Factorial structure of the hallucinatory experience: continuity of experience in psychotic and normal individuals

Sleep spindle activity and psychotic experiences: Examining the mediating roles of attentional performance and perceptual distortions in a daytime nap study

Decreased sleep spindle activity in individuals with psychotic disorders is well studied, but its contribution to psychotic symptom formation is not well understood. This study explored potential underlying mechanisms explaining the association between decreased sleep spindle activity and psychotic symptoms. To this end, we analysed the links between sleep spindle activity and psychotic experiences and probed for the mediating roles of attentional performance and perceptual distortions in a community sample of young adults (N = 70; 26.33 ± 4.84 years). Polysomnography was recorded during a 90-min daytime nap and duration, amplitude, and density from slow (10-13 Hz) and fast (13-16 Hz) spindles were extracted. Attentional performance was assessed via a test battery and with an antisaccadic eye movement task. Psychotic experiences (i.e., paranoid thoughts; hallucinatory experiences) and perceptual distortions (i.e., anomalous perceptions; sensory gating deficits) were assessed via self-report questionnaires. We conducted sequential mediation analyses with spindle activity as predictor, psychotic experiences as dependent variable, and attentional performance and perceptual distortions as mediators. We found reduced right central spindle amplitude to be associated with paranoid thoughts. Increased antisaccadic error rate was associated with anomalous perceptions and perceptual distortions were associated with psychotic experiences. We did not find significant mediation effects. The findings support the notion that reduced sleep spindle activity is involved in the formation of paranoid thoughts and that decreased antisaccadic performance is indicative of perceptual distortions as potential precursors for psychotic experiences. However, further research is needed to corroborate the proposed mediation hypothesis.

Proof-of-concept evidence for high-density EEG investigation of sleep slow wave traveling in First-Episode Psychosis

Schizophrenia is thought to reflect aberrant connectivity within cortico-cortical and reentrant thalamo-cortical loops, which physiologically integrate and coordinate the function of multiple cortical and subcortical structures. Despite extensive research, reliable biomarkers of such "dys-connectivity" remain to be identified at the onset of psychosis, and before exposure to antipsychotic drugs. Because slow waves travel across the brain during sleep, they represent an ideal paradigm to study pathological conditions affecting brain connectivity. Here, we provide proof-of-concept evidence for a novel approach to investigate slow wave traveling properties in First-Episode Psychosis (FEP) with high-density electroencephalography (EEG). Whole-night sleep recordings of 5 drug-naïve FEP and 5 age- and gender-matched healthy control subjects were obtained with a 256-channel EEG system. One patient was re-recorded after 6 months and 3 years of continuous clozapine treatment. Slow wave detection and traveling properties were obtained with an open-source toolbox. Slow wave density and slow wave traveled distance (measured as the line of longest displacement) were significantly lower in patients (p < 0.05). In the patient who was tested longitudinally during effective clozapine treatment, slow wave density normalized, while traveling distance only partially recovered. These preliminary findings suggest that slow wave traveling could be employed in larger samples to detect cortical "dys-connectivity" at psychosis onset.

Measurement invariance between online and paper-and-pencil formats of the Launay-Slade Hallucinations scale-extended (LSHS-E) in the Chilean population: Invariance between LSHS-E formats

Research on the multidimensionality of hallucination-like experiences (HLEs) can contribute to the study of psychotic risk. The Launay-Slade Hallucinations Scale-Extended (LSHS-E) is one of the most widely used tools for research in HLEs, but the correspondence of its paper and online formats has not been established yet. Therefore, we studied the factorial structure and measurement invariance between online and paper-and-pencil versions of LSHS-E in a Chilean population. Two thousand eighty-six completed the online version, and 578 students completed the original paper-and-pencil version. After matching by sex, age, civil status, alcohol and cannabis consumption, and psychiatric treatment received, we selected 543 students from each group. We conducted a confirmatory factor analysis of a four-factor model and a hierarchical model that included a general predisposition to hallucination, explaining the strong relationship between the different types of hallucinations. Both models showed a good fit to the data and were invariant between paper-and-pencil and online versions. Also, the LSHS-E has good reliability in both online and paper-and-pencil formats. This study shows that the online LSHS-E possesses psychometric properties equivalent to the paper-and-pencil version. It should be considered a valuable tool for research of psychosis determinants in the COVID-19 era.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s12144-021-02497-7.

Validation of the Launay-Slade Hallucination Scale among Indian Healthy Adults

Psychotic Like Experiences (PLEs) have been reported in several cultures. The 16 item Launay-Slade Hallucination Scale-Extended (LSHS-E) measures hallucination like experiences (HLEs) in the general population. This study investigated the psychometric properties and the factor structure of LSHS-E Hindi among healthy adults of Delhi. LSHS-E was translated from English to Hindi and then back to English. It was administered as a paper pencil questionnaire to 182 adults from the general population. Reliability of LSHS-E Hindi was measured using Cronbach's alpha and factor structure was established using confirmatory factor analysis (CFA). It was tested against the Community Assessment of Psychic Experiences (CAPE-42) for convergent and divergent validity. Latent Class Analysis (LCA) was performed to identify subgroups with different endorsement of HLEs. Among 182, 18 participants reporting mental and neurological disorders were excluded. LSHS-E Hindi had good reliability (0.85; 95% CI: 0.82 to 0.88). CFA of Hindi LSHS-E revealed the a priori four-factor solution to be best, namely: 'intrusive thoughts', 'vivid daydreams', 'multisensory HLEs', 'auditory and visual HLEs'. LSHS-E Hindi showed stronger correlation with positive domain of CAPE than with negative and depression domains. LCA revealed three classes: low, intermediate and high endorsement of HLEs. Participants with highest endorsement of HLEs were less educated and had highest endorsement on all CAPE dimensions. LSHS-E Hindi has good psychometric properties and can be used to study HLEs in Indians. The four-factor structure model depicts the multidimensionality of HLEs, with 'intrusive thoughts' being the most commonly reported HLE in the sample. LCA supports the continuum hypothesis of HLEs.

The relationship between nightmares and psychotic experiences in young adults

BACKGROUND

There is indication that frequent nightmares are an early indicator of psychotic disorders in adolescents and young adults. Yet which aspects of nightmares are relevant and how they contribute to psychotic experiences has remained unclear.

METHODS

We conducted a cross-sectional online survey in a community sample of young adults between the ages of 18 and 27 (n = 486) to identify aspects of nightmares (nightmare frequency (NF), nightmare distress (ND), nightmare contents), that are related to specific psychotic experiences (paranoid thoughts, hallucinations, negative symptoms) after controlling for sleep quality, and examined factors that potentially mediate this relationship (stress, depression).

RESULTS

Nightmare frequency and -distress were significantly associated with paranoid thoughts, hallucinations and negative symptoms (NF: r_s = 0.293 - 0.139; ND: r_s = 0.411 - 0.166). Nightmares significantly added to explaining paranoid thoughts and hallucinations, over and above sleep quality, but not to explaining negative symptoms. The relations between nightmare distress and psychotic experiences were partially mediated by stress (percentage mediated for paranoid thoughts: 38.20%; for hallucinations: 11.77%) and depression (percentage mediated for paranoid thoughts: 56.61%; for hallucinations: 28.02%). The most commonly reported nightmare contents revolved around being chased, falling and losing a close relative and specific contents were significantly related to the frequency of hallucinations (eg, threatening surroundings, OR = 1.73) or paranoia (eg, workspace bullying, OR = 2.02).

CONCLUSIONS

Thorough assessments of nightmares and sleep disturbances in young individuals could facilitate early detection of those at risk and help to target preventive treatments. However, longitudinal studies are needed to test for a causal relationship between nightmares and the development of psychotic symptoms.

Postural Control and Verbal and Visual Working Memory Correlates in Nonclinical Psychosis

INTRODUCTION

Motor and cognitive abnormalities are well documented in psychosis spectrum disorders. Evidence suggests these deficits could be pronounced because of disruptions in the cerebellar-thalamic-cortical-cerebellar (CTCC) circuit, a network thought to be heavily implicated in motor and higher cognitive functioning. Although significant research has been done on this topic in individuals with schizophrenia and those at a clinical high risk for psychosis, much less is known about deficits at the lower end of the spectrum.

METHODS

In this study, we extended the understanding of motor abnormalities across the psychosis continuum by examining postural sway deficits in the nonclinical psychosis (NCP) population. Furthermore, we linked these deficits to verbal and visual working memory. High-NCP (n = 37) and low-NCP control (n = 31) participants completed an instrumental balance task, highly sensitive to subtle variations in postural sway, along with a brief working memory battery.

RESULTS

We found that high-NCP participants presented with increased postural sway area (i.e., worse postural control) relative to low-NCP controls on a difficult condition (with limited proprioceptive cues), but not on an easier condition. Furthermore, results indicated that the sway area was correlated with poorer performance on working memory tasks in the high-NCP group.

CONCLUSION

These findings suggest that CTCC circuit abnormalities are present across the lower end of the psychosis spectrum and that they may be contributing to a range of motor and cognitive behaviors seen in the population. However, evidence suggests that the signs are subtle, and that sensitive assessment devices and challenging conditions may be necessary for detection.

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.

Measuring fluctuations across the Continuum of Auditory Hallucinations. Development and validation of a state inventory

In order to identify causes and triggers of hallucinations that can inform therapy, reliable, valid, and change-sensitive instruments to assess hallucinatory experiences in the subclinical and clinical range are needed. We developed and validated a novel scale, the Continuum of Auditory Hallucinations - State Assessment (CAHSA), to be used for repeated assessment of the subclinical factors vivid imagination, intrusive thoughts, and perceptual sensitivity as well as auditory hallucinations. After selecting items for the four factors in a first test sample (n=84), we tested factorial validity using CFA and criterion validity with self-reported psychosis-like experiences (n=534). Finally, within-subject variation of CAHSA scores over 14 days and time-lagged associations between its factors were explored (n=85). A 9-item CAHSA was selected that showed good factorial validity, criterion validity, and substantial, valid within-subject variation. Time-lagged regression showed that vivid imagination, perceptual sensitivity, and intrusive thought precede auditory hallucinations. In sum, the CAHSA validly measures fluctuation along the continuum of auditory hallucinations, is sensitive to change, and well suited for experimental studies, repeated measurement, and longitudinal research.

[Factorial Structure of the Cardiff Anomalous Perceptions Scale (CAPS) in a Colombian Population Sample]

BACKGROUND

The continuum hypothesis of psychosis assumes that hallucinations are not exclusive of psychotic disorders. A number of psychometric tests have been developed to assess psychosis using a dimensional model.

OBJECTIVES

To determine the factorial structure of the Cardiff Anomalous Perceptions Scale (CAPS) for the Colombian population, and to contrast the fit of two factor models previously reported in the literature by conducting a confirmatory factor analysis (CFA).

METHODS

This was a cross-sectional study in which 207 subjects from the general population were assessed using the Cardiff Anomalous Perceptions Scale.

RESULTS

A two-factor structure with acceptable ordinal alpha coefficients (α=.88 and α=.87) was found. One factor gathered items related to multimodal perceptual alterations, and a second factor grouped items related with experiences linked to the temporal lobe. The analysis of the first factor indicated that it was dependent on cultural issues for the interpretation of sensations. The second factor appeared almost unchanged on diverse populations, suggesting its transcultural character. When comparing the models proposed by Bell et al. and Jaen-Moreno et al. using the data obtained from the sample, the confirmatory factor analysis conducted indicated inadequate goodness-of-fit indexes (χ(2)). However, some incremental goodness-of-fit indexes (normalized χ(2) [RMSEA]) were acceptable. The Jaén-Moreno et al. model showed the best fit to the data collected from the Colombian sample.

CONCLUSIONS

The factorial structure of CAPS for the Colombian population appears to be sensitive to cultural issues, especially when describing anomalous sensorial experiences.

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.

Stimulating the aberrant brain: Evidence for increased cortical hyperexcitability from a transcranial direct current stimulation (tDCS) study of individuals predisposed to anomalous perceptions

Findings from neurological and clinical groups have shown that increased predisposition to anomalous experience/aura reflects an elevation in aberrant neural processes in the brain. However, studies of anomalous experiences in non-clinical/non-neurological groups are less clear on this matter and are more typically confined to subjective questionnaire measures alone. The current investigation, the first to our knowledge, carried out a transcranial Direct Current Stimulation (tDCS) study of cortical hyperexcitability, and its association with anomalous experience in non-clinical/non-neurological groups. Sixty participants completed; (i) both excitatory (anodal) and inhibitory (cathodal) brain stimulation conditions of the visual cortex; (ii) a computerised pattern-glare task, where observers reported phantom visual distortions from viewing highly irritable visual patterns (a metric of cortical hyperexcitability), and; (iii) questionnaire measures of predisposition to anomalous perceptions. There were no reliable signs of cortical hyperexcitability (via pattern-glare tasks) when collapsed across the whole sample. However, a significant positive correlation between predisposition to anomalous experience and elevated signs of cortical hyperexcitability was observed. Crucially, there was a significant negative correlation between tDCS stimulatory conditions. A visual cortex that reacted more strongly to excitatory stimulation, responded less well to inhibitory suppression, and this pattern was related to predisposition to anomalous perceptions. Both findings are consistent with the presence of a hyperexcitable cortex. Collectively the present findings provide objective evidence that the brains of individuals predisposed to anomalous experiences/hallucinations can be hyperexcitable - even in the non-clinical/non-neurological population. These data are consistent with continuum models of anomalous experience and have important implications for contemporary theories of aberrations in self-consciousness.

Epistemological implications of near-death experiences and other non-ordinary mental expressions: Moving beyond the concept of altered state of consciousness

During the last decades an increasing interest has developed in the so-called altered state of consciousness (ASCs); among these, near-death experiences (NDEs) are one of the most intriguing and debated examples. NDEs are deep and universal experiences with a clear phenomenology and incidence, while some of their features challenge the current views of human consciousness (focused on neural circuits and based on the concept of mind as a byproduct of brain circuitry) with relevant epistemological and historical implications. The origin of the ruling mechanist-reductionist paradigm can be traced back to Descartes' radical separation of res cogitans and res extensa and the conflict between the nascent science and the Inquisition; this led to removing the subjective properties of mind from the field of scientific interest, relegating them to philosophy and theology in order to enable the development of modern science. However, the physics of the 20th century has eventually moved beyond the classical paradigm, permitting a profound renewal of scientific interest in the mind. Modern research on NDEs has contributed to reopening the debate surrounding the Cartesian separation, the mind-brain relationship and the nature of consciousness. It is now time to reappraise the relevance, strengths, and weaknesses of the available scientific interpretations of NDEs, their relationship with other ASCs, as well as the very concept of ASC; the latter looks to be ill-founded, suggesting the need for: (a) a revision of the conventional approach to subjective phenomena, including both the third- and first-person perspective; and (b) a deep reflection on the possible links between different non-ordinary mental expression, as regards both their phenomenology and mechanisms from a non-pathological perspective.

Differences in the internal structure of hallucinatory experiences between clinical and nonclinical populations

We investigated differential patterns of hallucinatory experiences between nonclinical and clinical samples. A total of 223 nonclinical individuals (108 females) and 111 subjects with schizophrenia (54 females) completed the Launay-Slade Hallucination Scale-Revised (LSHS-R) and Perceptual Aberration Scale (PAS). The Minnesota Multiphasic Personality Inventory-2 (MMPI-2) was used for the nonclinical group, and the Positive and Negative Syndrome Scale (PANSS) hallucination item was used for the clinical group. Cronbach's alpha values showed good internal consistency for the LSHS-R. In the two groups, significant associations were found between LSHS-R and PAS scores. Two factors were extracted through a principal component analysis (PCA) in the nonclinical group, and three factors were identified in the clinical group. The results of a hierarchical cluster analysis (HCA) revealed that a perception-cognition dimension was clear cluster discriminating element for the nonclinical group, whereas alterations in perception-cognition dimension were characteristic in cluster structure of the clinical group. Our findings suggest that the nature of hallucinatory experiences may differ qualitatively between a nonclinical population and subjects with schizophrenia. Perceptual or cognitive aberrations may add a psychopathologic dimension to hallucinatory experiences. Exploring the internal structure of hallucinatory experiences may provide explanatory insight into these experiences in the general population.

Voice identity discrimination and hallucination-proneness in healthy young adults: a further challenge to the continuum model of psychosis?

INTRODUCTION

Auditory hallucinations occur in schizophrenia and also in the general population. However, evidence points to differences in the nature and the mechanisms of clinical and non-clinical hallucinations, challenging the dominant assumption that they represent the same phenomenon. The current study extended this evidence by examining voice identity perception in hallucination-prone individuals. In schizophrenia, deficiencies discriminating between real (external) voices have been linked to basic acoustic cues, but voice discrimination has not yet been investigated in non-clinical hallucinations.

METHODS

Using a task identical to that employed in patients, multidimensional scaling of voice dissimilarity judgements was used to examine how healthy individuals differing in hallucination-proneness (30 high and 30 low hallucination-prone individuals) distinguish pairs of unfamiliar voices. The resulting dimensions were interpreted with reference to acoustic measures relevant to voice identity.

RESULTS

A two-dimensional "voice space", defined by fundamental frequency (F0) and formant dispersion (Df), was derived for high and low hallucination-prone groups. There were no significant differences in speaker discrimination for high versus low hallucination-prone individuals on the basis of either F0 or Df.

CONCLUSIONS

These findings suggest voice identity perception is not impaired in healthy individuals predisposed to hallucinations, adding a further challenge to the continuum model of psychotic symptoms.

The influence of hallucination proneness and social threat on time perception

INTRODUCTION

Individuals with schizophrenia frequently report disturbances in time perception, but the precise nature of such deficits and their relation to specific symptoms of the disorder is unclear. We sought to determine the relationship between hallucination proneness and time perception in healthy individuals, and whether this relationship is moderated by hypervigilance to threat-related stimuli.

METHODS

206 participants completed the Revised Launay-Slade Hallucination Scale (LSHS-R) and a time reproduction task in which, on each trial, participants viewed a face (happy, angry, neutral, or fearful) for between 1 and 5 s and then reproduced the time period with a spacebar press.

RESULTS

High LSHS-R scores were associated with longer time estimates, but only during exposure to angry faces. A factor analysis of LSHS-R scores identified a factor comprising items related to reality monitoring, and this factor was most associated with the longer time estimates.

CONCLUSIONS

During exposure to potential threat in the environment, duration estimates increase with hallucination proneness. The experience of feeling exposed to threat for longer may serve to maintain a state of hypervigilance which has been shown previously to be associated with positive symptoms of schizophrenia.

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.

Externalizing biases and hallucinations in source-monitoring, self-monitoring and signal detection studies: a meta-analytic review

BACKGROUND

Cognitive models have postulated that auditory hallucinations arise from the misattribution of internally generated cognitive events to external sources. Several experimental paradigms have been developed to assess this externalizing bias in clinical and non-clinical hallucination-prone samples, including source-monitoring, verbal self-monitoring and auditory signal detection tasks. This meta-analysis aims to synthesize the wealth of empirical findings from these experimental studies.

METHOD

A database search was carried out for reports between January 1985 and March 2012. Additional studies were retrieved by contacting authors and screening references of eligible reports. Studies were considered eligible if they compared either (i) hallucinating and non-hallucinating patients with comparable diagnoses, or (ii) non-clinical hallucination-prone and non-prone participants using source-monitoring, verbal self-monitoring or signal detection tasks, or used correlational analyses to estimate comparable effects.

RESULTS

The analysis included 15 clinical (240 hallucinating patients and 249 non-hallucinating patients) and nine non-clinical studies (171 hallucination-prone and 177 non-prone participants; 57 participants in a correlation study). Moderate-to-large summary effects were observed in both the clinical and analogue samples. Robust and significant effects were observed in source-monitoring and signal detection studies, but not in self-monitoring studies, possibly due to the small numbers of eligible studies in this subgroup. The use of emotionally valenced stimuli led to effects of similar magnitude to the use of neutral stimuli.

CONCLUSIONS

The findings suggest that externalizing biases are important cognitive underpinnings of hallucinatory experiences. Clinical interventions targeting these biases should be explored as possible treatments for clients with distressing voices.

Emotion recognition and social/role dysfunction in non-clinical psychosis

As researchers continue to understand non-clinical psychosis (NCP-brief psychotic-like experiences occurring in 5-7% of the general population; van Os et al., 2009), it is becoming evident that functioning deficits and facial emotion recognition (FER) impairment characterize this phenomenon. However, the extent to which these domains are related remains unclear. Social/role functioning and FER were assessed in 65 adolescents/young adults exhibiting low and high-NCP. Results indicate that FER and social/role functioning deficits were present in the High-NCP group, and that the domains were associated in this group alone. Taken together, findings suggest that a core emotive deficit is tied to broader social/role dysfunction in NCP.

Heritability of hallucinations in adolescent twins

Hallucinations are common in normal individuals and patients with schizophrenia and other psychotic disorders. Traditionally psycho-social approaches have emphasized the importance of environmental factors that contribute to variation of hallucinations. Using the Launay-Slade Hallucination Scale-Revised (LSHS-R), we investigated genetic and environmental influences on hallucinations in 598 pairs of healthy South Korean adolescent twins. Parameter estimates in the best-fitting model indicated that additive genetic and individual specific environmental factors for the LSHS-R were 33% (95% CI: 23-42%) and 67% (95% CI: 60-77%), respectively. There was no evidence for sex-specific genes for hallucinations. The magnitudes of genetic and environmental influences on hallucinations were similar in males and females. These results have implications in future molecular genetic studies that search for genes for hallucinations.

BDNF Val66Met and spontaneous dyskinesias in non-clinical psychosis

BACKGROUND

Evidence indicating that symptoms of non-clinical psychosis (NCP) occur in 6-8% of the general population suggests that psychosis may occur across a continuum. Although a number of studies have examined environmental contributors, to date there have been few investigations of biological/genetic factors in this integral population. A recent study observed spontaneous dyskinetic movements (reflecting an innervated striatal system) in individuals reporting NCP. The present investigation is designed to replicate this finding and determine if brain-derived neurotrophic factor (BDNF) (implicated in striatal dopamine function) is associated with dyskinesias.

METHOD

A total of 68 young-adult participants reporting High and Low-NCP were assessed for dyskinetic movements using a sensitive instrumental measure of force variability. Saliva from the participants was genotyped for val66met (rs6265), a common functional polymorphism of the BDNF gene (the Met allele is associated with lower activity-dependent release of BDNF).

RESULTS

Participants in the High-NCP group showed significantly elevated levels of force variability. Met allele carriers exhibited significantly higher levels of force variability when compared with the Val homozygotes. Logistic regression indicated that the odds of membership in the High-NCP group were significantly higher given the presence of dyskinesias (OR=2.32; CI: 1.25-4.28).

CONCLUSION

Findings of elevated force variability suggest that individuals with NCP exhibit subtle signs of striatal vulnerability, reflected more dramatically as jerking and hyperkinetic movements in patients with formal psychosis. The results are consistent with a larger literature implicating BDNF as a critical factor underlying abnormal movements, and suggest that specific candidate genes underlie putative markers across a psychosis continuum.

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.

Mindfulness-Based Intervention on Distressing Hallucination-Like Experiences in a Nonclinical Sample

The presence of psychotic-like experiences in the general population has been amply reported. Nevertheless, the degree of concern or anxiety that such experiences may generate is an aspect that has not received as much appraisal. In this sense, mindfulness is an approach to intervention based on the modification of the individual's relationship with the symptoms, instead of their elimination. The goal of the present study is to compare the effect of mindfulness training on distressing hallucination-like experiences. Eighteen participants were assigned to the experimental group, and they received 8 sessions of mindfulness training; 20 participants were assigned to a control group that viewed 8 sessions of a video forum. The results showed that upon completing the mindfulness training, there was a significant and large effect on the decrease of anxiety caused by hallucination-like experiences. These results were maintained at the 16-week follow-up. The repercussions of these results are underlined.

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.

Borderline personality traits in nonclinical young adults

The main purpose of this study was to explore the dimensionality of the borderline personality disorder in nonclinical young adults by means of the Borderline Personality Questionnaire (BPQ; Poreh et al., 2006). We also studied the phenotypic expression of the borderline personality traits as a function of participants' gender and age, and the relationship between BPQ subscales and measures of depressive symptoms, anxiety, stress, hallucinatory predisposition, and paranoid ideation. The sample comprised 809 young adults, 562 (69.5%) were women, with a mean age of 20.2 years (SD = 2.9). The results indicate that the BPQ self-report has adequate psychometric properties. The levels of internal consistency for the BPQ subscales ranged between .78 and .93. Analysis of the internal structure of the BPQ subscales yielded a one-dimensional solution. In contrast, second-order principal components analysis at the item level yielded a five-dimensional solution. Likewise, statistically significant differences in the mean scores of the borderline personality traits as a function of participants' gender and age were found. The BPQ subscales correlated significantly with measures of depression, anxiety, stress, paranoid ideation, and hallucinatory predisposition. These results help to improve our understanding of the dimensional structure of the borderline personality in the general population. Future research should continue to identify participants who are at risk for the development of borderline personality disorder and facilitating the development of early detection and prevention programs.

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.

Cognitive and meta-cognitive dimensions of psychoses

This paper outlines cognitive approaches to understanding and treating positive psychotic symptoms, such as hallucinations, delusions, and dissociations. Recent cognitive accounts of psychosis are reviewed along with the claim that it is not the symptoms themselves but cognitive and meta-cognitive appraisals (attributions and beliefs) about the significance of the symptoms that cause distress and dysfunction. Psychotic symptoms do lie on a continuum with normal experience. Cognitive appraisal dimensions may interact with reasoning styles such as inferential confusion, cognitive slippage, fantasy proneness, and perceptual immersion (styles also normally distributed in the population) and together persuade the person with psychosis to live in fictional narratives as if they were real. Recent clinical studies suggest that addressing beliefs about symptoms modifying inferential styles and normalizing experiences may help symptom management.

A systematic review and meta-analysis of the psychosis continuum: evidence for a psychosis proneness-persistence-impairment model of psychotic disorder

A systematic review of all reported incidence and prevalence studies of population rates of subclinical psychotic experiences reveals a median prevalence rate of around 5% and a median incidence rate of around 3%. A meta-analysis of risk factors reveals associations with developmental stage, child and adult social adversity, psychoactive drug use, and also male sex and migrant status. The small difference between prevalence and incidence rates, together with data from follow-up studies, indicates that approximately 75-90% of developmental psychotic experiences are transitory and disappear over time. There is evidence, however, that transitory developmental expression of psychosis (psychosis proneness) may become abnormally persistent (persistence) and subsequently clinically relevant (impairment), depending on the degree of environmental risk the person is additionally exposed to. The psychosis proneness-persistence-impairment model considers genetic background factors impacting on a broadly distributed and transitory population expression of psychosis during development, poor prognosis of which, in terms of persistence and clinical need, is predicted by environmental exposure interacting with genetic risk.

Visual hallucinations in consultation-liaison neuropsychiatry

BACKGROUND

In consultation-liaison settings, neuropsychiatrists are commonly asked to assess patients with hallucinatory syndromes and to differentiate 'functional' from 'organic' psychotic presentations.

METHODS

The occurrence and management of visual hallucinations (VH) in healthy individuals, lesion states, neurodegenerative disorders, intoxication/withdrawal states and delirium are reviewed.

RESULTS

The presence of VH has been shown to predict a secondary rather than primary psychotic illness and an understanding of the neurobiology of the visual system - including how and where underlying neurotransmitter systems interact in visual processing and how perturbations can result in VH - allows for appropriate clinical assessment and management.

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.

Boundaries of mental disorders

PURPOSE OF REVIEW

This article reviews the problem of 'boundaries' in psychopathology and its conceptualization in the diagnostic classification of psychiatric disorders.

RECENT FINDINGS

A modest number of publications in 2004-2005 contribute concepts, methods and data relevant to several aspects of the problem: scientific 'facts' versus value attribution in the definition of mental disorders; the problem of comorbidity between diagnostic entities; the spurious dichotomy between categorical versus dimensional approaches to diagnosis and classification; and the distinction between validity and pragmatic utility.

SUMMARY

The relative paucity of research explicitly addressing these issues should be a reason for concern in the debate leading up to the next revisions of the International Classification of Diseases and the Diagnostic and Statistical Manual of Mental Disorders.