Prevalence and classification of hallucinations in multiple sensory modalities in schizophrenia spectrum disorders

Empathy Amplified: Exploring the Transformative Potential of Understanding Auditory Hallucinations Through Staff Training

BACKGROUND

Stigmatization of individuals diagnosed with psychosis, especially those who experience auditory hallucinations, is a well-documented issue with negative outcomes on provision of care. Existing research has predominantly concentrated on experiential training for students, leaving a significant gap in knowledge regarding the training's impact on practicing psychiatric nurses and technicians.

AIMS

This study aims to address this gap by investigating the efficacy of a concise, 1-hour educational activity designed to improve empathy, confidence, competence, and knowledge in psychiatric professionals.

METHODS

Participants engaged in a 1-hour training session that included simulated activities while listening to distressing voices and completed pretraining and posttraining assessments.

RESULTS

Results demonstrated a notable increase in empathy toward individuals who hear voices, suggesting that the training had a positive effect. Furthermore, significant differences were observed in the participants' perceptions of the level of difficulty as well as increased levels of confidence and perceived competence in their ability to provide care.

CONCLUSIONS

The results underscore the practicality and effectiveness of brief hearing voices simulations as a means to enhance the skills of existing health care providers. This approach allows professionals to better express empathy and gain a deeper understanding of the experiences of voice hearers.

Progressive loss of cortical gray matter in first episode psychosis patients with auditory hallucinations

BACKGROUND

Previous longitudinal magnetic resonance imaging studies have shown progressive gray matter (GM) reduction during the earliest phases of schizophrenia. It is unknown whether these progressive processes are homogeneous in all groups of patients. One way to obtain more valid findings is to focus on the symptoms. Auditory hallucinations (AHs) are frequent and reliable symptoms of psychosis. The present study aims to analyze whether longitudinal changes in structural abnormalities in cortical regions are related to the presence of AHs and the intensity of psychotic symptoms in a large sample.

METHODS

A Magnetic Resonance (MR) voxel-based morphometry analysis was applied to a group of 128 first episodes psychosis (FEP) patients (63 patients with AHs and 65 patients without AHs) and 78 matched healthy controls at baseline and at a 2-year follow-up.

RESULTS

At baseline, FEP patients exhibited significant GM volume reductions in the temporal, frontal and precentral regions. At follow-up, FEP patients exhibited GM volume changes in the temporal, Rolandic, frontal, precentral and insula regions. At baseline, no significant differences were found between FEP patients with and without AHs. At follow-up, while FEP patients with AHs showed less GM volume in temporal and frontal lobes, non-AH FEP patients showed reductions in the frontal, precentral and fusiform areas. PANSS scores showed statistically significant correlations with GM volume reductions at baseline and follow-up.

CONCLUSIONS

Brain cortical loss in the early phases of psychosis is not associated with potentially transitory AHs; however, brain structural changes may emerge as AHs appear in chronic patients.

The Phenomenology of Visual and Other Nonauditory Hallucinations in Affective and Nonaffective Psychosis: A Mixed Methods Analysis

ABSTRACT

Nonauditory hallucinations in psychosis have not received as much attention relative to voice-hearing experiences. The current paper aimed to document the characteristics of these hallucinations in affective and nonaffective psychosis. Participants were selected from a primary voice-hearing sample, who had endorsed visual, tactile, or olfactory hallucinations ( N = 55-75). A comprehensive, semistructured phenomenological interview was conducted, followed by mixed methods analysis. Visual hallucinations typically occurred daily, for a few minutes per episode, within one's direct line of sight; persons and/or animals were most commonly seen, with low controllability and mostly engendered negative affective outcomes. Tactile and olfactory hallucinations were endorsed by 46.8% and 39.0% of participants, respectively. The affective psychosis group ( n = 33) reported significantly greater awareness and lower functional impairment relative to the nonaffective psychosis group ( n = 42). Qualitative thematic analysis revealed notable themes and subthemes across each of these hallucinations modes. Further phenomenological investigations should be carried out in lesser known hallucination modalities, assisted by the development of appropriate assessment tools.

Carl Jung: a life on the edge of reality with hypnagogia, hyperphantasia, and hallucinations

Whether the Swiss psychiatrist Carl Jung (1875-1961) became psychotic after his mid-thirties is much debated. His recently published Black Books, a seven-volume journal, reveal new insights into this debate. Based on a phenomenological analysis of his self-reports in these books and in other writings, we here identify several types of anomalous perceptual experiences: hypnagogic-hypnopompic experiences, hyperphantasia, hallucinations, personifications, and sensed presence. We argue that these experiences were not indicative of a psychotic disorder, but rather stemmed from extremely vivid mental imagery, or hyperphantasia, a condition Jung's contemporaries and later biographers were unable to take into account because it had not yet been conceptualised. Recently, the degree of vividness of mental imagery and its potential to become indistinguishable from regular sense perception has been the subject of extensive studies. Unknowingly, Jung may have foreshadowed this line of research with his psychoanalytic concept of reality equivalence, i.e., the substitution of an external world for an inner mental reality that he encountered in individuals diagnosed with schizophrenia. There is a need for future research to investigate the possible role of hyperphantasia in psychotic experiences, but to Jung, psychosis was 'a failure to contain and comprehend' the content of one's experiences in the context of one's own life, whereas he himself did manage to put the content of his perceptual experiences into context, to find meaning in them, and to share them with others - to great acknowledgement and acclaim.

Multi-modal hallucinations across diagnoses: What relationships do they have with voice-related distress?

BACKGROUND

Research into hallucinatory experiences has focused primarily upon hallucinations within the auditory modality, to the relative neglect of other modalities. Furthermore, the exploration of auditory hallucinations (or 'voices') has focused primarily upon the experiences of people with a diagnosis of psychosis. The presence of multi-modal hallucinations may have implications across diagnoses for levels of distress, formulation and the targeting of psychological interventions.

METHODS

This study presents a cross-sectional analysis of observational data from the PREFER survey (N = 335). Linear regression was used to explore the relationships between voice-related distress and the presence, number, type and timing of multi-modal hallucinations.

RESULTS

Simple relationships were not found between distress and the presence of hallucinations in visual, tactile, olfactory or gustatory modalities, or in the number of modalities experienced. When considering the degree to which another modality hallucination was experienced simultaneously with voices, there was some evidence that the degree of co-occurrence with visual hallucinations was predictive of distress.

CONCLUSIONS

The co-occurrence of voices with visual hallucinations may be associated with relatively greater distress, but not consistently, and the association between multimodal hallucinations and clinical impact appear complex and potentially variable from individual to individual. Further study of associated variables such as perceived voice power may further illuminate these relationships.

Psychotic Symptoms in Patients With Major Neurological Diseases

Neurological diseases often manifest with neuropsychiatric symptoms such as depression, emotional incontinence, anger, apathy and fatigue. In addition, affected patients may also experience psychotic symptoms such as hallucinations and delusions. Various factors contribute to the development of psychotic symptoms, and the mechanisms of psychosis are similar, but still differ among various neurological diseases. Although psychotic symptoms are uncommon, and have been less well investigated, they may annoy patients and their families as well as impair the patients' quality of life and increase the caregiver burden. Therefore, we need to appropriately identify and treat these psychotic symptoms in patients with neurological diseases.

Non-clinical hallucinations and mental imagery across sensory modalities

INTRODUCTION

Vivid mental imagery has been proposed to increase the likelihood of experiencing hallucinations. Typically, studies have employed a modality general approach to mental imagery which compares imagery across multiple domains (e.g., visual, auditory and tactile) to hallucinations in multiple senses. However, modality specific imagery may be a better predictor of hallucinations in the same domain. The study examined the contribution of imagery to hallucinations in a non-clinical sample and specifically whether imagery best predicted hallucinations at a modality general or modality specific level.

METHODS

In study one, modality general and modality specific accounts of the imagery-hallucination relationship were contrasted through application of self-report measures in a sample of 434 students. Study two used a subsample (n = 103) to extend exploration of the imagery-hallucinations relationship using a performance-based imagery task.

RESULTS

A small to moderate modality general relationship was observed between self-report imagery and hallucination proneness. There was only evidence of a modality specific relationship in the tactile domain. Performance-based imagery measures were unrelated to hallucinations and self-report imagery.

CONCLUSIONS

Mental imagery may act as a modality general process increasing hallucination proneness. The observed distinction between self-report and performance-based imagery highlights the difficulty of accurately measuring internal processes.

Exploring the cognitive profiles related to unimodal auditory versus multisensory hallucinations in schizophrenia-spectrum disorders

INTRODUCTION

Hallucinations can be experienced across multiple sensory modalities, but psychiatric studies investigating the cognitive mechanisms of hallucinations have been somewhat restricted to the auditory domain. This study explored the cognitive profiles of individuals experiencing multisensory hallucinations (MH) in schizophrenia-spectrum disorders (SSD) and compared these to those experiencing unimodal auditory hallucinations (AH) or no hallucinations (NH).

METHODS

Participants included SSD patients (n = 119) stratified by current hallucination status (NH, AH, MH) and nonclinical controls (NCs; n = 113). Group performance was compared across several cognitive domains: speed of processing, attention, working memory, verbal learning, visual learning, reasoning and problem-solving, social cognition, and inhibition.

RESULTS

The clinical groups performed worse than NCs but differences between the clinical groups were not evident across most cognitive domains. Exploratory analyses revealed that the MH group was more impaired on the visual learning task compared to the NH (but not AH) group.

CONCLUSIONS

Preliminary results suggest that impaired visual learning may be related to MH. This could be attributed to the presence of visual hallucinations (VH), or greater psychopathology, in this group. However, replication is needed, as well as the investigation of other potential cognitive mechanisms of MH.

A comprehensive update on genetic inheritance, epigenetic factors, associated pathology, and recent therapeutic intervention by gene therapy in schizophrenia

Schizophrenia is a severe psychological disorder in which reality is interpreted abnormally by the patient. The symptoms of the disease include delusions and hallucinations, associated with extremely disordered behavior and thinking, which may affect the daily lives of the patients. Advancements in technology have led to understanding the dynamics of the disease and the identification of the underlying causes. Multiple investigations prove that it is regulated genetically, and epigenetically, and is affected by environmental factors. The molecular and neural pathways linked to the regulation of schizophrenia have been extensively studied. Over 180 Schizophrenic risk loci have now been recognized due to several genome-wide association studies (GWAS). It has been observed that multiple transcription factors (TF) binding-disrupting single nucleotide polymorphisms (SNPs) have been related to gene expression responsible for the disease in cerebral complexes. Copy number variation, SNP defects, and epigenetic changes in chromosomes may cause overexpression or underexpression of certain genes responsible for the disease. Nowadays, gene therapy is being implemented for its treatment as several of these genetic defects have been identified. Scientists are trying to use viral vectors, miRNA, siRNA, and CRISPR technology. In addition, nanotechnology is also being applied to target such genes. The primary aim of such targeting was to either delete or silence such hyperactive genes or induce certain genes that inhibit the expression of these genes. There are challenges in delivering the gene/DNA to the site of action in the brain, and scientists are working to resolve the same. The present article describes the basics regarding the disease, its causes and factors responsible, and the gene therapy solutions available to treat this disease.

The Diagnostic Spectrum of Sexual Hallucinations

ABSTRACT

Sexual hallucinations are little known, yet often extremely burdening, phenomena. In this systematic review, we summarize what is known about their phenomenology, prevalence, etiopathology, ensuing distress, and treatment options. Sexual hallucinations can be experienced as genital or orgasmic sensations, although other sensory modalities can also be involved. With the notable exception of orgasmic auras in the context of epilepsy, sexual hallucinations tend to be distressing and embarrassing in nature. Our analysis of 79 studies (together describing 390 patients) indicates that sexual hallucinations are more frequent in women than in men, with a sex ratio of 1.4:1, and that they are most prevalent in schizophrenia spectrum disorders, with rates ranging from 1.4% in recently admitted patients to 44% in chronically hospitalized patients. Other underlying conditions include epilepsy, the incubus phenomenon (possibly the most prevalent cause in the general population, associated with sleep paralysis), narcolepsy, and sedative use. As regards the sedative context, we found more medicolegal than purely medical cases, which sadly underlines that not all sexually explicit sensations experienced in anesthesia practice are indeed hallucinations. In the absence of evidence-based treatment protocols for sexual hallucinations, practice-based guidelines tend to focus on the underlying condition. Further research is needed, especially in the fields of substance abuse, posttraumatic stress disorder, and borderline personality disorder, where only anecdotal information on sexual hallucinations is available. Moreover, awareness of sexual hallucinations among health professionals needs to be improved in order to facilitate counseling, diagnosis, and treatment.

Pathways from trauma to unusual perceptual experiences: Modelling the roles of insecure attachment, negative affect, emotion regulation and dissociation

BACKGROUND

A range of traumas have been linked to voices (auditory verbal hallucinations) and unusual perceptual experiences (UPEs) in other perceptual-sensory domains. Models of PTSD and positive symptoms of psychosis are insufficient in explaining the relationship between trauma and voices. The trauma-related voices (TRV) model was developed to generate novel research in this area.

AIMS

This study aimed to investigate pathways from trauma to the frequency of UPEs based on a subset of hypothesised relationships in the TRV model.

MATERIALS

The PTSD Diagnostic Scale for DSM-5, State Adult Attachment Measure, Depression Anxiety and Stress Scales-21, Perth Emotion and Regulation Competency Inventory, Dissociative Experiences Measure Oxford, and Multi-modality Unusual Perceptual Experiences Questionnaire.

METHODS

We used path analysis in a non-clinical sample (N = 528) to model indirect effects from diverse trauma experiences to the frequency of multi-sensory UPEs via a subset of mediators within the TRV model: insecure attachment, emotion regulation deficits, negative affect and dissociation.

RESULTS

Our model was an excellent fit to the data and accounted for 37.1% of variance in UPE frequency, and all direct (βs = .14-.61) and indirect pathways (βs = .01-.08) were significant (ps < .001).

DISCUSSION

Our findings suggest that insecure attachment may link diverse trauma experiences to emotion regulation deficits and negative affect, which are linked to UPE frequency via dissociation.

CONCLUSION

Our findings provide preliminary evidence for a subset of relationships within the TRV model. Future studies are needed to gather stronger evidence of temporality and causation between these factors, and to test broader pathways within the TRV model.

Predictors of paranoia in the daily lives of people with non-affective psychosis and non-clinical controls: A systematic review of intensive longitudinal studies

BACKGROUND AND OBJECTIVES

Worrying, self-esteem, sleep problems, anomalous internal experiences, reasoning biases, and interpersonal sensitivity are associated with paranoia. However, no review has examined whether these variables function as predictors of paranoia in everyday life. The present systematic review of intensive longitudinal studies (e.g., experience sampling) examined contemporaneous and time-lagged associations between paranoia and each candidate mechanism in individuals with non-affective psychosis and controls (pre-registration: https://osf.io/uwr9d).

METHODS

We searched electronic databases, PsyArXiv, and reference lists for studies published since 1994.

RESULTS

Of n = 5,918 results, n = 54 fulfilled inclusion criteria (n = 43 datasets). Most studies examined individuals with non-affective psychosis (n = 34). Strong evidence emerged for negative affect (subsumed under 'anomalous internal experiences') and sleep problems. For self-esteem, results suggest contemporaneous and lagged effects on paranoia but associations are likely driven by between-person variance. The low number of studies (n = 2 studies each) allowed no conclusions regarding worrying and reasoning biases. Findings on interpersonal sensitivity, which should be interpreted with caution because of the predictor's conceptual overlap with paranoia, indicate contemporaneous effects whereas time-lagged and within-person associations could not be judged due to insufficient data.

LIMITATIONS

The present review used a narrative data-synthetization and it did not cover outcomes such as hallucinations.

CONCLUSIONS

Despite convincing evidence for affect and sleep problems, it remains unclear whether affective states are precursors or also consequences of paranoia (vicious circle), and which of the actigraphy measures (sleep time, -efficiency, -fragmentation, etc.) best predicts paranoia.

Enhancing Predictive Power: Integrating a Linear Support Vector Classifier with Logistic Regression for Patient Outcome Prognosis in Virtual Reality Therapy for Treatment-Resistant Schizophrenia

(1) Background: Approximately 30% of schizophrenia patients are known to be treatment-resistant. For these cases, more personalized approaches must be developed. Virtual reality therapeutic approaches such as avatar therapy (AT) are currently undergoing investigations to address these patients' needs. To further tailor the therapeutic trajectory of patients presenting with this complex presentation of schizophrenia, quantitative insight about the therapeutic process is warranted. The aim of the study is to combine a classification model with a regression model with the aim of predicting the therapeutic outcomes of patients based on the interactions taking place during their first immersive session of virtual reality therapy. (2) Methods: A combination of a Linear Support Vector Classifier and logistic regression was conducted over a dataset comprising 162 verbatims of the immersive sessions of 18 patients who previously underwent AT. As a testing dataset, 17 participants, unknown to the dataset, had their first immersive session presented to the combinatory model to predict their clinical outcome. (3) Results: The model accurately predicted the clinical outcome for 15 out of the 17 participants. Classification of the therapeutic interactions achieved an accuracy of 63%. (4) Conclusion: To our knowledge, this is the first attempt to predict the outcome of psychotherapy patients based on the content of their interactions with their therapist. These results are important as they open the door to personalization of psychotherapy based on quantitative information about the interactions taking place during AT.

Self-dehumanisation in voice hearers: the end of a continuum

Background

Meta-dehumanisation and self-dehumanisation have been identified as potentially relevant phenomena for developing a deeper understanding of distress related to voice-hearing, particularly those experiencing voices as part of psychosis. Chadwick has previously argued that those with psychosis, including those who hear distressing voices, typically feel "dehumanised and set apart by their experiences of psychosis and trauma." The present study explores the subjective experience of self-dehumanisation in people who experience distressing voices, which was selected as a useful starting point to inform future research focused on understanding dehumanisation in people with psychosis.

Methods

Qualitative data was obtained through twenty semi-structured interviews with self-identifying voice hearers and analysed using reflexive thematic analysis. This followed the recursive six phase procedure of Braun and Clarke, and this was conducted from a critical realist, contextualist position.

Results

Reflexive thematic analysis of participant's experiences produced a core theme, Dehumanisation as the End of Experiential Continua, and six subthemes: Extent of Distressing Sensory Fragmentation; Sense of Belonging with Other Humans; Integrity of Self as a Private, Coherent Entity; Sense of Worth as a Human Being; Strength of Personal Agency; and Trust in Own Credibility and Reliability. Two further themes, The Push and Pull of Dehumanising Forces and Reclaiming Life through Humanising Forces, were identified. Findings were presented to a panel of five experts by experience, all with lived experience of psychosis and service-use; all five strongly endorsed the themes as fitting with and expressing their own experiences of self-dehumanisation.

Conclusion

Reflexive thematic analysis of voice hearers' accounts identified self-dehumanisation as the endpoint where six experiential continua coalesce. Experiential movement along these continua was affected by a range of interpersonal, intrapersonal, and societal forces over time, including dehumanising attitudes of others and voice malevolence and omnipotence. Future research might examine if and how psychological therapies aimed at those experiencing distressing voices, such as people experiencing psychosis may address feelings of self-dehumanisation.

Case report: Impact of hyperthyroidism on psychotic symptoms in schizophrenia comorbid with Graves' disease

Introduction

Auditory hallucinations are the most common type of hallucinations observed in schizophrenia; however, visual hallucinations are not uncommon. In Graves' disease, depression, hypomania, and psychosis can occur. While the association between Graves' disease and psychosis has been explored, understanding of the specific impact of thyroid dysfunction severity on psychiatric symptom severity is limited. Here, we present a case report of a patient with schizophrenia comorbid with Graves' disease whose psychotic symptoms were impacted by hyperthyroidism.

Case

The patient was a 32-year-old Japanese woman who presented with auditory and visual hallucinations, agitation, and pressured speech. The patient was diagnosed with schizophrenia comorbid with Graves' disease and thyroid storm. The patient's psychotic symptoms were found to be associated with fluctuations in thyroid hormone levels, and visual hallucinations were observed only during thyroid storms. Treatment involved dexamethasone, potassium iodide, bisoprolol fumarate, and methimazole for thyrotoxicosis, and a blonanserin transdermal patch, paliperidone, and paliperidone palmitate for psychotic symptoms. The patient's auditory and visual hallucinations improved with antipsychotic treatment and decreased thyroid hormone levels.

Conclusion

This case highlights the importance of monitoring thyroid function in patients with schizophrenia, particularly those with comorbid Graves' disease. The correlation between psychiatric symptoms and thyroid hormone levels was demonstrated on an individual level over time, with symptoms worsening as thyroid hormone levels increased. Additionally, our case suggests that abnormally high thyroid hormone levels may trigger visual hallucinations in individuals with schizophrenia. Further studies are needed to elucidate the underlying mechanisms and potential treatment implications of this association.

Relationship between function and structure in the visual cortex in healthy individuals and in patients with severe mental disorders

Patients with schizophrenia spectrum disorders (SCZ_spect) and bipolar disorders (BD) show impaired function in the primary visual cortex (V1), indicated by altered visual evoked potential (VEP). While the neural substrate for altered VEP in these patients remains elusive, altered V1 structure may play a role. One previous study found a positive relationship between the amplitude of the P100 component of the VEP and V1 surface area, but not V1 thickness, in a small sample of healthy individuals. Here, we aimed to replicate these findings in a larger healthy control (HC) sample (n = 307) and to examine the same relationship in patients with SCZ_spect (n = 30) or BD (n = 45). We also compared the mean P100 amplitude, V1 surface area and V1 thickness between controls and patients and found no significant group differences. In HC only, we found a significant positive P100-V1 surface area association, while there were no significant P100-V1 thickness relationships in HC, SCZ_spect or BD. Together, our results confirm previous findings of a positive P100-V1 surface area association in HC, whereas larger patient samples are needed to further clarify the function-structure relationship in V1 in SCZ_spect and BD.

Hiccups, Hypersalivation, Hallucinations in Parkinson's Disease: New Insights, Mechanisms, Pathophysiology, and Management

Parkinson's disease (PD) is a chronic, progressive neurological disorder and the second most common neurodegenerative condition. We report three common but overlooked symptoms in PD-hiccups, hypersalivation, and hallucinations-in terms of their prevalence, pathophysiology, and up-to-date evidence-based treatment strategies. Whilst all these three symptoms do occur in many other neurological and non-neurological conditions, early recognition and treatment are paramount. Whilst hiccups affect 3% of healthy people, their rate of occurrence is higher (20%) in patients with PD. Hypersalivation (Sialorrhea) is another common neurological manifestation of many neurological and other neurodegenerative conditions such as motor neuron disease (MND), with a median prevalence rate of 56% (range: 32-74%). A 42% prevalence of sialorrhea is also reported in sub-optimally treated patients with PD. Hallucinations, especially visual hallucinations, are commonly reported, with a prevalence of 32-63% in PD, and a 55-78% prevalence is noted in patients with dementia with Lewy bodies (DLB), followed by tactile hallucinations, which are indicated by a sensation of crawling bugs or imaginary creatures across the skin surface. Whilst mainstay and primary management strategies for all these three symptoms are carried out through history taking, it is also essential to identify and treat possible potential triggers such as infection, minimise or avoid causative (such as drug-induced) factors, and especially carry out patient education before considering more definitive treatment strategies, such as botulinum toxin therapies for hypersalivation, to improve the quality of life of patients. This original review paper aims to provide a comprehensive overview of the disease mechanisms, pathophysiology, and management of hiccups, hypersalivation, and hallucinations in Parkinson's disease.

Auditory Hallucinations, Depressive Symptoms, and Current Suicidal Ideation or Behavior Among Patients with Acute-episode Schizophrenia

Suicide risk and auditory hallucinations are common in schizophrenia, but less is known about its associations. This cross-sectional study aimed to determine whether the presence and severity of auditory hallucinations were associated with current suicidal ideation or behavior (CSIB) among patients with schizophrenia. We interviewed 299 individuals with schizophrenia and acute symptoms and reviewed their medical records. Measurement included the Psychotic Symptom Rating Scale (PSYRATS-AH), the Calgary Depression Scale for Schizophrenia (CDSS), and the Positive and Negative Syndrome Scale. Logistic regression and path analysis were used. The CSIB prevalence was higher among patients with current auditory hallucination than those without (19.5% vs. 8.6%, crude odds ratio = 2.58, p = .009). Lifetime auditory hallucination experience (adjusted odds ratio [AOR] = 3.81; 95% CI: 1.45-10.05) or current auditory hallucination experience (AOR = 3.22; 95% CI: 1.25-8.28) can elevate the likelihood of CSIB while controlling for depressive symptoms and lifetime suicide-attempt history. Among those with auditory hallucinations, the emotional score of the PSYRATS-AH was positively associated with the CDSS score and there was a small indirect effect of the CDSS score on the association between the emotional domain score and CSIB (bias-corrected 95% CI, 0.02-0.20). In conclusion, the presence of auditory hallucinations was strongly associated with CSIB, independent of depressive symptoms and lifetime suicide attempts. Suicide risk assessment should consider auditory hallucination experience and patients' appraisal of its emotional characteristics. Future cohort studies are necessary to provide more conclusive evidence for the mediating pathways between auditory hallucinations and CSIB.HIGHLIGHTSThe presence of auditory hallucinations was associated with current suicidality.Auditory hallucinations' emotional severity was related to depressive symptoms.The severity of auditory hallucination was not directly associated with suicidality.

Dissociation, trauma and the experience of visual hallucinations in post-traumatic stress disorder and schizophrenia

Dissociative behaviours and hallucinations are often reported in trauma-exposed people with schizophrenia spectrum disorders and post-traumatic stress disorder (PTSD). Auditory hallucinations are the most commonly reported type of hallucination, but often co-occur with experiences in other sensory modalities. The phenomenology and the neurobiological systems involved in visual experiences are not well characterised. Are these experiences similar in nature, content or severity among people with schizophrenia and/or PTSD? What are the neurobiological bases of these visual experiences and what is the role of dissociative behaviours in the formation of these experiences? A study by Wearne and colleagues in BJPsych Open aimed to characterise these phenomenological systems in groups of people with PTSD, schizophrenia or both (schizophrenia + PTSD).

Prevalence and nature of multi-sensory and multi-modal hallucinations in people with first episode psychosis

Hallucinations can occur in single or multiple sensory modalities. This study explored how common these experiences were in people with first episode of psychosis (n = 82). Particular attention was paid to the number of modalities reported and whether the experiences were seen to be linked temporally and thematically. It was predicted that those people reporting a greater number of hallucinations would report more delusional ideation, greater levels of distress generally and lower functioning. All participants reported hallucinations in the auditory domain, given the nature of the recruitment. The participants also reported a range of other unusual sensory experiences, with visual and tactile hallucinations being reported by over half. Moreover, single sensory experiences or unimodal hallucinations were less common than two or more hallucination modalities which was reported by 78% of the participants. The number of hallucinations was significantly associated with greater delusional ideation and higher levels of general distress, but not with reduced functioning. It is clear there is a need to refine psychological treatments so that they are better matched to the actual experiences reported by people with psychosis. Theoretical implications are also considered.

Local Alterations of Left Arcuate Fasciculus and Transcallosal White Matter Microstructure in Schizophrenia Patients with Medication-resistant Auditory Verbal Hallucinations: A Pilot Study

Auditory verbal hallucinations (AVH) in schizophrenia (SZ) have been associated with abnormalities of the left arcuate fasciculus and transcallosal white matter projections linking homologous language areas of both hemispheres. While most studies have used a whole-tract approach, here we focused on analyzing local alterations of the above-mentioned pathways in SZ patients suffering medication-resistant AVH. Fractional anisotropy (FA) was estimated along the left arcuate fasciculus and interhemispheric projections of the rostral and caudal corpus callosum. Then, potential associations between white matter tracts and SZ symptoms were explored by correlating local site-by-site FA values and AVH severity estimated via the Auditory Hallucinations Rating Scale (AHRS). Compared to a sample of healthy controls, SZ patients displayed lower FA values in the rostral portion of the left arcuate fasciculus, near the frontal operculum, and in the left and right lateral regions of the rostral portion of the transcallosal pathways. In contrast, SZ patients showed higher FA values than healthy controls in the medial portion of the latter transcallosal pathway and in the midsagittal section of the interhemispheric auditory pathway. Finally, significant correlations were found between local FA values in the left arcuate fasciculus and the severity of the AVH's attentional salience. Contributing to the study of associations between local white matter alterations of language networks and SZ symptoms, our findings highlight local alterations of white matter integrity in these pathways linking language areas in SZ patients with AVH. We also hypothesize a link between the left arcuate fasciculus and the attentional capture of AVH.

Occurrence and phenomenology of hallucinations in the general population: A large online survey

Although epidemiological studies report that hallucinations occur in 6–15% of the general population, little is known about their phenomenology. To overcome this paucity, this study investigates the phenomenological characteristics of hallucinations in the general population, by using a nationally promoted online survey to assess hallucination phenomenology in four sensory modalities, through a self-report version of the Questionnaire for Psychotic Experiences (QPE), in 10,448 participants (aged 14–88 years). The phenomenology of hallucinations was assessed if hallucinations reportedly occurred in the past month. In the past month, auditory hallucinations were reported most frequently (29.5%), followed by visual (21.5%), tactile (19.9%), and olfactory hallucinations (17.3%); hallucinations in two or more modalities were reported by 47.6%. Substantial numbers of participants rated their hallucinations as severe, due to negative content (16.0–31.6%), previous bothersome experiences (14.8–20.2%), ensuing distress (10.5–16.8%), and/or ensuing disfunctioning (12.7–17.3%). Decreased insight was found in 10.2–11.4%. Hypnagogia was reported by 9.0–10.6%, and bereavement hallucinations by 2.8%. Despite a low prevalence of delusions (7.0%), these phenomena were significantly associated with recent hallucinations, observed in up to 13.4% of the participants with hallucinations during the past week (p < 0.001). Our results indicate a wide variety of the phenomenology of hallucinations in the general population and support the existence of a phenomenological continuum.

Language abnormalities in schizophrenia: binding core symptoms through contemporary empirical evidence

Both the ability to speak and to infer complex linguistic messages from sounds have been claimed as uniquely human phenomena. In schizophrenia, formal thought disorder (FTD) and auditory verbal hallucinations (AVHs) are manifestations respectively relating to concrete disruptions of those abilities. From an evolutionary perspective, Crow (1997) proposed that "schizophrenia is the price that Homo sapiens pays for the faculty of language". Epidemiological and experimental evidence points to an overlap between FTD and AVHs, yet a thorough investigation examining their shared neural mechanism in schizophrenia is lacking. In this review, we synthesize observations from three key domains. First, neuroanatomical evidence indicates substantial shared abnormalities in language-processing regions between FTD and AVHs, even in the early phases of schizophrenia. Second, neurochemical studies point to a glutamate-related dysfunction in these language-processing brain regions, contributing to verbal production deficits. Third, genetic findings further show how genes that overlap between schizophrenia and language disorders influence neurodevelopment and neurotransmission. We argue that these observations converge into the possibility that a glutamatergic dysfunction in language-processing brain regions might be a shared neural basis of both FTD and AVHs. Investigations of language pathology in schizophrenia could facilitate the development of diagnostic tools and treatments, so we call for multilevel confirmatory analyses focused on modulations of the language network as a therapeutic goal in schizophrenia.

Network analysis of psychiatric symptoms in schizophrenia: Findings from the Research on Asian Psychotropic Prescription Patterns for Antipsychotics (REAP-AP)

AIMS

Schizophrenia is a major mental disorder with a wide range of psychiatric symptoms. This study explored the structure of psychiatric symptoms of schizophrenia using network analysis in a large representative Asian sample based on a survey of clinical features and treatment used in schizophrenia patients across 15 countries/territories in Asia.

METHODS

Data on the demographic characteristics and psychiatric symptoms in schizophrenia patients were extracted from the dataset of the fourth Research on Asia Psychotropic Prescription for Antipsychotics (REAP-AP) project. The presence of the following psychiatric symptoms including delusions, hallucinations, disorganized speech, grossly disorganized or catatonic behavior, negative symptoms, social/occupational dysfunction, verbal aggression, physical aggression, and affective symptoms were analyzed.

RESULTS

A total of 3681 patients were included. The network analysis revealed that verbal aggression, hallucinations, and social/occupational dysfunction were the most central symptoms, while the connections between social/occupational dysfunction and verbal aggression, and between hallucinations and disorganized speech were the two strongest edges. There were significant gender differences in the network structure based on the network structure invariance test (M=0.74, P = 0.03) and invariant edge strength test. The positive correlation between verbal aggression and hallucinations was significantly stronger in the female network than that in the male network (P = 0.03), while a negative correlation between affective symptoms and negative symptoms was found in the female, but not the male network (P < 0.01).

CONCLUSION

Central symptoms including verbal aggression, hallucinations, and socio-occupational dysfunction should be addressed in developing targeted treatment strategy for schizophrenia patients.

Headache-Associated Phantosmia as a Harbinger of Lewy Body Dementia

Olfactory hallucinations, or phantosmias, can occur in many neurological, psychiatric, and medical conditions, but no widely used standardized approach exists to comprehensively assess qualitative olfactory dysfunction in the clinical setting. Additionally, medical professionals, patients, and their family members may not recognize phantosmia as a potentially neurological problem. Given the many possible etiologies for symptomatic phantosmia, it is important to recognize this unusual presentation and elicit a meaningful history to explore the potential underlying cause. We describe a 77-year-old gentleman with a two-year history of headaches accompanied by smelling a foul odor and discuss the differential diagnosis for new onset and persistent phantosmia. This unusual case ultimately manifested features consistent with Lewy body dementia, highlighting the varied clinical presentations that are possible with this neurodegenerative disorder. We discuss the possible pathophysiology of phantosmia in Lewy body disorders, including a proposed mechanism for olfactory hallucinations arising prior to the typical well-formed hallucinations in Lewy body dementia.

Distinguishing multimodal versus multisensory hallucinations in psychosis: Key definitions and a way forward

The study of hallucinations across multiple senses in psychosis has garnered renewed interest. Recent studies have adopted the term multimodal hallucinations to describe these experiences, yet some appear to be investigating a different, but related, phenomenon. In the current paper, we suggest use of the terms multimodal hallucinations and multisensory hallucinations to categorise distinct events that involve unusual sensory experiences across multiple domains. We propose that the constructs of temporality and relatedness are critical to delineating these experiences, where multimodal hallucinations refer to hallucinations in two or more sensory modes occurring concurrently in time and/or with significant thematic overlaps. Multisensory hallucinations conversely denote similar multisensory experiences, but with no temporal or relatedness constraints. This is accompanied by a decision-making framework for identifying whether a set of unusual perceptual experiences constitutes multimodal hallucinations or otherwise. We conclude by suggesting several priorities for future research, including empirical validation of our proposed model, further investigation of phenomenology, developing appropriate assessment tools and investigating underlying cognitive and other aetiological mechanisms.

From hallucinations to synaesthesia: A circular inference account of unimodal and multimodal erroneous percepts in clinical and drug-induced psychosis

Psychedelics distort perception and induce visual and multimodal hallucinations as well as synaesthesia. This is in contradiction with the high prevalence of distressing voices in schizophrenia. Here we introduce a unifying account of unimodal and multimodal erroneous percepts based on circular inference. We show that amplification of top-down predictions (descending loops) leads to an excessive reliance on priors and aberrant levels of integration of the sensory representations, resulting in crossmodal percepts and stronger illusions. By contrast, amplification of bottom-up information (ascending loops) results in overinterpretation of unreliable sensory inputs and high levels of segregation between sensory modalities, bringing about unimodal hallucinations and reduced vulnerability to illusions. We delineate a canonical microcircuit in which layer-specific inhibition controls the propagation of information across hierarchical levels: inhibitory interneurons in the deep layers exert control over priors, removing descending loops. Conversely, inhibition in the supragranular layers counterbalances the effects of the ascending loops. Overall, we put forward a multiscale and transnosographic account of erroneous percepts with important theoretical, conceptual and clinical implications.

Arts-based methods for hallucination research

INTRODUCTION

Neurocognitive models of hallucinations posit theories of misattribution and deficits in the monitoring of mental or perceptual phenomena but cannot yet account for the subjective experience of hallucinations across individuals and diagnostic categories. Arts-based research methods (ABRM) have potential for advancing research, as art depicts experiences which cognitive neuropsychiatry seeks to explain.

METHODS

To examine how incorporating ABRM may advance hallucination research and theories, we explore data on the lived experiences of hallucinations in psychiatric and neurological populations. We present a multiple case study of two empirical ABRM studies, which used participant-generated artwork and artist collaborations alongside interviews.

RESULTS

ABRM combined with interviews illustrated that hallucinations were infused with sensory features, characterised by embodiment, and situated within lived circumstances. These findings advance neurocognitive models of hallucinations by nuancing their multimodal nature, illustrating their embodied feelings, and exploring their content and themes. The process of generating artworks aided in disclosing difficult to discuss hallucinations, promoted participant self-reflection, and clarified multimodal details that may have been misconstrued through interview alone. ABRM were relevant and acceptable for participants and researchers.

CONCLUSION

ABRM may contribute to the development of neurocognitive models of hallucinations by making hallucination experiences more visible, tangible, and accessible.

Visual hallucinations in psychiatry - what aren't we seeing?

OBJECTIVE

To increase awareness of practising clinicians and researchers to the phenomenological distinctions between visual hallucinations and trauma-based, dissociative, visual re-experiencing phenomena seen in psychiatric disease.

CONCLUSIONS

The experience of visual hallucinations is not exclusive to psychotic disorders in psychiatry. Different forms of experiences that resemble visual hallucinations may occur in patients with a trauma background and may potentially affect diagnosis. Given the paucity of literature around the subject, it is imperative that further research aims to characterise the distinction between visual hallucinations in psychosis and visual phenomena associated with trauma.

Cognitive dysfunction and cortical structural abnormalities in first-episode drug-naïve schizophrenia patients with auditory verbal hallucination

OBJECTIVE

The current study aimed to examine the cognitive profiles and cortical structural alterations in first-episode drug-naïve schizophrenia with AVH (auditory verbal hallucination).

METHODS

Cortical structural parameters including cortical thickness and local gyrification index (LGI) estimated using FreeSurfer as well as cognitive performance assessed on the MATRICS Consensus Cognitive Battery (MCCB) were acquired from 78 schizophrenia patients with AVH, 74 schizophrenia patients without AVH (non-AVH), and 76 healthy controls (HC). Hoffman Auditory Hallucination Rating Scale (HAHRS) was applied to assess the severity of AVH.

RESULTS

The results revealed extensive deficits in all cognitive domains among AVH, non-AVH, and HC groups. Compared to non-AVH group, the AVH group showed poorer performance on visual learning and verbal learning domains. There were six brain regions with cortical thinning in the right hemisphere of inferior temporal gyrus, superior temporal gyrus, lateral orbito frontal cortex, rostral anterior cingulate cortex, supramarginal gyrus and insula, and two brain regions with increased LGI in the left hemisphere of superior parietal gyrus and the right hemisphere of caudal anterior cingulate cortex on AVH group relative to non-AVH group. Correlation analysis revealed that the cortical thickness in the right hemisphere of lateral orbito frontal cortex was negatively correlated with the severity of AVH in schizophrenia patients with AVH.

CONCLUSION

Visual learning, verbal learning dysfunction, and specific disruption of cortical structure may characterize schizophrenia patients with AVH during early stages of the disorder. Right lateral orbito frontal cortical deficits may be the pathological mechanisms underlying AVH in first-episode drug-naïve schizophrenia.

Objects that induce face pareidolia are prioritized by the visual system

The human visual system has evolved specialized neural mechanisms to rapidly detect faces. Its broad tuning for facial features is thought to underlie the illusory perception of faces in inanimate objects, a phenomenon called face pareidolia. Recent studies on face pareidolia suggest that the mechanisms underlying face processing, at least at the early stages of visual encoding, may treat objects that resemble faces as real faces; prioritizing their detection. In our study, we used breaking continuous flash suppression (b-CFS) to examine whether the human visual system prioritizes the detection of objects that induce face pareidolia over stimuli matched for object content. Similar to previous b-CFS results using real face stimuli, we found that participants detected the objects with pareidolia faces faster than object-matched control stimuli. Given that face pareidolia has been more frequently reported amongst individuals prone to hallucinations, we also explored whether this rapid prioritization is intact in individuals with schizophrenia, and found evidence suggesting that it was. Our findings suggest that face pareidolia engages a broadly tuned mechanism that facilitates rapid face detection. This may involve the proposed fast subcortical pathway that operates outside of visual awareness.

The Etiology of Auditory Hallucinations in Schizophrenia: From Multidimensional Levels

Enormous efforts have been made to unveil the etiology of auditory hallucinations (AHs), and multiple genetic and neural factors have already been shown to have their own roles. Previous studies have shown that AHs in schizophrenia vary from those in other disorders, suggesting that they have unique features and possibly distinguishable mechanisms worthy of further investigation. In this review, we intend to offer a comprehensive summary of current findings related to AHs in schizophrenia from aspects of genetics and transcriptome, neurophysiology (neurometabolic and electroencephalogram studies), and neuroimaging (structural and functional magnetic resonance imaging studies and transcriptome–neuroimaging association study). Main findings include gene polymorphisms, glutamate level change, electroencephalographic alterations, and abnormalities of white matter fasciculi, cortical structure, and cerebral activities, especially in multiple regions, including auditory and language networks. More solid and comparable research is needed to replicate and integrate ongoing findings from multidimensional levels.

Psychosis

PURPOSE OF REVIEW

Psychosis can manifest in primary psychotic disorders, neurologic diseases, and medical conditions. This article reviews the definition of psychotic symptoms and the evaluation and management of psychosis in primary psychiatric and neurologic disorders frequently seen in neurologic practice.

RECENT FINDINGS

Emerging evidence supports significant connections between psychosis and structural and functional brain changes in both primary psychotic and neurologic disorders. In addition to antidopaminergic activity, the mechanism of new-generation antipsychotics shifts to act on serotonin receptors, which potentially contributes to their benefits in the treatment of negative symptoms of psychosis and a lesser frequency of extrapyramidal side effects compared with typical antipsychotics. This is also helpful in the treatment of psychosis in patients who have neurodegenerative diseases and are vulnerable to developing extrapyramidal side effects from typical antipsychotics.

SUMMARY

Even with significant overlap, management of psychosis in primary psychotic disorders differs from the approach of psychosis in neurologic diseases. This article helps clinicians learn how to practically evaluate psychosis from both psychiatric and neurologic perspectives.

The feeling, embodiment and emotion of hallucinations in first episode psychosis: A prospective phenomenological visual-ecological study using novel multimodal unusual sensory experience (MUSE) maps

BACKGROUND

Research and practice typically focus upon unimodal hallucinations, especially auditory verbal hallucinations. Contemporary research has however indicated that voice-hearing may co-occur within a broader milieu of feelings, and multimodal hallucinations may be more common than previously thought.

METHODS

An observational design asked participants to prospectively document the feeling and modality of hallucinations for one week prior to an interview. Novel visual diary methods involving drawing, writing and body-mapping generated 42 MUSE maps (multimodal unusual sensory experience), analysed with a participatory qualitative method. Twelve people took part: all experiencing hallucinations daily, accessing early intervention in psychosis services, given psychotic-spectrum diagnoses, and living in the community. The study took place during a seven-month period in 2018 at Leicestershire and Rutland's Psychosis Intervention and Early Recovery service (UK).

FINDINGS

All documented hallucinations co-occurred with bodily feelings. Feelings were localised to specific body areas, generalised across the body and extended beyond the body into peripersonal space. Co-occurring emotional feelings most commonly related to confusion, fear and frustration.

INTERPRETATION

Hallucinations were characterised by numerous feelings arising at once, often including multimodal, emotional, and embodied features. Within this study, the immediate feeling of hallucination experiences were readily communicated through prospective, visual, and ecological information gathering methods and particularly those which offer multiple modes of communication (e.g. body-map, visual, written, oral). Uptake of visual, ecological and prospective methods may enhance understandings of lived experiences of hallucinations.Funding: University of Leicester.

Item-specific overlap between hallucinatory experiences and cognition in the general population: A three-step multivariate analysis of international multi-site data

Hallucinatory experiences (HEs) can be pronounced in psychosis, but similar experiences also occur in nonclinical populations. Cognitive mechanisms hypothesized to underpin HEs include dysfunctional source monitoring, heightened signal detection, and impaired attentional processes. Using data from an international multisite study on non-clinical participants (N = 419), we described the overlap between two sets of variables - one measuring cognition and the other HEs - at the level of individual items. We used a three-step method to extract and examine item-specific signal, which is typically obscured when summary scores are analyzed using traditional methodologies. The three-step method involved: (1) constraining variance in cognition variables to that which is predictable from HE variables, followed by dimension reduction, (2) determining reliable HE items using split-halves and permutation tests, and (3) selecting cognition items for interpretation using a leave-one-out procedure followed by repetition of Steps 1 and 2. The results showed that the overlap between HEs and cognition variables can be conceptualized as bi-dimensional, with two distinct mechanisms emerging as candidates for separate pathways to the development of HEs: HEs involving perceptual distortions on one hand (including voices), underpinned by a low threshold for signal detection in cognition, and HEs involving sensory overload on the other hand, underpinned by reduced laterality in cognition. We propose that these two dimensions of HEs involving distortions/liberal signal detection, and sensation overload/reduced laterality may map onto psychosis-spectrum and dissociation-spectrum anomalous experiences, respectively.

Tactile and Somatic Hallucinations in a Muslim Population of Psychotic Patients

Background: Tactile and somatic hallucinations are distressing phenomena that have hardly been researched. The few studies that have been published focus on their occurrence in neurodegenerative disorders and substance use, and, surprisingly, not on schizophrenia spectrum disorders. Objective: To fill this gap in our knowledge, we sought to explore the phenomenological characteristics of tactile and somatic hallucinations in a group of psychotic Muslim patients. Since many Muslims attribute such experiences to jinn (invisible spirits) and jinn are often perceived in multiple sensory modalities, we not only charted the involvement of the tactile and somatic modalities but also their interrelatedness with hallucinations in other sensory modalities. Methods: We performed a cross-sectional study using a semi-structured interview and dedicated questionnaire. Results: Of the 42 Muslim inpatients mostly diagnosed with a schizophrenia spectrum disorder, 62% reported to suffer from tactile and/or somatic hallucinations. Their phenomenological characteristics varied, with 96% being multimodal in nature and 38% taking the form of full-blown entity/jinn encounters. In comparison to other entity experiences, the involvement of the tactile and somatic modalities was exceptionally high, as was the level of ensuing distress. Regarding the order of recruitment of the various sensory modalities, we suggest the involvement of an underlying stochastic process. Conclusion: Muslim patients with severe psychosis can have tactile and somatic hallucinations, of which a large number are multimodal or full-blown entity/jinn encounters, which are almost invariably appreciated as harrowing. On the basis of our findings we make recommendations for further research and clinical practice.

Olfactory hallucinations in a population-based sample

Olfactory hallucinations referring to olfactory perceptions in the absence of chemical stimuli, occur in non-clinical and clinical populations. Few studies have investigated their prevalence in the general population and little is known about factors triggering and maintaining them such as substance use, severe life events, and mood. We analyzed self-report data from 2500 community dwelling Norwegians, aged 18-96 years, for occurrence of olfactory hallucinations and co-occurring hallucinations in other modalities (auditory, visual, tactile). Analyses included age, sex, self-reported symptoms of depression and anxiety, mental health status, and experience of severe life-events. The results show that 4.2% (95% CI 3.5-5.1%) reported having experienced olfactory hallucinations, and 56% of individuals experiencing olfactory hallucinations also reported these in combination with hallucinations in other modalities. Prevalence varied significantly in terms of age and sex, in that olfactory hallucinations were most frequently reported by young individuals and females. Self-reported symptoms of anxiety and experience of stressful life events were significantly associated with olfactory hallucinations, suggesting that experiencing olfactory hallucinations may negatively affect functioning and may increase the likelihood of developing psychopathology. Findings underline the need to continue to examine olfactory hallucinations albeit with a more comprehensive assessment in order to increase knowledge on this experience.

Evidence for an interrelated cluster of Hallucinatory experiences in the general population: an incidence study

BACKGROUND

Although hallucinations have been studied in terms of prevalence and its associations with psychopathology and functional impairment, very little is known about sensory modalities other than auditory (i.e. haptic, visual and olfactory), as well the incidence of hallucinations, factors predicting incidence and subsequent course.

METHODS

We examined the incidence, course and risk factors of hallucinatory experiences across different modalities in two unique prospective general population cohorts in the same country using similar methodology and with three interview waves, one over the period 1996-1999 (NEMESIS) and one over the period 2007-2015 (NEMESIS-2).

RESULTS

In NEMESIS-2, the yearly incidence of self-reported visual hallucinations was highest (0.33%), followed by haptic hallucinations (0.31%), auditory hallucinations (0.26%) and olfactory hallucinations (0.23%). Rates in NEMESIS-1 were similar (respectively: 0.35%, 0.26%, 0.23%, 0.22%). The incidence of clinician-confirmed hallucinations was approximately 60% of the self-reported rate. The persistence rate of incident hallucinations was around 20-30%, increasing to 40-50% for prevalent hallucinations. Incident hallucinations in one modality were very strongly associated with occurrence in another modality (median OR = 59) and all modalities were strongly associated with delusional ideation (median OR = 21). Modalities were approximately equally strongly associated with the presence of any mental disorder (median OR = 4), functioning, indicators of help-seeking and established environmental risk factors for psychotic disorder.

CONCLUSIONS

Hallucinations across different modalities are a clinically relevant feature of non-psychotic disorders and need to be studied in relation to each other and in relation to delusional ideation, as all appear to have a common underlying mechanism.

Schizotypal personality traits and multisensory integration: An investigation using the McGurk effect

Multisensory integration, the process by which sensory information from different sensory modalities are bound together, is hypothesized to contribute to perceptual symptomatology in schizophrenia, in whom multisensory integration differences have been consistently found. Evidence is emerging that these differences extend across the schizophrenia spectrum, including individuals in the general population with higher levels of schizotypal traits. In the current study, we used the McGurk task as a measure of multisensory integration. We measured schizotypal traits using the Schizotypal Personality Questionnaire (SPQ), hypothesizing that higher levels of schizotypal traits, specifically Unusual Perceptual Experiences and Odd Speech subscales, would be associated with decreased multisensory integration of speech. Surprisingly, Unusual Perceptual Experiences were not associated with multisensory integration. However, Odd Speech was associated with multisensory integration, and this association extended more broadly across the Disorganized factor of the SPQ, including Odd or Eccentric Behaviour. Individuals with higher levels of Odd or Eccentric Behaviour scores also demonstrated poorer lip-reading abilities, which partially explained performance in the McGurk task. This suggests that aberrant perceptual processes affecting individuals across the schizophrenia spectrum may relate to disorganized symptomatology.

Auditory Hallucinations: An Audiological Horizon?

BACKGROUND

 Interesting data and theories have emerged regarding auditory hallucinations (AHs) in patients with schizophrenia. The possibility that these patients may have changes in the anatomy of the auditory cortex and/or subcortical structures of the central auditory nervous system and present with deficits on audiological tests is important information to the audiology community. However, it seems clear that, in general, audiologists are not sufficiently aware of these findings.

PURPOSE

 There are two main purposes of this article: (1) to educate audiologists about AHs related to schizophrenia and related issues, and (2) to encourage audiologists and hearing scientists to become involved in the evaluation and research of AHs. This fascinating disorder is one in which audiologists/hearing scientists are well suited to make a significant contribution.

RESEARCH DESIGN

 A review and synthesis of the literature was conducted. Relevant literature was identified through PubMed, Google Scholar, as well as independent book chapters and article searches. Keywords driving the searches were AHs, auditory illusions, verbal and musical hallucinations, schizophrenia, and central auditory disorders. Given the currency of the topic, the information collected was primarily between 1990 and 2020.

STUDY SAMPLE

 The review is organized around categorization, prevalence, models, mechanisms, anatomy, pathophysiology, and audiological correlates related to AHs.

DATA COLLECTION AND ANALYSIS

 Searches were conducted using well-known search engines and manual searches by each author. This information on AHs was then analyzed collectively by the authors for useful background and relevance, as well as important for the field of audiology.

RESULTS

 Several anatomical, physiological, and functional imaging studies have shown compromise of the auditory cortex in those with schizophrenia and AHs. Potentially related to this, are studies that demonstrated sub-par performance on behavioral audiologic measures for this unique clinical population. These findings align well with the kind of hearing disorder for which audiologists are well-trained to make significant contributions.

CONCLUSION

 Neurobiological and audiological evidence is accumulating on patients with schizophrenia and AH potentially rendering it as both an auditory and psychiatric disorder. Audiologists should consider expanding their horizon and playing a role in the clinical investigation of this disorder.

Alterations of Resting EEG in Hallucinating and Nonhallucinating Schizophrenia Patients

Auditory hallucinations (AHs) are a common symptom of schizophrenia and contribute significantly to disease burden. Research on schizophrenia and AHs is limited and fails to adequately address the effect of AHs on resting EEG in patients with schizophrenia. This study assessed changes in frequency bands (delta, theta, alpha, beta) of resting EEG taken from hallucinating patients (n = 12), nonhallucinating patients (n = 11), and healthy controls (n = 12). Delta and theta activity were unaffected by AHs but differed between patients with schizophrenia and healthy controls. Alpha activity was affected by AHs: nonhallucinators had more alpha activity than hallucinators and healthy controls. Additionally, beta activity was inversely related to trait measures of AHs. These findings contribute to the literature of resting eyes closed EEG recordings of schizophrenia and AHs, and indicate the role of delta, theta, alpha, and beta as markers for schizophrenia and auditory hallucinations.

Leroy's elusive little people: A systematic review on lilliputian hallucinations

Lilliputian hallucinations concern hallucinated human, animal or fantasy entities of minute size. Having been famously described by the French psychiatrist Raoul Leroy in 1909, who wrote from personal experience, to date they are mentioned almost routinely in textbooks of psychiatry, albeit with little in-depth knowledge. I therefore systematically reviewed 145 case reports and case series comprising 226 case descriptions, concluding that lilliputian hallucinations are visual (61 %) or multimodal (39 %) in nature. In 97 % of the cases, they are perceived as grounded in the actual environment, thus indicating involvement of higher-level regions of the perceptual network subserving the fusion of sensory and hallucinatory content. Perceptual release and deafferentiation are the most likely underlying mechanisms. Etiology is extremely diverse, with schizophrenia spectrum disorder, alcohol use disorder and loss of vision accounting for 50 % of the cases and neurological disease for 36 %. Recovery was obtained in 62 % of the cases, whereas 18 % of the cases ended in chronicity and 8 % in death. Recommendations are made for clinical practice and future research.

Multimodal versus unimodal auditory hallucinations in clinical practice: Clinical characteristics and treatment outcomes

Psychological treatments for hallucinations typically target auditory verbal hallucinations (AVH) but neglect the influence of hallucinations in other sensory modalities. This study compared the baseline clinical characteristics and therapeutic outcomes (following brief Coping Strategy Enhancement) of adult clients (N = 100) with multimodal or unimodal (auditory) hallucinations attending an outpatient service for distressing AVH. The results showed that 72.1% of clients reported multimodal hallucinations in the past month. Group comparisons of most baseline clinical characteristics (AVH features, beliefs about AVH, number of traumatic events, personal and social functioning, negative affect) were non-significant. However, in the subgroup (N = 65) reporting ongoing effects of traumatic events, those with multimodal hallucinations reported significantly higher posttraumatic stress symptoms (d = 0.62). Notably, both multimodal and unimodal hallucination groups showed improvement in AVH distress and frequency post-treatment, but group differences in treatment outcomes were not significant. These findings, in a naturalistic service setting, confirm that multimodal hallucinations are common in people seeking help for distressing AVH and may be associated with higher levels of posttraumatic stress symptoms. Importantly, they also suggest that psychological therapy may be suitable and effective for clients experiencing AVH - irrespective of the presence of hallucinations in other sensory modalities.

The Relationship Between Multisensory Temporal Processing and Schizotypal Traits

Recent literature has suggested that deficits in sensory processing are associated with schizophrenia (SCZ), and more specifically hallucination severity. The DSM-5's shift towards a dimensional approach to diagnostic criteria has led to SCZ and schizotypal personality disorder (SPD) being classified as schizophrenia spectrum disorders. With SCZ and SPD overlapping in aetiology and symptomatology, such as sensory abnormalities, it is important to investigate whether these deficits commonly reported in SCZ extend to non-clinical expressions of SPD. In this study, we investigated whether levels of SPD traits were related to audiovisual multisensory temporal processing in a non-clinical sample, revealing two novel findings. First, less precise multisensory temporal processing was related to higher overall levels of SPD symptomatology. Second, this relationship was specific to the cognitive-perceptual domain of SPD symptomatology, and more specifically, the Unusual Perceptual Experiences and Odd Beliefs or Magical Thinking symptomatology. The current study provides an initial look at the relationship between multisensory temporal processing and schizotypal traits. Additionally, it builds on the previous literature by suggesting that less precise multisensory temporal processing is not exclusive to SCZ but may also be related to non-clinical expressions of schizotypal traits in the general population.

The Phenomenology and Neurobiology of Visual Distortions and Hallucinations in Schizophrenia: An Update

Schizophrenia is characterized by visual distortions in ~60% of cases, and visual hallucinations (VH) in ~25-50% of cases, depending on the sample. These symptoms have received relatively little attention in the literature, perhaps due to the higher rate of auditory vs. visual hallucinations in psychotic disorders, which is the reverse of what is found in other neuropsychiatric conditions. Given the clinical significance of these perceptual disturbances, our aim is to help address this gap by updating and expanding upon prior reviews. Specifically, we: (1) present findings on the nature and frequency of VH and distortions in schizophrenia; (2) review proposed syndromes of VH in neuro-ophthalmology and neuropsychiatry, and discuss the extent to which these characterize VH in schizophrenia; (3) review potential cortical mechanisms of VH in schizophrenia; (4) review retinal changes that could contribute to VH in schizophrenia; (5) discuss relationships between findings from laboratory measures of visual processing and VH in schizophrenia; and (6) integrate findings across biological and psychological levels to propose an updated model of VH mechanisms, including how their content is determined, and how they may reflect vulnerabilities in the maintenance of a sense of self. In particular, we emphasize the potential role of alterations at multiple points in the visual pathway, including the retina, the roles of multiple neurotransmitters, and the role of a combination of disinhibited default mode network activity and enhanced state-related apical/contextual drive in determining the onset and content of VH. In short, our goal is to cast a fresh light on the under-studied symptoms of VH and visual distortions in schizophrenia for the purposes of informing future work on mechanisms and the development of targeted therapeutic interventions.

Time Distortions: A Systematic Review of Cases Characteristic of Alice in Wonderland Syndrome

Of the perceptual distortions characteristic of Alice in Wonderland syndrome, substantial alterations in the immediate experience of time are probably the least known and the most fascinating. We reviewed original case reports to examine the phenomenology and associated pathology of these time distortions in this syndrome. A systematic search in PubMed, Ovid Medline, and the historical literature yielded 59 publications that described 168 people experiencing time distortions, including 84 detailed individual case reports. We distinguished five different types of time distortion. The most common category comprises slow-motion and quick-motion phenomena. In 39% of all cases, time distortions were unimodal in nature, while in 61% there was additional involvement of the visual (49%), kinaesthetic (18%), and auditory modalities (14%). In all, 40% of all time distortions described were bimodal in nature and 19% trimodal, with 1% involving four modalities. Underlying neurological mechanisms are varied and may be triggered by intoxications, infectious diseases, metabolic disorders, CNS lesions, paroxysmal neurological disorders, and psychiatric disorders. Bizarre sensations of time alteration-such as time going backwards or moving in circles-were mostly associated with psychosis. Pathophysiologically, mainly occipital areas appear to be involved, although the temporal network is widely disseminated, with separate component timing mechanisms not always functioning synchronously, thus occasionally creating temporal mismatches within and across sensory modalities (desynchronization). Based on our findings, we propose a classification of time distortions and formulate implications for research and clinical practice.

Hallucinations Under Psychedelics and in the Schizophrenia Spectrum: An Interdisciplinary and Multiscale Comparison

The recent renaissance of psychedelic science has reignited interest in the similarity of drug-induced experiences to those more commonly observed in psychiatric contexts such as the schizophrenia-spectrum. This report from a multidisciplinary working group of the International Consortium on Hallucinations Research (ICHR) addresses this issue, putting special emphasis on hallucinatory experiences. We review evidence collected at different scales of understanding, from pharmacology to brain-imaging, phenomenology and anthropology, highlighting similarities and differences between hallucinations under psychedelics and in the schizophrenia-spectrum disorders. Finally, we attempt to integrate these findings using computational approaches and conclude with recommendations for future research.

Schizotypal traits are not related to multisensory integration or audiovisual speech perception

Multisensory integration, the binding of sensory information from different sensory modalities, may contribute to perceptual symptomatology in schizophrenia, including hallucinations and aberrant speech perception. Differences in multisensory integration and temporal processing, an important component of multisensory integration, are consistently found in schizophrenia. Evidence is emerging that these differences extend across the schizophrenia spectrum, including individuals in the general population with higher schizotypal traits. In the current study, we investigated the relationship between schizotypal traits and perceptual functioning, using audiovisual speech-in-noise, McGurk, and ternary synchrony judgment tasks. We measured schizotypal traits using the Schizotypal Personality Questionnaire (SPQ), hypothesizing that higher scores on Unusual Perceptual Experiences and Odd Speech subscales would be associated with decreased multisensory integration, increased susceptibility to distracting auditory speech, and less precise temporal processing. Surprisingly, these measures were not associated with the predicted subscales, suggesting that these perceptual differences may not be present across the schizophrenia spectrum.

Distinct hierarchical alterations of intrinsic neural timescales account for different manifestations of psychosis

Hierarchical perceptual-inference models of psychosis may provide a holistic framework for understanding psychosis in schizophrenia including heterogeneity in clinical presentations. Particularly, hypothesized alterations at distinct levels of the perceptual-inference hierarchy may explain why hallucinations and delusions tend to cluster together yet sometimes manifest in isolation. To test this, we used a recently developed resting-state fMRI measure of intrinsic neural timescale (INT), which reflects the time window of neural integration and captures hierarchical brain gradients. In analyses examining extended sensory hierarchies that we first validated, we found distinct hierarchical INT alterations for hallucinations versus delusions in the auditory and somatosensory systems, thus providing support for hierarchical perceptual-inference models of psychosis. Simulations using a large-scale biophysical model suggested local elevations of excitation-inhibition ratio at different hierarchical levels as a potential mechanism. More generally, our work highlights the robustness and utility of INT for studying hierarchical processes relevant to basic and clinical neuroscience.