The multifactorial structure of the predisposition to hallucinate and associations with anxiety, depression and stress

Subjective visual (but not auditory) function is associated with anomalous perceptual experiences in community-dwelling older adults

INTRODUCTION

With an increasingly ageing population, understanding sensory impairments and their consequences in older adults is important.

METHODS

The current study sought to examine the contemporaneous relationships between subjective sensory functioning (vision and hearing) and different types of anomalous perceptions (anomalous body-centred self-experiences and anomalous external experiences) in community-dwelling older adults (N = 244, Mage = 71.86 ± 7.65, range = 52-91, 67.6% female) using structural equation modelling.

RESULTS

Poorer self-reported visual functioning was associated both with more anomalous body-centred self-experiences and more anomalous external experiences. However, no associations between self-reported hearing function and anomalous perceptions of any kind were found. Further, those reporting higher levels of loneliness self-reported poorer visual functioning and more anomalous body-centred self-experiences. The potential mediating role of loneliness was also explored. However, the relationship between self-reported visual function and anomalous perceptual experiences was not mediated by loneliness.

CONCLUSIONS

The current cross-sectional findings suggest that poorer self-reported visual-but not hearing-function may be a risk factor for the experience of anomalous perceptions in older adults. Future research should examine these associations using objective measures of hearing and vision and longitudinal designs.

Psychotic experiences and psychological distress in adolescents: an examination of longitudinal bidirectional effects across sex

BACKGROUND

Although the co-occurrence of psychotic experiences (PEs) and psychological distress symptoms is growingly recognized in several previous studies, there is still a lack of literature, which clearly outlines how these two psychopathological entities affect each other over time. This study is intended to add to the literature by examining: (a) the longitudinal, bidirectional associations between PEs and psychological distress in a sample of Tunisian adolescents, and (b) whether these associations are moderated by sex.

METHODS

510 adolescent students (mean age of 16.05 ± 1.01 years, 61.2% females) took part in a prospective longitudinal study. PEs and psychological distress were measured at three occasions over a one-year period. The cross-lagged panel modeling approach was adopted.

RESULTS

The current results showed that the experience of PEs at baseline tended to temporally precede prospective increases in psychological distress (at 6 months), which had in turn led to further exacerbation of psychological distress at 12 months of follow-up. Temporally primary psychological distress symptoms were not a significant predictor for the development of later psychotic symptoms in the whole sample. However, temporal patterns between adolescent distress and psychotic symptoms differed for girls and boys. Endorsing PEs at baseline was followed by greater psychological distress at 6 months, which was in turn associated with a significant increased risk of subsequent exacerbation of PEs at 12 months in boys, whereas psychological distress at 12-month follow-up was significantly predicted by pre-existing PEs in girls.

CONCLUSION

These findings suggest that clinicians and support workers are recommended to take into account different social risk profiles for boys and girls when considering interventions to address PEs and distress in adolescents.

Loneliness and objective social isolation are differentially associated with anomalous perceptions in community-dwelling older adults

INTRODUCTION

Anomalous perceptions are characterised by the subjective experience of a range of distorted and/or hallucinatory percepts. Whilst considerable attention has been paid to the neurocognitive processes contributing to anomalous perceptions amongst older adults, less is known about the social factors (e.g. social isolation, loneliness). Furthermore, it is unknown whether loneliness and social isolation are associated with different types of anomalous perceptions, including anomalous body-centred self-experiences and anomalous external experiences.

METHODS

This study examined the cross-sectional relationships between loneliness, objective social isolation, and anomalous perceptions in a sample of community-dwelling older adults (N = 242, M_age= 71.87 ± 7.73, range = 52-91, 67.8% female) using structural equation modelling.

RESULTS

Higher levels of loneliness were associated with more anomalous body-centred self-experiences and anomalous external experiences. Those reporting more loneliness also reported higher levels of anxiety and depression; however, the relationship between loneliness and anomalous perceptions was not mediated by these factors. Social disconnection from a religious group was associated with more anomalous external experiences and being married/living with a partner was associated with more anomalous body-centred self-experiences.

CONCLUSIONS

These findings suggest that loneliness and social isolation have differential associations with anomalous perceptions in older adults and provide additional evidence that attending to loneliness in older adults is important.

Clinical and Sociodemographic Profile of Psychomotor Agitation in Mental Health Hospitalisation: A Multicentre Study

Psychomotor agitation is characterised by an increase in psychomotor activity, restlessness and irritability. People with psychomotor agitation respond by over-reacting to both intrinsic and extrinsic stimuli, experiencing stress and/or altered cognition. The objective of this study is to assess the clinical and sociodemographic profile of psychomotor agitation in patients with severe mental disorders. The study was carried out in Spain by means of multicentre cross-sectional convenience sampling involving 140 patients who had been admitted to psychiatric hospital units and had experienced an episode of psychomotor agitation between 2018 and 2021.Corrigan's Agitated Behaviour Scale was used to assess psychomotor agitation. The results show that the predominant characteristic in psychomotor agitation is aggressiveness, which is also the most reported factor in patients with severe mental disorder. Patients who also have anxiety develop psychomotor agitation symptoms of moderate/severe intensity. The clinical and sociodemographic profile found in our study is consistent with other studies on the prevalence of psychomotor agitation.

Affective Dysregulation Precedes Emergence of Psychosis-Like Experiences in a Community Sample of Young Adults

Affective dysregulation (AD) among persons with schizophrenia spectrum disorders, involving the tendency to exhibit sensitivity to minor stress and negative affective states, is an important diagnostic feature and relates to poorer functional and clinical outcomes. Studies of persons with elevated risk for psychosis demonstrate similar AD to those with schizophrenia, and literature suggest a potential influence of AD in the transition from psychosis-like symptoms (PLEs) to disorder. Cross-sectional investigations to date have supported the link between AD and psychosis, and longitudinal studies have mostly yielded mixed findings without demonstration of potential causal relationships between AD and psychosis. This study examined the concurrent and predictive relationships between AD and PLE in a community sample of youth (n = 630) with attention to distinct facets of AD as a latent construct, including low resiliency, low reactive control, and negative emotionality, using structural equation to estimate a longitudinal cross-lagged and autoregressive model across 3 study waves from 15 to 24 years of age. As hypothesized, AD in the mid-teen years predicted subsequent PLE 3 years later. In addition, we found that increasing PLE in the end of the teen years related to a subsequent increase in AD in the early 20s. A cross-sectional relationship between AD and PLE in the mid-teen years was also supported. Findings overall describe important relationships between AD and PLE that appear to vary with developmental stage, implicating various factors to inform approaches for identifying youth who may be at risk for subsequent PLE or other mental health conditions.

BNST and amygdala connectivity are altered during threat anticipation in schizophrenia

In schizophrenia, impairments in affect are prominent and anxiety disorders are prevalent. Neuroimaging studies of fear and anxiety in schizophrenia have focused on the amygdala and show alterations in connectivity. Emerging evidence suggests that the bed nucleus of the stria terminalis (BNST) also plays a critical role in anxiety, especially during anticipation of an unpredictable threat; however, previous studies have not examined the BNST in schizophrenia. In the present study, we examined BNST function and connectivity in people with schizophrenia (n = 31; n = 15 with comorbid anxiety) and controls (n = 15) during anticipation of unpredictable and predictable threat. A secondary analysis tested for differences in activation and connectivity of the central nucleus of the amygdala (CeA), which has also been implicated in threat anticipation. Analyses tested for group differences in both activation and connectivity during anticipation of unpredictable threat and predictable threat (p < .05). Relative to controls, individuals with schizophrenia showed stronger BNST-middle temporal gyrus (MTG) connectivity during unpredictable threat anticipation and stronger BNST-MTG and BNST-dorsolateral prefrontal connectivity during predictable threat anticipation. Comparing subgroups of individuals with schizophrenia and a comorbid anxiety disorder (SZ+ANX) to those without an anxiety disorder (SZ-ANX) revealed broader patterns of altered connectivity. During unpredictable threat anticipation, the SZ+ANX group had stronger BNST connectivity with regions of the salience network (insula, dorsal anterior cingulate cortex). During predictable threat anticipation, the SZ+ANX group had stronger BNST connectivity with regions associated with fear processing (insula, extended amygdala, prefrontal cortex). A secondary CeA analysis revealed a different pattern; the SZ+ANX group had weaker CeA connectivity across multiple brain regions during threat anticipation compared to the SZ-ANX group. These findings provide novel evidence for altered functional connectivity during threat anticipation in schizophrenia, especially in individuals with comorbid anxiety.

Changing Attitudes Towards Voice Hearers: A Literature Review

Auditory verbal hallucinations, or voice hearing, is increasingly understood as a common experience. Despite this, voice hearers still experience a great deal of stigma, which can have serious negative impacts on the person's experience of their voices, and their recovery. Research has demonstrated that healthcare professionals may be a major source of the stigma surrounding voice hearing, with service-level implications for the development and delivery of evidence-based interventions. Therefore, reducing this stigma is a critical intervention target. The purpose of this narrative review is to examine evidence for interventions aimed at reducing stigma towards people who hear voices, in populations of healthcare professionals, students, and the general public. The available evidence supports the use of anti-stigma interventions based around direct contact with voice hearers and education about voice hearing. However, further research is necessary in this area to confirm these findings.

Predicting hallucination proneness based on mindfulness in university students: the mediating role of mental distress

As a risk factor of hallucination proneness, the level of mindfulness has not yet been investigated in non-clinical participants. Other potential mediators, such as mental distress (depression, anxiety, and stress) which contribute to hallucination proneness also need to be assessed. This study investigated the mediating effect of mental distress in predicting hallucination proneness based on mindfulness. A number of 168 Iranian university students completed three questionnaires: (1) the five-facet mindfulness questionnaire, (2) the depression, anxiety and stress scale; and (3) the revised hallucination scale. The results showed that there was a significant association between levels of mindfulness and hallucination proneness. Mental distress has a significant effect on four facets of mindfulness questionnaire and an insignificant effect on one facet (awareness) in predicting hallucination. These effects were both direct and indirect. The indirect effect was developed by the mediating role of mental distress.

Cerebellar correlates of visual hallucinations in Parkinson's disease and Charles Bonnet Syndrome

Hallucinations, percepts in the absence of external stimuli, are a shared feature of eye-disease (Charles Bonnet Syndrome, CBS) and Parkinson's disease (PD) thought to arise through pathophysiologically distinct mechanisms: deafferentation and attentional network dysfunction respectively. Recent studies have found an association between visual hallucinations and structural changes in the cerebellum without obvious link to either mechanism. Here, we employed Voxel Based Morphometry (VBM), optimised for the cerebellum using the Spatially Unbiased Infratentorial Template (SUIT), to characterise similarities and differences in cerebellar structure associated with visual hallucinations in PD and CBS. Grey and white matter volume (GMV & WMV) from patients with eye-disease (n = 12 hallucinators; n = 9 non-hallucinators) and PD (n = 7 hallucinators; n = 9 non-hallucinators) was examined in a 2-way ANOVA controlling for age, sex, and intracranial volume. Comparing hallucinators to controls across both groups, lower GMV was found bilaterally within cerebellar lobule VIII extending to IX/VII. GMV reductions were also found in Crus 1, greater in PD than eye-disease. Predominantly within PD, hallucination-related lower WMV was found in the medulla. No regions of increased GMV or WMV were found. A correlation was observed between brainstem WMV and lobule VIIIb GMV suggesting a functional association. Lobule VIII comprises a functional node within the Dorsal Attention Network (DAN), linking these findings to current attentional theories of hallucinations, while Crus 1 is linked to cortical visual processing. These findings provide preliminary evidence of a cerebellar contribution to hallucinations that transcends clinical conditions.

A Cross-National Investigation of Hallucination-Like Experiences in 10 Countries: The E-CLECTIC Study

Hallucination-like experiences (HLEs) are typically defined as sensory perceptions in the absence of external stimuli. Multidimensional tools, able to assess different facets of HLEs, are helpful for a better characterization of hallucination proneness and to investigate the cross-national variation in the frequencies of HLEs. The current study set out to establish the validity, factor structure, and measurement invariance of the Launay-Slade Hallucinations Scale-Extended (LSHS-E), a tool to assess HLEs. A total of 4419 respondents from 10 countries were enrolled. Network analyses between the LSHS-E and the 3 dimensions of the Community Assessment of Psychic Experiences (CAPE) were performed to assess convergent and divergent validity of the LSHS-E. Confirmatory factor analysis was used to test its measurement invariance. The best fit was a 4-factor model, which proved invariant by country and clinical status, indicating cross-national stability of the hallucination-proneness construct. Among the different components of hallucination-proneness, auditory-visual HLEs had the strongest association with the positive dimension of the CAPE, compared with the depression and negative dimensions. Participants who reported a diagnosis of a mental disorder scored higher on the 4 LSHS-E factors. Small effect size differences by country were found in the scores of the 4 LSHS-E factors even after taking into account the role of socio-demographic and clinical variables. Due to its good psychometric properties, the LSHS-E is a strong candidate tool for large investigations of HLEs.

Measurement invariance of the Spanish Launay-Slade Hallucinations Scale-Extended version between putatively healthy controls and people diagnosed with a mental disorder

OBJECTIVES

The current study aimed at evaluating the reliability, convergent and divergent validity, and factor structure of the Spanish Launay-Slade Hallucinations Scale-Extended version (LSHS-E) in people with mental disorders and healthy controls.

METHODS

Four hundred and twenty-two individuals completed the Spanish LSHS-E and the Spanish Community Assessment of Psychic Experiences. The convergent and divergent validity of the LSHS-E was assessed with the three dimensions of the Community Assessment of Psychic Experiences (positive, negative, and depressive dimensions) in healthy controls and people with a mental disorder. Factor structure of the LSHS-E was assessed using confirmatory factor analysis and measurement invariance.

RESULTS

The LSHS-E had a good reliability in healthy controls and people with a mental disorder (Cronbach's = 0.83 and 0.91, respectively). The LSHS-E was more strongly associated with positive psychotic-like experiences than with depressive and negative symptoms. Four factors were found: (a) "intrusive thoughts"; (b) "vivid daydreams"; (c) "multisensory hallucination-like experiences"; and (d) "auditory-visual hallucination-like experiences" that were invariant between the group of healthy controls and people with a mental disorder.

CONCLUSION

The Spanish version of the LSHS-E possesses adequate psychometric properties, and the confirmatory factor analysis findings provide further support for the multidimensionality of proneness to hallucination in clinical and nonclinical samples.

On "Hearing" Voices and "Seeing" Things: Probing Hallucination Predisposition in a Portuguese Nonclinical Sample with the Launay-Slade Hallucination Scale-Revised

The experience of hallucinations is a hallmark of psychotic disorders, but they are also present in other psychiatric and medical conditions, and may be reported in nonclinical individuals. Despite the increased number of studies probing the incidence of nonclinical hallucinations, the underlying phenomenological characteristics are still poorly understood. This study aimed to examine the psychometrics proprieties of the Portuguese adaptation of the 16-item Launay-Slade Hallucinations Scale (LSHS), the phenomenological characteristics of nonclinical hallucinatory experiences in a Portuguese sample, and the relationship between clinical symptoms and hallucination predisposition. Three-hundred-and-fifty-four European Portuguese college students completed the LSHS. Of those, 16 participants with high LSHS scores and 14 with low LSHS scores were further screened for clinical symptoms. A three-factor solution for the LSHS Portuguese version proved to be the most adequate. Intrusive or vivid thoughts and sleep-related hallucinations were the most common. Although, fundamentally perceived as positive experiences, all types of hallucinations were described as uncontrollable and dominating. However, the more pleasant they were perceived, the more controllable they were assessed. In addition, hallucination predisposition was associated with increased clinical symptoms. These results corroborate the lower severity of hallucinations in the general population compared to psychotic individuals. Further, they support an association between clinical symptoms and increased vulnerability to hallucinations. Specifically, increased schizotypal tendencies and negative mood (anxiety and depression) may be related to increased psychotic risk.

Psychotic-Like Experiences and Psychological Distress: The Role of Resilience

BACKGROUND

The occurrence of psychotic-like experiences and schizotypal features in the general nonclinical population may imply a connection with psychosis-related liability.

OBJECTIVE

This study was designed to examine the role of resilience in the relationship of hallucination and delusion-like experiences and schizotypal features to psychological distress in a nonclinical sample.

DESIGN

The study sample (n = 432 university students) was selected through a stratified cluster sampling procedure, and measures of hallucination proneness, delusion proneness, schizotypal personality, and psychological distress were administered.

RESULTS

While all three indices of psychotic-like experiences correlated with one another, only hallucination proneness and schizotypal personality features correlated with psychological distress and only schizotypal traits correlated with resilience. Schizotypy was found to have an indirect effect on distress through resilience.

CONCLUSIONS

Findings imply the possibility of two types of schizotypy, with high or low resilience. It appears that schizotypes with low resilience may be susceptible to adversity and mental disorders, while high resilience may be protective.

How anxiety induces verbal hallucinations

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Anxiety both triggers verbal hallucinations (VHs) and shapes their content.

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A current model that accounts for this in terms of failed anticipation is critiqued.

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An important subset of VHs arise from a particular anxious style of anticipation.

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This anxious anticipation makes an experience of thinking more like one of perceiving.

Verbal hallucinations are often associated with pronounced feelings of anxiety, and it has also been suggested that anxiety somehow triggers them. In this paper, we offer a phenomenological or ‘personal-level’ account of how it does so. We show how anxious anticipation of one’s own thought contents can generate an experience of their being ‘alien’. It does so by making an experience of thinking more like one of perceiving, resulting in an unfamiliar kind of intentional state. This accounts for a substantial subset of verbal hallucinations, which are experienced as falling within one’s psychological boundaries and lacking in auditory qualities.

Hallucinations and inhibitory functioning in healthy young adults with high and low levels of hypomanic personality traits

INTRODUCTION

Hallucinations in schizophrenia and hallucination proneness in healthy young adults are associated with a common cognitive mechanism, namely impaired inhibitory control. Hallucinatory-like experiences also seem related to hypomanic symptoms in non-clinical participants; however, the mechanisms involved are unknown. We sought to examine self-reported hallucinatory/anomalous perceptual experiences in students selected for high versus low levels of hypomanic personality traits, and whether hypomania is characterised by deficient inhibitory control.

METHOD

Undergraduate students with either high (n = 26) or low (n = 28) scores on the Hypomanic Personality Scale-Revised (HPS-20) were compared on: (1) the Launay Slade Hallucination Scale-Revised (LSHS-R), a measure of hallucination proneness, (2) the Cardiff Anomalous Perceptions Scale (CAPS) and (3) the Inhibition of Currently Irrelevant Memories (ICIM) task, an index of intentional inhibition.

RESULTS

The high HPS group had higher total scores, as well as higher frequency (on CAPS only), intrusiveness and distress (CAPS) scores compared to the low HPS group. They also produced significantly more false alarms on the second run of the ICIM task than the low hypomania traits group.

CONCLUSIONS

Frequent, intrusive and distressing perceptual anomalies and proneness to hallucinations tend to occur in healthy individuals with hypomanic personality traits and may be associated with transient difficulties with inhibitory control. Inhibitory control may be a cognitive marker of vulnerability to hallucinations across diagnostic boundaries.

Rate and predictors of psychotic symptoms after Kashmir earthquake

Psychotic symptoms are more common in general population than validated diagnosis of psychosis. There is evidence to suggest that these symptoms, hallucinations, paranoia, elated mood, thought insertion, are part of a spectrum of psychosis and may have association with the same risk factors that determine development of psychosis. These symptoms have an association with exposure to psychological trauma, post-traumatic stress disorder, anxiety and depression. The aim of this study was to explore the prevalence of psychotic symptoms in the population affected by a natural disaster, earthquake in this case and possible correlates of these symptoms. We conducted a cross-sectional survey of a population sample affected by the disaster, comprising of 1,291 individuals, 18 months after 2005 earthquake in Northern Pakistan and Kashmir to look at the prevalence of these symptoms and their correlates. Screening Instrument for Traumatic Stress in Earthquake Survivors and Self-Reporting Questionnaire and Psychosis Screening Questionnaire were used as tools. We examined association between the symptoms of anxiety, depression, PTSD and psychotic symptoms. We performed logistic regression analysis where hallucinations and delusions were dependent variables and demographic and trauma exposure variables were independent variables. The prevalence of psychotic symptoms ranged between 16.8 and 30.4 %. They were directly correlated with symptoms of post-traumatic stress disorder as well as concurrent symptoms of anxiety and depression. Lower level of education had a strong association in all the regression models. For hallucinations, living in a joint family had a negative association and participation in rescue, history of exposure to previous trauma and past psychiatric history had positive association. Paranoia was associated with female gender. Any psychiatric symptom was associated death of a family member, history of past psychiatric illness and living in a tent at the time of interview. Pattern of association of psychotic symptoms is consistent with prior literature and can be understood in the light of stress vulnerability model.

Prevalence and dimensionality of hallucination-like experiences in young adults

BACKGROUND

The study of hallucination-like experiences (HLEs) in non-clinical populations is increasingly used to corroborate etiological models of psychosis. This method capitalizes on the absence of confounding factors that typically affect the study of hallucinations in clinical subjects.

AIM

To estimate the prevalence of HLEs in young adults; validate the mutidimensionality and explore the correlates of latent HLEs clusters.

METHODS

Cross-sectional survey design. The extended 16-item Launay-Slade Hallucination Scale (LSHS-E) and the 12-item General Health Questionnaire (GHQ-12) were administered to 649 Italian college students (males: 47%). Confirmatory factorial analysis was used to test multidimensionality of the LSHS-E. Hierarchical nested, progressively constrained models were used to assess configural, metric and scalar invariance of the LSHS-E. Latent class analysis was used to test the existence of different profiles of responding across the identified hallucination-proneness dimensions.

RESULTS

Factor analysis showed that the four-factor model had the best fit. Factors were invariant across demographic variables and levels of psychological distress. Three latent classes were found: a large class with no HLEs (70% of participants), a multisensory HLEs class (18.8%), and a high hallucination-proneness class (11%). Among those reporting high levels of HLEs, approximately half reported scores indicative of considerable psychological distress.

CONCLUSIONS

Although HLEs have a relatively high prevalence in the general population, the majority of those experiences happen in isolation and are not associated to psychological distress. Approximately half of those individuals experiencing high levels of HLEs report significant psychological distress. This may be indicative of general risk for mental health conditions rather than specific risk for psychosis.

Anxiety and depression in psychosis: a systematic review of associations with positive psychotic symptoms

OBJECTIVE

This review explores the influence of anxiety and depression on the experience of positive psychotic symptoms, and investigates the possibility of a causal role for anxiety and depression in the emergence and persistence of psychosis.

METHOD

A systematic literature search was undertaken, producing a number of papers which comment on the links between anxiety and depression, and the experience of delusions and hallucinations. In addition, evidence which could contribute to our understanding of the causal role of anxiety and depression was highlighted.

RESULTS

The findings show that both anxiety and depression are associated in meaningful ways with the severity of delusions and hallucinations, the distress they elicit and their content. However, the cross-sectional nature of the majority of studies and the focus on certain symptom subtypes tempers the validity of the findings. Data from non-clinical samples, studies which track the longitudinal course of psychosis and those which examine the impact of anxiety and depression on the prognosis for people experiencing psychosis, offer some support for the possibility of an influential role for anxiety and depression.

CONCLUSION

We conclude that anxiety and depression are related to psychotic symptom severity, distress and content and are also linked with sub-clinical experiences, symptom development, prognosis and relapse. These links may imply that anxiety and depression could be targets for therapeutic intervention. The article concludes with suggestions for further research, highlighting avenues which may circumvent the limitations of the body of work as it stands.

The effect of psychological stress and expectation on auditory perception: A signal detection analysis

Both psychological stress and predictive signals relating to expected sensory input are believed to influence perception, an influence which, when disrupted, may contribute to the generation of auditory hallucinations. The effect of stress and semantic expectation on auditory perception was therefore examined in healthy participants using an auditory signal detection task requiring the detection of speech from within white noise. Trait anxiety was found to predict the extent to which stress influenced response bias, resulting in more anxious participants adopting a more liberal criterion, and therefore experiencing more false positives, when under stress. While semantic expectation was found to increase sensitivity, its presence also generated a shift in response bias towards reporting a signal, suggesting that the erroneous perception of speech became more likely. These findings provide a potential cognitive mechanism that may explain the impact of stress on hallucination-proneness, by suggesting that stress has the tendency to alter response bias in highly anxious individuals. These results also provide support for the idea that top-down processes such as those relating to semantic expectation may contribute to the generation of auditory hallucinations.

A metacognitive model of the sense of agency over thoughts

INTRODUCTION

The sense of agency over thoughts is the experience of oneself qua agent of mental action. Those suffering certain psychotic symptoms are thought to have a deficient sense of agency. Here I seek to explain this sense of agency in terms of metacognition.

METHOD

I start with the proposal that the sense of agency is elicited by metacognitive monitoring representations that are used in the intentional inhibition of thoughts. I apply this model to verbal hallucinations and the like and examine the plausibility of this model explaining deficits associated with these symptoms.

RESULTS

By tying the sense of agency to metacognitive inhibition I propose that the loss of a sense of agency in certain psychotic symptoms is accompanied by a particular deficit in the patient's ability to control their own thinking. This is consistent with the experiences of those at high risk of developing hallucinations, who report more intrusive thoughts than controls. The model I present is able to explain why those at risk of developing verbal hallucinations and those suffering from verbal hallucinations have deficits in the intentional inhibition of thought. I defend this account from a possible objection by distinguishing the form of the intentional inhibition deficit displayed by those suffering verbal hallucination from that displayed by those suffering from orbital-frontal cortex lesions and posttraumatic stress disorder.

CONCLUSION

A plausible hypothesis is that the sense of agency over thoughts is elicited by the metacognitive monitoring representation used to intentionally inhibit thoughts. The deficit in the sense of agency over thoughts associated with certain psychotic symptoms could be explained by a failure to properly metacognitively monitor certain thought processes.

Quality of hallucinatory experiences: differences between a clinical and a non-clinical sample

In this study, we asked people from two samples (a clinical one, consisting of patients with schizophrenia, and a non-clinical one, including university students) to complete the Revised Hallucination Scale (RHS) as a self-questionnaire. When the participants responded positively to an item, they were encouraged to provide further detailed descriptions (i.e., examples of their own experiences) concerning that item. We found that the kinds of descriptions provided by the two groups were very different. We suggest that it is not advisable to explore the presence of hallucinations in non-clinical samples using research protocols based exclusively on yes-or-no answers to questionnaires like the RHS. Hallucinatory or hallucinatory-like experiences cannot be reliably and validly assessed without a precise characterization of the phenomenal quality of the experience.

Analysis of the multidimensionality of hallucination-like experiences in clinical and nonclinical Spanish samples and their relation to clinical symptoms: implications for the model of continuity

Numerous studies have found that hallucinatory experiences occur in the general population. But to date, few studies have been conducted to compare clinical and nonclinical groups across a broad array of clinical symptoms that may co-occur with hallucinations. Likewise, hallucination-like experiences are measured as a multidimensional construct, with clinical and subclinical components related to vivid daydreams, intrusive thoughts, perceptual disturbance, and clinical hallucinatory experiences. Nevertheless, these individual subcomponents have not been examined across a broad spectrum of clinically disordered and nonclinical groups. The goal of the present study was to analyze the differences and similarities in the distribution of responses to hallucination-like experience in clinical and nonclinical populations and to determine the relation of these hallucination-like experiences with various clinical symptoms. These groups included patients with schizophrenia, non-psychotic clinically disordered patients, and a group of individuals with no psychiatric diagnoses. The results revealed that hallucination-like experiences are related to various clinical symptoms across diverse groups of individuals. Regression analysis found that the Psychoticism dimension of the Symptom Check List (SCL-90-R) was the most important predictor of hallucination-like experiences. Additionally, increased auditory and visual hallucination was the only subcomponent that differentiated schizophrenic patients from other groups. This distribution of responses in the dimensions of hallucination-like experiences suggests that not all the dimensions are characteristic of people hearing voices. Vivid daydreams, intrusive thoughts, and auditory distortions and visual perceptual distortions may represent a state of general vulnerability that does not denote a specific risk for clinical hallucinations. Overall, these results support the notion that hallucination-like experiences are closer to a quasi-continuum approach and that total scores on these scales explain a state of vulnerability to general perceptual disturbance.

Hallucination-like experiences in the nonclinical population

Unusual subjective experiences are relatively common in the general population and have been associated with an increased level of vulnerability to psychosis. The current study aimed to a) determine the distribution of hallucination-like experiences (HLEs) in a community sample of young adults, b) investigate their dimensional subtypes, and c) test the association of HLEs with indicators of poor mental health. Four hundred thirty-seven participants (men, 41%) completed a battery of questionnaires including the 16-item Launay-Slade Hallucination Scale (LSHS), the 12-item General Health Questionnaire (GHQ-12) and the 21-item Peters et al. Delusions Inventory (PDI). The LSHS correlated significantly with GHQ-12 and PDI. Individuals with higher levels of psychological distress were found to report higher frequencies of the HLEs compared with those in the reference range. Exploratory factor analysis of LSHS produced a four-factor solution: a) "auditory and visual HLEs," b) "multisensory HLEs," c) "intrusive thoughts," and d) "vivid daydreams." The current results provide further support for the multidimensional nature of hallucination proneness in the general population and indicate that some HLEs (particularly those related to intrusiveness of thought) are associated with a lower level of perceived well-being.

Correlates of perceptual distortions in clinical and non-clinical populations using the Cardiff Anomalous Perceptions Scale (CAPS): associations with anxiety and depression and a re-validation using a representative population sample

Although the literature on hallucinations in psychiatric patients shows clear links with anxiety and depression, associations of affect with a wider array of anomalous perceptual experiences have been much less studied. This study investigated patients with psychosis (N=29) and a non-clinical population (N=193) using the Cardiff Anomalous Perceptions Scale (CAPS), a measure of perceptual distortion and associated distress, intrusiveness and frequency; along with measures of depression, anxiety and worry. The study also allowed a re-validation of the CAPS in a more representative sample of the UK population. Moderate, reliable correlations with depression, anxiety and worry were found in the non-clinical population with the association being stronger in psychotic patients. The study re-confirmed that anomalous perceptual experiences are common in the general population and that a significant minority (11.9%) have higher levels than the mean of psychotic patients. Scale reliability and validity were also re-confirmed, and the CAPS score was found to be unrelated to age or gender in either sample. As in the original study, factor analysis produced a three-factor solution, although factor theme was not fully replicated: as before, a cluster of first-rank symptoms emerged, but with equivocal evidence for a temporal lobe factor and no replication of a 'chemosensation' component.

Hallucinations and related perceptual disturbance in a non-clinical Spanish population

BACKGROUND

Several studies have suggested the continuity of psychotic symptoms between the general population and clinical samples, and have shown that, in fact, the predisposition to hallucinations is a multi-dimensional construct. However, there is no agreement concerning the number of factors comprising it or the significance of psychotic-like experiences. An examination of the beliefs associated with these experiences could increase knowledge of the continuity of hallucinations.

AIMS

The purpose of this work was to analyze the structure of the Revized Hallucination Scale (RHS), applied to a sample of Spanish university students to find out the meaning for the participants and their associated beliefs on each item.

METHODS

The RHS was administered to a total of 265 participants. Along with the frequency of each experience, participants were asked to provide an example of each situation described and to what they attributed it.

RESULTS

The results emphasized the presence of four factors that are variously made up of six types of beliefs: personal difficulties; psychological explanations; dreamlike experiences; vivid thoughts; perceptive distortions; and personal desires.

CONCLUSIONS

The relevance of these results with regard to the differences that might exist in hallucinations in clinical and normal populations is discussed.

Psychometric Properties of a Persian Translation of the Launay-Slade Hallucination Scale in an Iranian Population

For the Launay–Slade Hallucination Scale, a 12-item measure of predisposition toward auditory and visual hallucinations, internal consistency and concurrent validity of a Persian version were assessed. The Persian version was administered to 182 men ( M age = 29.8 yr., SD = 12.4) and 118 women ( M age = 28.4 yr., SD = 10.2) from a community population in Iran. Participants were selected at random at the main Shiraz bus terminal for long distance intercity routes. The factor structure, internal consistency, and concurrent validity of the translation were examined. Principal component analysis identified two factors characterized as clinical and subclinical. The current factor structure supported the two-factor model proposed by Serper, Dill, Chang, Kot, and Elliot, but the strength and importance of factors appear to differ between countries and cultures. All scales had good to acceptable estimates of reliability. Data also showed desirable concurrent validity for the Persian version. These findings suggest that the Persian version is, for an Iranian sample, best represented by a two-factor solution.

The relationship between dysphoria and proneness to hallucination and delusions among young adults

Previous research suggests that measures of dysphoria relate to positive schizophrenic symptoms. These relationships have rarely been studied within the dimensionality of psychopathology framework. The present study examined the relationship between 3 distinct aspects of dysphoria (depression and state and trait anxiety) and delusion and hallucination proneness in a nonclinical sample of young adults. A total of 472 participants were assessed on measures of dysphoria and delusion and hallucination proneness. Correlation analyses revealed significant associations between both anxiety and depression and hallucination and delusion proneness, suggesting that the association between dysphoria and positive symptoms is also present at a nonclinical level. Partial correlations, and hierarchical regression models, suggest an independent contribution of depression, over anxiety, in influencing hallucination and delusional proneness. The results are discussed in the framework of the cognitive account of schizophrenia and the dimensional model of psychopathology.

Dissociating the components of inhibitory control involved in predisposition to hallucinations

INTRODUCTION

We have previously linked hallucinations in schizophrenia and hallucination predisposition to poor intentional inhibition. However, these previous studies have not systematically investigated the separable dimensions of inhibitory control involved, namely, intentional versus unintentional, and inhibition versus resistance to interference. The aim of this study was to clarify the critical component(s) of inhibitory control specifically related to hallucination predisposition.

METHODS

The Launay-Slade Hallucination Scale-Revised (LSHS-R) was completed by 589 undergraduate students, from which high- (n=28) and low- (n=25) hallucination predisposition groups were drawn. Participants were administered tasks measuring unintentional inhibition (Brown-Peterson variant task) and intentional resistance to interference (directed ignoring [DI] task).

RESULTS

The high LSHS-R group showed significant difficulties relative to the low LSHS-R group on the DI task only; although these differences did not remain significant when controlling for anxiety or delusional thinking. Regression analyses showed that anxiety, but not delusional thinking, independently contributed to variance in DI task performance above that accounted for by hallucination predisposition.

CONCLUSIONS

Intentional rather than unintentional control of intrusive cognitions appears to play an important role in hallucination predisposition. The results indicate that difficulties with the intentional resistance to interference from concurrent external distractors may be a common mechanism underlying positive schizophrenia symptoms and anxiety. However, given previous findings reported by Paulik, Badcock, and Maybery (2007), we propose that hallucination predisposition is also characterised by a difficulty with the active suppression of intrusive cognitions - that is, intentional inhibition - which is not shared with anxiety or delusional symptoms.

Poor intentional inhibition in individuals predisposed to hallucinations

INTRODUCTION

Intentional inhibition deficits have been found in hallucinating individuals with schizophrenia using the Inhibition of Currently Irrelevant Memories (ICIM) task. This study sought to investigate whether similar difficulties are found in healthy individuals predisposed to hallucinations.

METHODS

The Launay-Slade Hallucination Scale-Revised (LSHS-R) was completed by 589 undergraduate students, from which high- and low-predisposed groups were drawn. On the ICIM task, participants were asked to identify within-run picture repetitions, requiring them to inhibit memory traces of the same items seen in previous runs.

RESULTS

Compared to the low LSHS-R group, the high LSHS-R group showed significantly increased false alarms on critical "inhibitory" runs (incorrectly identifying previous-run items as within-run repetitions), but no group differences were found in first-run false alarms or in the identification of within-run targets. These results were specific to hallucination predisposition and could not be explained by other schizophrenia-related characteristics.

CONCLUSIONS

Individuals predisposed to hallucinations show subtle, though consistent difficulties with intentional inhibition similar to patients with hallucinations. These findings demonstrate a continuity of cognitive processes in individuals predisposed to hallucinations and in patients with schizophrenia who hallucinate, consistent with a common neurodevelopmental pathway.