorders known to be associated with impaired gating of sensory, cognitive or motor information. The aim of this study was to investigate PPI deficit in relation to the dimensions of auditory hallucinations in patients with schizophrenia or schizoaffective disorder. METHOD: PPI of the acoustically elicited eye blink startle response was measured electromyographically in 62 patients with schizophrenia (n=55) or schizoaffective disorder (n=7) (26 of 62 with current auditory hallucinations) and 22 healthy participants matched, on average, to age and sex of the patient group. RESULTS: Patients, as a group, showed reduced PPI compared to healthy participants. The presence of auditory hallucinations was associated with a marked PPI deficit if the patients felt that they had no control over their occurrence and that they were unable to dismiss them. Hearing voices with a high degree of negative content was associated with high mean startle amplitude in patients with current auditory hallucinations. CONCLUSIONS: Although auditory hallucinations in patients with schizophrenia are theorised to result from impaired monitoring of inner speech, the inability to consciously ignore them appears to be associated with a gating deficit. Hearing voices with negative content is associated with hyper-startle responding, possibly because such voices are threatening and thus provoke anxiety.

Specificity of the jump-to-conclusions bias in deluded patients.

OBJECTIVE: To investigate the specificity of the 'jump-to-conclusions' (JTC) bias in delusions. METHODS: Thirty-seven psychotic patients were divided into two separate groupings: (1) deluded versus non-deluded individuals and (2) individuals with and without a diagnosis of schizophrenia. Groups were compared on three reasoning tasks ('Beads' task, Wason's 2-4-6 task, and Wason's selection task). RESULTS: Deluded participants had a tendency to show a JTC bias on data-gathering tasks, but no differences were found with the schizophrenia diagnosis grouping. There were no differences between any groups on tasks of general reasoning and probability judgments. CONCLUSION: The results suggest that JTC is specific to delusions rather than diagnosis, and to data gathering rather than a general deficit in reasoning.

Insight in psychosis: influence of cognitive ability and self-esteem.

BACKGROUND: Insight in psychosis has previously been associated with both depression and cognitive ability. Some studies have found a curvilinear relationship between insight and cognitive ability, but the roles of self-esteem and depression have not been taken into account. AIMS: To investigate the relationships between insight and IQ, depression, and self-esteem. METHOD: Correlations between self-reported and observer-rated insight, and measures of IQ, depression and self-esteem were examined in 67 people with psychosis. RESULTS: Better self-reported insight was associated with higher IQ and poorer self-esteem, but not depression. There was some evidence for a curvilinear relationship between IQ and self-reported insight, specifically the ;awareness of illness' dimension, which survived correction for symptom variables. CONCLUSIONS: The relationship between insight and IQ might reflect both the basis of insight in intellectual ability and the influence of a psychological mechanism that preserves self-esteem.

Need for closure and anxiety in delusions: a longitudinal investigation in early psychosis.

This study investigated the role of need for closure (NFC) and anxiety in delusions. The Need For Closure Scale (NFCS) and measures of trait and state anxiety were administered to an early psychosis group with current delusions, a clinical (generalised anxiety disorder--GAD) control group and a non-clinical control group. The battery of questionnaires was repeated at follow-up one year later. The NFCS did not meet criteria for a unidimensional scale and two sub-scales were removed from all further analyses. At baseline the deluded and GAD groups scored significantly higher on the reduced NFCS (NFCS-R) than the control group. Trait anxiety was related to NFCS-R in the GAD and non-clinical control groups, but not in the deluded group. At follow-up all groups scored significantly lower on the NFCS-R, perhaps suggesting a practice effect, although the two clinical groups continued to have higher scores than the non-clinical control group. The recovered and non-recovered deluded groups did not differ on the NFCS-R one year later, unlike in the GAD group where recovered participants had significantly lower scores than the non-recovered. Change scores on the NFCS-R and trait anxiety were correlated at trend level in the GAD and non-clinical control groups, but not in the deluded group. These findings suggest that whilst NFC and trait anxiety are related in non-psychotic groups, NFC may be implicated in the formation of delusions, independently of anxiety, in psychotic individuals.

Perceptual organization deficits in psychotic patients.

It has been proposed that a characteristic of schizophrenic processing is an abnormality of top-down processing. The relationship between impaired top-down processing and symptoms of reality distortion was investigated using a 'degraded interference' task. In this task, fragmented stimuli (Stroop words, control words and crosses) are presented on a computer screen, and the extent to which they are visually integrated is inferred by their interfering properties. It was predicted that psychotic individuals would fail to show an interference effect with degraded Stroop stimuli. This predicts the absence of a delay in reaction time in the experimental condition, which therefore cannot be attributed to a generalized deficit. A sample of inpatients experiencing positive symptoms was compared to a healthy control group. The results provided support for a deficiency in top-down processing, with the psychotic group failing to show the significant degraded interference effect found in the healthy controls. Degraded interference was associated with low verbal IQ, but with no other symptomatic or demographic variables.