Which psychotic experiences are associated with a need for clinical care?

BACKGROUND: The aims of this study were to identify (1) the factor structure of anomalous experiences across the psychosis continuum; (2) qualitative and quantitative differences in psychotic experiences (PEs) between "non need-for-care" and two clinical groups: psychosis patients and individuals at ultra high risk (UHR) of psychosis. We aimed to distinguish which types of experiences would be related to malign (need-for-care and/or help-seeking) versus benign outcomes. METHODS: Component scores obtained from a Principal Components Analysis of PEs from lifetime scores on the Appraisals of Anomalous Experience Inventory (Brett et al., 2007) were compared across 96 participants: patients diagnosed with a psychotic disorder (n=37), help-seeking UHR people (n=21), and non-clinical individuals presenting with enduring PEs (n=38). RESULTS: A five-component structure provided the best solution, comprising dissociative-type experiences, subjective cognitive deficits, and three separate components relating to "positive" symptoms. All groups reported "positive" experiences, such as ideas of reference and hallucinations, with the non-clinical group displaying more PEs in the Paranormal/Hallucinatory component than both clinical groups. "Cognitive/Attentional anomalies" was the only component where the clinical groups reported significantly more anomalies than the non-clinical group. However psychosis patients reported more frequent first-rank type symptoms and "hypomanic" type PEs than the other groups. DISCUSSION: "Positive" PEs were common across the psychosis spectrum, although first-rank type symptoms were particularly marked in participants diagnosed with a psychotic disorder. Help-seeking and need-for-care were associated with the presence of subjective cognitive disturbances. These findings suggest that anomalies of cognition and attention may be more relevant to poorer outcomes than the presence of anomalous experiences.

Cognitive biases and auditory verbal hallucinations in healthy and clinical individuals.

BACKGROUND: Several cognitive biases are related to psychotic symptoms, including auditory verbal hallucinations (AVH). It remains unclear whether these biases differ in voice-hearers with and without a 'need-for-care'. METHOD: A total of 72 healthy controls, 72 healthy voice-hearers and 72 clinical voice-hearers were compared on the Cognitive Biases Questionnaire for psychosis (CBQp), which assesses 'intentionalizing', 'jumping to conclusions', 'catastrophizing', 'dichotomous thinking' and 'emotional reasoning' in vignettes characterized by two themes, 'threatening events' and 'anomalous perceptions'. RESULTS: Healthy voice-hearers scored intermediately on total CBQp between the control and clinical groups, differing significantly from both. However, on four out of five biases the scores of the healthy voice-hearers were comparable with those of the healthy controls. The only exception was 'emotional reasoning', on which their scores were comparable with the clinical group. Healthy voice-hearers demonstrated fewer biases than the psychotic patients on the 'threatening events', but not the 'anomalous perceptions', vignettes. CBQp scores were related to both cognitive and emotional, but not physical, characteristics of voices. CONCLUSIONS: Most cognitive biases prevalent in clinical voice-hearers, particularly with threatening events themes, are absent in healthy voice-hearers, apart from emotional reasoning which may be specifically related to the vulnerability to develop AVH. The association between biases and both beliefs about voices and distress/emotional valence is consistent with the close links between emotions and psychotic phenomena identified by cognitive models of psychosis. The absence of reasoning biases might prevent the formation of threatening appraisals about anomalous experiences, thereby reducing the likelihood of distress and 'need for care'.

Ethnicity, violent offending, and vulnerability to schizophrenia: a pilot study.

Previous research has highlighted increased risk for schizophrenia in Afro-Caribbeans as well as over-representation in the prison population. This small-scale study examined the relationship between criminality, ethnicity, and psychosis-proneness in a male prison sample. Twenty British Caucasian and 20 Afro-Caribbean prisoners were divided into equal sub-groups of violent and non-violent offenders. Participants completed measures of schizotypy, delusional ideation, and hostility. Afro-Caribbean offenders scored more highly on negative schizotypy and delusional ideation than their Caucasian counterparts. Violent offenders scored more highly on the positive symptoms of schizotypy than non-violent prisoners. Both ethnicity and violent offending may be relevant factors when considering vulnerability to psychosis in the offending population.

Intrusions in trauma and psychosis: information processing and phenomenology.

BACKGROUND: Intrusions are common symptoms of both post-traumatic stress disorder (PTSD) and schizophrenia. It has been suggested that an information processing style characterized by weak trait contextual integration renders psychotic individuals vulnerable to intrusive experiences. This 'contextual integration hypothesis' was tested in individuals reporting anomalous experiences in the absence of a need for care. METHOD: Twenty-six low schizotypes and 23 individuals reporting anomalous experiences were shown a traumatic film with and without a concurrent visuospatial task (VST). Participants rated post-traumatic intrusions for frequency and form, and completed self-report measures of information processing style. It was predicted that, because of their weaker trait contextual integration, the anomalous experiences (AE) group would (1) exhibit more intrusions following exposure to the trauma film, (2) display intrusions characterized by more PTSD qualities and (3) show a greater reduction of intrusions with the concurrent VST. RESULTS: As predicted, the AE group reported a lower level of trait contextual integration and more intrusions than the low schizotypes, both immediately after watching the film and during the following 7 days. Their post-traumatic intrusive memories were more PTSD-like (more intrusive, vivid and associated with emotion). The VST had no effect on the number of intrusions in either group. CONCLUSIONS: These findings provide some support for the proposal that weak trait contextual integration underlies the development of intrusions within both PTSD and psychosis.

It's not what you hear, it's the way you think about it: appraisals as determinants of affect and behaviour in voice hearers.

BACKGROUND: Previous studies have suggested that beliefs about voices mediate the relationship between actual voice experience and behavioural and affective response. METHOD: We investigated beliefs about voice power (omnipotence), voice intent (malevolence/benevolence) and emotional and behavioural response (resistance/engagement) using the Beliefs About Voices Questionnaire - Revised (BAVQ-R) in 46 voice hearers. Distress was assessed using a wide range of measures: voice-related distress, depression, anxiety, self-esteem and suicidal ideation. Voice topography was assessed using measures of voice severity, frequency and intensity. We predicted that beliefs about voices would show a stronger association with distress than voice topography. RESULTS: Omnipotence had the strongest associations with all measures of distress included in the study whereas malevolence was related to resistance, and benevolence to engagement. As predicted, voice severity, frequency and intensity were not related to distress once beliefs were accounted for. CONCLUSIONS: These results concur with previous findings that beliefs about voice power are key determinants of distress in voice hearers, and should be targeted specifically in psychological interventions.

Delusions and belief flexibility in psychosis.

OBJECTIVES: A defining characteristic of delusions is inflexibility. However, it is not known if this is specific to the deluded individual's thinking about delusional beliefs, or whether this might apply more generally to the thinking style of people with delusions. DESIGN: A cross-sectional design was employed comparing belief flexibility, belief dimensions, and extreme responding (ER) across three groups. METHODS: Belief flexibility and dimensions were assessed for two types of beliefs, personally meaningful beliefs (delusional or idiosyncratic beliefs) and standard beliefs. The number of extreme responses endorsed on a questionnaire was also measured. Participants consisted of a currently deluded group (N=17), a remitted delusions group (N=17), both recruited from an early psychosis service, and a non-clinical control group (N=35). RESULTS: Personally meaningful beliefs, whether delusions or other idiosyncratic beliefs, were held with equal conviction and belief flexibility in the three groups. However, on the standard belief, the clinical groups showed less belief flexibility than the control group (with only the remitted group significantly so) and greater ER. Individuals who showed belief flexibility about both types of beliefs displayed less ER than those who were inflexible, and belief flexibility was related to less delusional conviction in the clinical groups. CONCLUSION: These results suggest that belief inflexibility and ER may be characteristics of the thinking styles of individuals with delusions, rather than being specific to the delusional beliefs themselves. This has implications for cognitive behavioural therapy, which might usefully focus on generally thinking style as a preparation for working more directly with delusional beliefs.

Schizotypy, delusional ideation and well-being in an American new religious movement population.

This study extends two previous UK studies that looked at schizotypy in new religious movements (Peters, Day, McKenna & Orbach, 1999a; Day & Peters, 1999) using a similar religious subgroup from a different culture. A sample of American Hare Krishna devotees was compared with a non-religious control group on measures of delusional ideation, schizotypy and general well-being. The Hare Krishna group scored significantly higher than the control group on delusional ideation, but not other aspects of schizotypy or general well-being. They also scored higher on delusional conviction, but not distress and preoccupation. The findings provide cross-cultural confirmation for the notion of a continuum between normality and delusional thinking, and the need to consider delusional beliefs as multi-dimensional-psychological health seems to be predicated not on what you believe, but how you believe it.

The psychological processes underlying symptoms of thought interference in psychosis.

Morrison and colleagues have proposed that auditory hallucinations are the result of cognitive intrusions being misattributed to an external source due to such thoughts being inconsistent with the person's beliefs about his or her own mental processes (metacognitive beliefs). The aim of this study was to investigate the applicability of this model to psychotic symptoms of thought interference. Fifty psychotic patients with and without thought interference were compared on (i) frequency of cognitive intrusions, (ii) metacognitive beliefs, (iii) source monitoring and (iv) appraisals of an unrelated anomalous event (a card trick). As predicted, individuals with thought interference had an increased frequency of cognitive intrusions and of maladaptive metacognitive appraisals, lower perceived cognitive control, and were more likely to endorse appraisals regarding 'permeability' of the mind, on the card trick task, in comparison to individuals without thought interference. No significant differences were found on any measure when the patient group was divided into hallucinators and non-hallucinators, once other variables were controlled for. These findings suggest that Morrison's model may be more parsimonious for symptoms of thought interference than for auditory hallucinations.

Disease, deficit or denial? Models of poor insight in psychosis.

OBJECTIVE: To examine the evidence for the three kinds of aetiological model that dominate the current literature on poor insight in psychosis: clinical models, the neuropsychological model, and the psychological denial model. METHOD: Studies pertaining to one or more of these aetiological models were identified, reviewed and critically evaluated. RESULTS: There is little support for clinical models, partly because they lack testable hypotheses. Several studies reveal a positive relationship between insight and executive function, which may be related to frontal lobe dysfunction. However, the extent to which this relationship is specific and independent of general cognitive impairment remains unclear. There is tentative evidence to support the psychological denial model. Recent data combining the latter two approaches suggest that multiple factors contribute to poor insight. CONCLUSION: Integration of different aetiological models is necessary for a fuller understanding of insight in psychosis. Future research should assess multiple aetiological mechanisms in single investigations.

A quantitative genetic analysis of schizotypal personality traits.

BACKGROUND: Previous twin studies investigating the heritability of schizotypy have often had limited power and have failed to measure the disorganization/social anxiety component. METHOD: Seven hundred and thirty-three female twin pairs, drawn from the Institute of Psychiatry Volunteer Twin Register, completed the Oxford-Liverpool Inventory of Feelings and Experiences and the Peters et al. Delusions Inventory. Structural equation modelling was carried out on scores for MZ and DZ twin pairs. RESULTS: The best fitting models for all scales comprised additive genetic and unique environmental effects. Heritability was estimated at approximately 50% for most scales, although it was lower at 37% for the PDI scale. Multivariate structural equation model fitting revealed a best-fitting model in which additive genetic and unique environmental influences act through a single common pathway for Cognitive Disorganization, Unusual Experiences and the PDI, and through a separate common pathway for Cognitive Disorganization and Introvertive Anhedonia. CONCLUSIONS: The various components of schizotypy are moderately heritable. Multivariate model fitting indicates that at least two latent factor structures are required to account for the covariation between the various components of schizotypy. The positive and negative components of schizotypy are relatively genetically independent, although each in turn may be related to Cognitive Disorganization.

The incidence of schizotypy among cannabis and alcohol users.

Schizotypy research has revealed associations between positive schizotypal symptomatology and substance use but has not related substance use to important schizotypal traits such as anhedonia. Users and nonusers of cannabis and alcohol completed the Oxford-Liverpool Inventory of Feelings and Experiences, the Peters Delusion Inventory, and the Hospital Anxiety and Depression Scale. Cannabis users scored significantly higher on Unusual Experiences, a scale measuring positive schizotypal symptomatology. Both cannabis and alcohol usage were associated with significantly lower scores on Introvertive Anhedonia, which represents negative symptomatology. Delusional ideation and delusional conviction were significantly higher in cannabis users, but for delusional conviction this was only true for users who also drank alcohol. Neither anxiety or depression scores were higher in cannabis users, but delusional ideation correlated with both anxiety and depression, thus providing mixed support for the idea of the "happy schizotype." Overall, these results suggest that cannabis and alcohol usage is related to different dimensions of psychosis-proneness that broadly parallel the relationship between substance use and positive and negative schizophrenic symptoms, thus supporting the continuity view of psychosis and the multidimensionality of psychosis-proneness.

Ethnicity, class and schizotypy.

BACKGROUND: This study investigated whether, similarly to schizophrenia, there is an increased rate of schizotypy among African-Caribbeans in the general population compared with white people in the UK. Since social adversity has been associated with schizophrenia in a number of studies, social class as well as ethnicity was explored. In addition, any differences between the groups in neurotic pathology were investigated. METHODS: Four groups of 12 participants (African-Caribbean, working-class; African-Caribbean, middle-class; white, middle-class; white, working-class) were interviewed using The Oxford-Liverpool Inventory of Feelings and Experiences (O-LIFE), The Peters et al. Delusions Inventory (PDI), The Delusions-Symptoms-State-Inventory (DSSI) and The Hospital Anxiety and Depression Scale (HADS). RESULTS: As predicted, African-Caribbean participants scored higher than the white participants on the PDI. There was a significant interaction between ethnicity and class, with African-Caribbean, working-class participants scoring higher than the other three groups on the PDI as well as on the DSSI. There was an unexpected effect of class, with the middle-classes scoring higher than the working-classes on the O-LIFE category of 'impulsive non-conformity'. CONCLUSIONS: These findings suggest that it is delusional ideation specifically, rather than general schizotypy, that is higher in the African-Caribbean population. However, whether this is a reflection of their social reality or their psychosis proneness is unclear. Furthermore, the results suggest that class is a significant factor in the expression of delusional ideation in African-Caribbeans.

Measurement of delusional ideation in the normal population: introducing the PDI (Peters et al. Delusions Inventory).

The Peters et al. Delusions Inventory (PDI) was designed to measure delusional ideation in the normal population, using the Present State Examination as a template. The multidimensionality of delusions was incorporated by assessing measures of distress, preoccupation, and conviction. Individual items were endorsed by one in four adults on average. No sex differences were found, and an inverse relationship with age was obtained. Good internal consistency was found, and its concurrent validity was confirmed by the percentages of common variance with three scales measuring schizotypy, magical ideation, and delusions. PDI scores up to 1 year later remained consistent, establishing its test-retest reliability. Psychotic inpatients had significantly higher scores, establishing its criterion validity. The ranges of scores between the normal and deluded groups overlapped considerably, consistent with the continuity view of psychosis. The two samples were differentiated by their ratings on the distress, preoccupation, and conviction scales, confirming the necessity for a multidimensional analysis of delusional thinking. Possible avenues of research using this scale and its clinical utility are highlighted.

Reasoning biases in delusion-prone individuals.

OBJECTIVES: The objective was to test whether individuals high in delusional ideation exhibit a reasoning bias on tasks involving hypothesis testing and probability judgments. On the basis of previous findings (e.g. Garety, Hemsley & Wessely, 1991), it was predicted that individuals high in delusional ideation would exhibit a 'jump-to-conclusions' style of reasoning and would be less sensitive to the effects of random variation, in comparison to individuals low in delusional ideation. DESIGN: A non-randomized matched groups design was employed enabling the performance of the delusion prone individuals to be compared to that of a control group. METHOD: Forty individuals, selected from the normal population, were divided into groups high and low in delusional ideation, according to their scores on the Peters et al. Delusions Inventory (Peters, Day & Garety, 1996), and were compared on two tasks involving probability judgment and two tasks involving hypothesis testing. RESULTS: Although no significant differences were found on tasks involving hypothesis testing and the aggregation of probabilistic information, it was found that individuals high in delusional ideation had a 'jump-to-conclusions' style of data gathering and were less sensitive to the effects of random variation, in comparison to individuals low in delusional ideation. CONCLUSIONS: In conclusion, although individuals high in delusional ideation were not found to have a general reasoning bias, some evidence of a more specific bias was found. It is thought that these aberrations may play some role in delusion formation in schizophrenia and paranoia.

'Cognitive inhibition' and positive symptomatology in schizotypy.

The negative priming paradigm (Tipper, 1985) was used to investigate the relationship between 'cognitive inhibition' and symptoms of reality distortion in schizotypy, after previous findings that the negative priming effect is reduced in both acute schizophrenics and high schizotypes (Beech, Powell, McWilliam & Claridge, 1989; Beech, Baylis, Smithson & Claridge, 1989). Following Frith's (1979) model, which suggests that the positive symptoms of schizophrenia are due to a failure of the inhibitory processes which normally limit the contents of consciousness, it was predicted that negative priming would be inversely correlated with levels of positive symptomatology, as measured by the CSTQ (Bentall, Claridge & Slade, 1989). The results supported the hypothesis, which confirms the usefulness of a symptom-oriented approach as well as providing some validation for the concept of schizotypy. It was concluded that high schizotypes, similarly to acute schizophrenics, show a reduction in 'cognitive inhibition', as was predicted by Frith's (1979) model.