Patterns of evidence integration in schizophrenia and delusion

Resolving the Delusion Paradox

BACKGROUND AND HYPOTHESIS

The neurocomputational framework of predictive processing (PP) provides a promising approach to explaining delusions, a key symptom of psychotic disorders. According to PP, the brain makes inferences about the world by weighing prior beliefs against the available sensory data. Mismatches between prior beliefs and sensory data result in prediction errors that may update the brain's model of the world. Psychosis has been associated with reduced weighting of priors relative to the sensory data. However, delusional beliefs are highly resistant to change, suggesting increased rather than decreased weighting of priors. We propose that this "delusion paradox" can be resolved within a hierarchical PP model: Reduced weighting of prior beliefs at low hierarchical levels may be compensated by an increased influence of higher-order beliefs represented at high hierarchical levels, including delusional beliefs. This may sculpt perceptual processing into conformity with delusions and foster their resistance to contradictory evidence.

STUDY DESIGN

We review several lines of experimental evidence on low- and high-level processes, and their neurocognitive underpinnings in delusion-related phenotypes and link them to predicted processing.

STUDY RESULTS

The reviewed evidence supports the notion of decreased weighting of low-level priors and increased weighting of high-level priors, in both delusional and delusion-prone individuals. Moreover, we highlight the role of prefrontal cortex as a neural basis for the increased weighting of high-level prior beliefs and discuss possible clinical implications of the proposed hierarchical predictive-processing model.

CONCLUSIONS

Our review suggests the delusion paradox can be resolved within a hierarchical PP model.

Belief Inflexibility and Cognitive Biases in Anorexia Nervosa-The Role of the Bias against Disconfirmatory Evidence and Its Clinical and Neuropsychological Correlates

The aim of this study was to explore, in a sample of patients with a diagnosis of AN, the ability to question their first impression and, in particular, the willingness to integrate their prior ideas and thoughts with additional progressive incoming information. A total of 45 healthy women and 103 patients with a diagnosis of AN, consecutively admitted to the Eating Disorder Padova Hospital-University Unit, underwent a broad clinical and neuropsychological assessment. All participants were administered the Bias Against Disconfirmatory Evidence (BADE) task, which specifically investigates belief integration cognitive bias. Acute AN patients showed a significantly greater bias toward disconfirming their previous judgment, in comparison to healthy women (BADE score, respectively, 2.5 ± 2.0 vs. 3.3 ± 1.6; Mann-Whitney test, p = 0.012). A binge-eating/purging subtype of AN individuals, compared to restrictive AN patients and controls, showed greater disconfirmatory bias and also a significant propensity to uncritically accept implausible interpretations (BADE score, respectively, 1.55 ± 1.6 and 2.70 ± 1.97 vs. 3.33 ± 1.63; Kruskal-Wallis test, p = 0.002 and liberal acceptance score, respectively, 1.32 ± 0.93 and 0.92 ± 1.21 vs. 0.98 ± 0.75; Kruskal-Wallis test p = 0.03). Abstract thinking skills and cognitive flexibility, as well as high central coherence, are neuropsychological aspects positively correlated with cognitive bias, in both patients and controls. Research into belief integration bias in AN population could enable us to shed light on hidden dimensional aspects, facilitating a better understanding of the psychopathology of a disorder that is so complex and difficult to treat.

Associations between acceptance of the implausible bias, theory of mind and delusions in first-episode psychosis patients; A longitudinal study

Multiple different cognitive biases, among them the liberal acceptance (LA) bias, have been suggested to contribute to reality distortion in psychotic disorders. Earlier studies have been cross-sectional and considered a limited set of cognitive correlates of psychosis, thus the relationship between LA bias and psychosis remains poorly known. We studied a similar bias (acceptance of the implausible (AOI)) in 62 first-episode psychosis (FEP) patients and 62 control subjects, who watched movie scenes with varying degrees of realism and were asked to evaluate the probability of these events occurring in real life. We assessed theory of mind (ToM) performance using the Hinting task and delusion severity using Brief Psychiatric Rating Scale item 11. We correlated the magnitude of AOI with the severity of delusions and performance in the ToM task. Furthermore, we used 1-year follow-up data from 40 FEP patients and 40 control subjects to disentangle state vs trait-like characteristics of AOI. At baseline FEP patients expressed more AOI than control subjects, and the magnitude of AOI correlated positively with the severity of delusions and negatively with ToM performance. At the one-year follow-up, when most patients were in remission, patients still displayed increased AOI, which no longer correlated with delusions. These findings support the notion that the AOI bias could represent a trait rather than a state feature and support further studies to test the hypothesis that it could be one of the causal factors of psychotic disorders, possibly associated with ToM.

COVID-19 conspiracy ideation is associated with the delusion proneness trait and resistance to update of beliefs

The rapid spread of conspiracy ideas associated with the recent COVID-19 pandemic represents a major threat to the ongoing and coming vaccination programs. Yet, the cognitive factors underlying the pandemic-related conspiracy beliefs are not well described. We hypothesized that such cognitive style is driven by delusion proneness, a trait phenotype associated with formation of delusion-like beliefs that exists on a continuum in the normal population. To probe this hypothesis, we developed a COVID-19 conspiracy questionnaire (CCQ) and assessed 577 subjects online. Their responses clustered into three factors that included Conspiracy, Distrust and Fear/Action as identified using principal component analysis. We then showed that CCQ (in particular the Conspiracy and Distrust factors) related both to general delusion proneness assessed with Peter's Delusion Inventory (PDI) as well as resistance to belief update using a Bias Against Disconfirmatory Evidence (BADE) task. Further, linear regression and pathway analyses suggested a specific contribution of BADE to CCQ not directly explained by PDI. Importantly, the main results remained significant when using a truncated version of the PDI where questions on paranoia were removed (in order to avoid circular evidence), and when adjusting for ADHD- and autistic traits (that are known to be substantially related to delusion proneness). Altogether, our results strongly suggest that pandemic-related conspiracy ideation is associated with delusion proneness trait phenotype.

Resistance to Extinction of Evaluative Fear Conditioning in Delusion Proneness

Delusional beliefs consist of strong priors characterized by resistance to change even when evidence supporting another view is overwhelming. Such bias against disconfirmatory evidence (BADE) has been experimentally demonstrated in patients with psychosis as well as in delusion proneness. In this fMRI-study, we tested for similar resistance to change and associated brain processes in extinction of fear learning, involving a well-described mechanism dependent of evidence updating. A social fear conditioning paradigm was used in which four faces had either been coupled to an unconditioned aversive stimulus (CS+) or not (CS-). For two of the faces, instructions had been given about the fear contingencies (iCS+/iCS-) while for two other faces no such instructions had been given (niCS+/niCS-). Interaction analysis suggested that individuals who score high on delusion-proneness (hDP; n = 20) displayed less extinction of evaluative fear compared to those with low delusion proneness (lDP; n = 23; n = 19 in fMRI-analysis) for non-instructed faces (F = 5.469, P = .024). The resistance to extinction was supported by a difference in extinction related activity between the two groups in medial prefrontal cortex and its connectivity with amygdala, as well as in a cortical network supporting fear processing. For instructed faces no extinction was noted, but there was a larger evaluative fear (F = 5.048, P = 0.03) and an increased functional connectivity between lateral orbitofrontal cortex and fear processing regions for hDP than lDP. Our study links previous explored BADE-effects in delusion associated phenotypes to fear extinction, and suggest that effects of instructions on evaluative fear learning are more pronounced in delusion prone subjects.

Failure of hypothesis evaluation as a factor in delusional belief

INTRODUCTION

In accounts of the two-factor theory of delusional belief, the second factor in this theory has been referred to only in the most general terms, as a failure in the processes of hypothesis evaluation, with no attempt to characterise those processes in any detail. Coltheart and Davies ([2021]. How unexpected observations lead to new beliefs: A Peircean pathway. Consciousness and Cognition, 87, 103037. https://doi.org/10.1016/j.concog.2020.103037) attempted such a characterisation, proposing a detailed eight-step model of how unexpected observations lead to new beliefs based on the concept of abductive inference as introduced by Charles Sanders Peirce.

METHODS

In this paper, we apply that model to the explanation of various forms of delusional belief.

RESULTS

We provide evidence that in cases of delusion there is a specific failure of the seventh step in our model: the step at which predictions from (delusional) hypotheses are considered in the light of relevant evidence.

CONCLUSIONS

In the two-factor theory of delusional belief, the second factor consists of a failure to reject hypotheses in the face of disconfirmatory evidence.

Inflexibility in Reasoning: Comparisons of Cognitive Flexibility, Explanatory Flexibility, and Belief Flexibility Between Schizophrenia and Major Depressive Disorder

Introduction: Inflexibility in reasoning has been suggested to contribute to psychiatric disorders, such as explanatory flexibility in depression and belief flexibility in schizophrenia. However, studies tended to examine only one of the flexibility constructs, which could be related to each other, within a single group of patients. As enhancing flexibility in thinking has become one of the psychological treatment goals across disorders, this study aimed to examine three constructs of flexibility (cognitive flexibility, explanatory flexibility, and belief flexibility) in two psychiatric groups. Methods: We compared three groups of participants: (i) 56 outpatients with a schizophrenia-spectrum disorder and active delusions, (ii) 57 outpatients with major depressive disorder and at least a moderate level of depression, and (iii) 30 healthy controls. Participants were assessed on symptom severity and flexibility, using the Trail-Making Task, the Attributional Style Questionnaire, the Maudsley Assessment of Delusions Scale (MADS) and the Bias Against Disconfirmatory Evidence (BADE) Task. Results: Cognitive flexibility was reduced in the two clinical groups compared to controls. Explanatory flexibility was comparable across groups. The three groups differed in belief flexibility measured by MADS but not by the BADE task. Response to hypothetical contradiction was reduced in the delusion group than the other two groups, and the ability to generate alternative explanations was reduced in the delusion group than healthy controls. Discussion: We found an effect of diagnosis on cognitive flexibility, which might be confounded by differences in intellectual functioning. Reduced belief flexibility tended to be specific to delusions.

Combined Neurocognitive And Metacognitive Rehabilitation In Schizophrenia: Effects On Bias Against Disconfirmatory Evidence

Background

A Metacognitive Training for Schizophrenia patients (MCT) was developed to target the cognitive biases that characterize the illness. Results suggest positive MCT effects encompassing several aspects of psychopathology and subjective well-being. There are still open questions concerning the effect on different cognitive biases and the interplay between them and both psychopathology and neurocognition. Specifically, the bias against disconfirmatory evidence (BADE) has never been tested in previous trials on MCT. In this study we evaluated the feasibility of MCT combined with a cognitive remediation therapy (CACR) in schizophrenia and its effect on BADE. Moreover, we investigated the relationships between BADE and both neuropsychology and psychopathology, taking into account mutual influences on the degree of improvement.

Methods

Fifty-seven schizophrenia outpatients were randomly assigned to CACR + control group or MCT+CACR and assessed at baseline and after treatment for psychopathology, neurocognition and BADE.

Results

After MCT+CACR patients showed significantly greater improvements on BADE. Although BADE baseline performances correlated with several cognitive domains, no association was found between BADE improvement and neurocognitive nor psychopathological measures.

Conclusions

This study enlightened for the first time the efficacy of MCT+CACR on BADE in schizophrenia, suggesting the importance to develop a more specific intervention tailored on individual needs of patients.

Dual-process theory, conflict processing, and delusional belief

Many reasoning biases that may contribute to delusion formation and/or maintenance are common in healthy individuals. Research indicating that reasoning in the general population proceeds via analytic processes (which depend upon working memory and support hypothetical thought) and intuitive processes (which are autonomous and independent of working memory) may therefore help uncover the source of these biases. Consistent with this possibility, recent studies imply that impaired conflict processing might reduce engagement in analytic reasoning, thereby producing reasoning biases and promoting delusions in individuals with schizophrenia. Progress toward understanding this potential pathway to delusions is currently impeded by ambiguity about whether any of these deficits or biases is necessary or sufficient for the formation and maintenance of delusions. Resolving this ambiguity requires consideration of whether particular cognitive deficits or biases in this putative pathway have causal primacy over other processes that may also participate in the causation of delusions. Accordingly, the present manuscript critically evaluates whether impaired conflict processing is the primary initiating deficit in the generation of reasoning biases that may promote the development and/or maintenance of delusions. Suggestions for future research that may elucidate mechanistic pathways by which reasoning deficits might engender and maintain delusions are subsequently offered.

Fast and slow thinking in distressing delusions: A review of the literature and implications for targeted therapy

The recent literature on reasoning biases in psychosis and delusions is reviewed. The state-of-the-art knowledge from systematic reviews and meta-analyses on the evidence for jumping to conclusions is briefly summarised, before a fuller discussion of the more recent empirical literature on belief flexibility as applied to delusions. The methodology and evidence in relation to studies of belief flexibility and the Bias Against Disconfirmatory Evidence (BADE) across the delusional continuum will be critically appraised, and implications drawn for improving cognitive therapy. It will be proposed that dual process models of reasoning, which Kahneman (Kahneman, 2011) popularised as 'fast and slow thinking', provide a useful theoretical framework for integrating further research and informing clinical practice. The emergence of therapies which specifically target fast and slow thinking in people with distressing delusions will be described.

Measuring bias against disconfirmatory evidence: An evaluation of BADE task scoring methods and the case for a novel method

Research suggests that bias against disconfirmatory evidence (BADE) may help maintain delusions in the face of overwhelming evidence against them. Much of this research has employed Woodward and colleagues' BADE task. Different methods of scoring this task, many of which have significant drawbacks, are currently used by researchers, making it difficult to compare results across studies of BADE. Continued advancement of BADE research demands a scoring method with more favorable psychometric properties that is used more consistently by researchers. Here, we take a data-driven but theory-informed approach to the development of a new method for scoring the BADE task. This new scoring procedure is more parsimonious than previous metrics of BADE but captures the vast majority of their predictive variance in relation to delusions. This new method may therefore be capable of inspiring consensus use among BADE researchers. If so, it could significantly increase the ease of comparing future studies of BADE.

Self-Reported Cognitive Biases Are Equally Present in Patients Diagnosed With Psychotic Versus Nonpsychotic Disorders

We investigated the relation between subjective cognitive biases measured with the Dutch Davos Assessment of Cognitive Biases (DACOBS-NL) and (1) the presence of a psychotic versus nonpsychotic psychiatric disorder, (2) the current dose of antipsychotic medication and current psychotic symptoms, and (3) the Personality Inventory for the DSM-5 (PID-5) Psychoticism personality trait. Results showed that DACOBS-NL subjective cognitive biases (1) were equally present in patients diagnosed with nonpsychotic disorders compared with patients with a psychotic disorder, (2) could not be explained by the current dose of antipsychotic medication, nor by current psychotic symptoms, and (3) significantly correlated with all PID-5 Personality domains. Moreover, in predicting membership of the psychotic versus nonpsychotic psychiatric disorder group, the addition of the PID-5 domains in step 2 rendered the contribution of the DACOBS-NL subjective cognitive biases in step 1 nonsignificant. Further research is needed to clarify the interplay between cognitive biases and aberrant salience in the prediction of psychotic disorders.

Holding on to false beliefs: The bias against disconfirmatory evidence over the course of psychosis

BACKGROUND AND OBJECTIVES

The ability to integrate evidence into a reasoning process is crucial in order to react to changing information, e.g. to adapt one's beliefs according to new evidence or to generate new beliefs when facing better alternatives. Evidence integration ability is thus associated with belief flexibility. A specific bias of evidence integration, a bias against disconfirmatory evidence (BADE), can be found in patients with schizophrenia and has been linked to delusion development and maintenance. Knowledge about whether the BADE occurs already in risk constellations of psychosis can clarify its role in the pathogenesis of psychosis.

METHODS

This article reviews the current literature on BADE. Many studies demonstrate BADE over the course of illness, ranging from healthy controls with subclinical properties of schizotypy, over patients with at-risk mental states (ARMS) and patients with a first episode of psychosis to patients with chronic schizophrenia. These data allow a comparison of competences and deficits over the course of illness. Underlying mechanisms of BADE are discussed, including interrelations with neurocognitive performance and dopaminergic processes.

RESULTS

The BADE could be found in different phases of psychosis development and can be regarded as a cognitive marker of the beginning psychotic state.

LIMITATIONS

The presented findings are derived from independent cross-sectional studies. So far, no comprehensive longitudinal assessment has been published.

CONCLUSIONS

Treatments of metacognitive deficits in general and as early as in the ARMS might interfere with the cognitive pathogenesis of psychosis, and thereby ameliorate, postpone or even prevent the transition to psychosis.

Symptom-related attributional biases in schizophrenia and bipolar disorder

INTRODUCTION

Biases in causal attributions and evidence integration have been implicated in delusions, but have not been investigated simultaneously to examine additive or multiplicative effects. It was hypothesised that paranoid delusions would correlate with self-serving and personalising biases ("defence" model of paranoia), particularly when these biases were disconfirmed.

METHODS

Constrained principal component analysis was used to investigate differences between schizophrenia patients (paranoid vs. non-paranoid), bipolar disorder patients, and healthy controls, as well as to examine the extent to which psychotic symptoms could predict patterns of responding on a novel attributional bias task (Attributional Style BADE, or ASB) that requires integrating contextual information.

RESULTS

Although no group differences were found, disorganisation and manic symptoms correlated with situation attributions and self-blame when such attributions were unsupported by the available evidence, and depression and anxiety correlated with other-person and self attributions (not situation attributions) when confirmed by the available evidence, regardless of diagnosis.

CONCLUSIONS

While group differences accounted for little variance in responses on the ASB task, a transdiagnostic association between symptoms of psychosis and the ASB task was observed. This highlights the importance of considering symptom profiles rather than diagnostic groupings when investigating cognitive biases and related non-pharmacological treatments.

Association of the Jumping to Conclusions and Evidence Integration Biases With Delusions in Psychosis: A Detailed Meta-analysis

We completed a meta-analysis to investigate the relationship between delusions in psychosis and 4 cognitive biases: "jumping to conclusions" (JTC), the "bias against disconfirmatory evidence" (BADE), the "bias against confirmatory evidence" (BACE), and "liberal acceptance" (LA). Building on recent meta-analyses we compared more narrowly defined groups. We identified 35 JTC, 8 BADE, 7 BACE, and 6 LA studies for inclusion. Groups with schizophrenia who were currently experiencing delusions demonstrated greater JTC, BADE, BACE, and LA than groups with schizophrenia who were not currently experiencing delusions, who in turn demonstrated no more JTC than healthy control groups. Hence JTC, BADE, BACE, and LA co-vary with delusions in cross-sectional samples of people with schizophrenia. Groups who were experiencing delusions due to other psychiatric illnesses also demonstrated greater JTC than healthy controls, and equivalent JTC to groups with schizophrenia currently experiencing delusions. Hence JTC is associated with delusions across a range of diagnoses. Groups with other, non-delusional psychiatric illnesses demonstrated less JTC, BADE, BACE, and LA than groups with schizophrenia currently experiencing delusions, less JTC than groups experiencing delusions due to other diagnoses, and no more JTC, BADE, BACE, or LA than healthy control groups. Hence JTC, BADE, BACE, and LA were not associated with psychiatric illnesses in general. Our results indicate all 4 biases are associated with delusions specifically rather than merely with a diagnosis of schizophrenia or with being psychiatrically ill, consistent with the possibility that they contribute to delusional severity.

Bias against disconfirmatory evidence in the 'at-risk mental state' and during psychosis

Prior studies have confirmed a bias against disconfirmatory evidence (BADE) in schizophrenia which has been associated with delusions. However, its role in the pathogenesis of psychosis is yet unclear. The objective was to investigate BADE for the first time in subjects with an at-risk-mental-state for psychosis (ARMS), patients with a first episode of psychosis without antipsychotic treatment (FEP) and healthy controls (HC). A standard BADE test presenting written scenarios was employed. In addition, psychometric rating scales and a neuropsychological test battery were applied. A three-staged image was revealed. FEP-patients showed a significant BADE compared to the other groups. The performance of ARMS-patients lay in between HC and FEP-patients. A trend towards significance became evident for a bias against confirmatory evidence (BACE) in FEP-patients. Results were not attributable to antipsychotic or other medication or depressive symptoms. Correlations with delusions reached medium effect sizes but failed significance after Bonferroni-corrections. These results provide evidence for aberrations in evidence integration in the pathogenesis of psychosis and contribute to our knowledge of metacognitive functioning which can be used for (meta-)cognitive intervention in psychosis.

Metacognitive training for schizophrenia: a systematic review

Background

Metacognitive training (MCT) is a novel group psychotherapy method for schizophrenia, but there is, as yet, no conclusive evidence of its efficacy.

Aims

Conduct a meta-analysis to assess the effectiveness of MCT in schizophrenia.

Methods

Electronic and hand searches were conducted to identify randomized controlled trials about the effects of MCT in schizophrenia that met pre-defined inclusion criteria. The Cochrane Risk of Bias tool was employed to assess of risk of biases, and Cochrane Review Manager version 5.3 and R version 3.1.1 were used to conduct the data synthesis.

Results

Ten trials from 54 unduplicated reports were included in the review, but differences in the methods of assessing outcomes limited the number of studies that could be included in the meta-analysis. Pooling four studies that assessed the positive symptom subscale of the Positive and Negative Syndrome Scale (PANSS) at the end of the trial identified a small but statistically significant greater reduction in the MCT group than in the control group. But pooling four studies that assessed the delusion subscale of the Psychotic Symptom Rating Scales (PSYRATS) at the end of the trial found no significant difference between the groups. Results from the qualitative assessment of the other results that could not be pooled across studies were mixed, some showed a trend in favor of MCT but many found no difference between the groups.

Conclusions

The limited number of RCT trials, the variability of the method and time of the outcome evaluation, and methodological problems in the trials make it impossible to come to a conclusion about the effectiveness of MCT for schizophrenia. More randomized trials that use standardized outcome measures, that use intention-to-treat (ITT) analyses, and that follow-up participants at regular intervals after the intervention are needed to determine whether or not MCT should become a recommended adjunctive treatment for schizophrenia.

Metacognitive group training for forensic and dangerous non-forensic patients with schizophrenia: a randomised controlled feasibility trial

BACKGROUND

In schizophrenia, the presence of certain cognitive biases has been established. Informed by this, metacognitive training (MCT) has been developed for schizophrenia. There is increasing evidence of its effectiveness with some patients, but its applicability to dangerous patients has not yet been demonstrated.

AIMS

Our aim was to test the feasibility of a randomised controlled trial (RCT) of MCT for patients in a high-security hospital setting.

METHODS

Twenty of 33 eligible and selected male in-patients with schizophrenia and a history of violence were randomised pairwise to eight sessions of MCT or treatment as usual. Symptom severity and reasoning, according to the jumping to conclusions paradigm, were measured before, immediately after treatment, and 3 and 6 months later.

RESULTS

Men in both groups completed the trial, and those in the MCT arm, almost all of the group sessions. The MCT arm had a significant advantage in improvement of 'suspiciousness', greatest at 3 months, but then declining. No significant improvement in reasoning ability was achieved.

CONCLUSIONS

Metacognitive training showed sufficient promise in this group for a full trial to be worthwhile, and the feasibility of an RCT methodology, even in a secure hospital, was established. The fact that the improvements faded during follow-up suggests that a useful modification to the treatment would be lengthening the protocol, repeating it, or both.

Impaired integration of disambiguating evidence in delusional schizophrenia patients

BACKGROUND

It has been previously demonstrated that a cognitive bias against disconfirmatory evidence (BADE) is associated with delusions. However, small samples of delusional patients, reliance on difference scores and choice of comparison groups may have hampered the reliability of these results. In the present study we aimed to improve on this methodology with a recent version of the BADE task, and compare larger groups of schizophrenia patients with/without delusions to obsessive-compulsive disorder (OCD) patients, a population with persistent and possibly bizarre beliefs without psychosis.

METHOD

A component analysis was used to identify cognitive operations underlying the BADE task, and how they differ across four groups of participants: (1) high-delusional schizophrenia, (2) low-delusional schizophrenia, (3) OCD patients and (4) non-psychiatric controls.

RESULTS

As in past studies, two components emerged and were labelled 'evidence integration' (the degree to which disambiguating information has been integrated) and 'conservatism' (reduced willingness to provide high plausibility ratings when justified), and only evidence integration differed between severely delusional patients and the other groups, reflecting delusional subjects giving higher ratings for disconfirmed interpretations and lower ratings for confirmed interpretations.

CONCLUSIONS

These data support the finding that a reduced willingness to adjust beliefs when confronted with disconfirming evidence may be a cognitive underpinning of delusions specifically, rather than obsessive beliefs or other aspects of psychosis such as hallucinations, and illustrates a cognitive process that may underlie maintenance of delusions in the face of counter-evidence. This supports the possibility of the BADE operation being a useful target in cognitive-based therapies for delusions.

Neurocognitive capabilities modulate the integration of evidence in schizophrenia

Previous studies have demonstrated a cognitive bias in the integration of disconfirmatory evidence (BADE) in patients with schizophrenia. This bias has been associated with delusions. So far, it is unclear how the integration of evidence is associated with neurocognitive capabilities. In the current study, 31 patients with schizophrenia and 29 healthy controls, matched on age, gender, education and premorbid verbal intelligence, underwent a BADE task. Written scenarios of three consecutive sentences each were presented, which progressively reduced the ambiguity of situations. Participants were asked to rate the plausibility of four possible interpretations and adjust their ratings in response to the provided sentences. Psychometric rating scales and a neuropsychological test battery were applied. Patients displayed a bias in the integration of confirmatory, but not disconfirmatory evidence and a liberal acceptance of belief formation. Correlation analyses revealed no associations of evidence integration with the severity of positive symptoms, but with neurocognitive domains, especially with processing speed, executive functioning, vigilance and working memory. In conclusion, patients with schizophrenia show a bias in evidence integration. Neurocognitive functioning emerged as a modulatory factor that should be considered in further research. Studies investigating BADE in earlier stages of psychosis will be necessary to reveal causal relationships.

The Cognitive Biases Questionnaire for Psychosis (CBQ-P) and the Davos Assessment of Cognitive Biases (DACOBS): validation in a Flemish sample of psychotic patients and healthy controls

OBJECTIVE

A large body of research has demonstrated the importance of cognitive biases in the development and maintenance of psychosis. Self-report scales for routine clinical practice have been developed only recently. Two new instruments on cognitive biases are evaluated: the Cognitive Biases Questionnaire for Psychosis and the Davos Assessment of Cognitive Biases Scale.

METHODS

In a Flemish sample of 98 patients diagnosed with schizophrenia and 152 healthy controls, we investigated (1) the factor structure, (2) the reliability (internal consistency), (3) the discriminative power and (4) the convergent validity of the Dutch CBQ-P and the DACOBS.

RESULTS

Using Confirmatory Factor Analysis, a 1-factor solution provided the best fit for the CBQ-P, and a 3-factor solution for the DACOBS. The CBQ-P Total Scale and the three scales of the DACOBS showed good internal consistencies. The CBQ-P Total Scale and all three DACOBS subscales were able to differentiate between healthy controls and patients diagnosed with schizophrenia, when controlling for age and years of education. The CBQ-P and DACOBS scales showed moderate correlations, confirming the convergent validity of both scales.

CONCLUSIONS

The CPQ-P and DACOBS appear to be psychometrical sound instruments to assess general thinking bias in psychosis within a Flemish population. Implications for future research are discussed.