Abstract Background and Hypothesis Visual hallucinations (VH) are a core symptom of both Lewy body diseases (LBDs; eg, Parkinson’s disease and dementia with Lewy bodies) and serotonergic psychedelics (SPs; eg, psilocybin and mescaline). While these conditions differ in etiology, overlapping phenomenology, and neural mechanisms suggest shared pathways. This review explores similarities and...
The diagnostic category of sleep-related hallucinations (SRH) replaces the previous category of Terrifying Hypnagogic Hallucinations in the 2001 edition of International Classification of Sleep Disorders-R. Hypnagogic and hypnopompic hallucinations (HHH) that occur in the absence of other symptoms or disorder and, within the limits of normal sleep, are most likely non-pathological. By contrast,...
Hallucinations are one of the most interesting and least understood of all human experiences. This commentary addresses the ideas which most influenced my thinking in the past 20 years and what I believe to be the most currently promising area of enquiry. Interest in hallucinations reaches far back into antiquity and across cultures. The similarity of hallucinations in mental illness with the...
Visual experiences such as hallucinations are commonly reported by people with psychosis, psychological trauma and dissociative states, although questions remain about their similarities and differences. For diagnostic and therapeutic purposes, clinical research must better delineate and compare the characteristics of these experiences in post-traumatic stress disorder (PTSD) and in...
Within the broad field of human perception lies the category of stimulus-independent perceptions, which draws together experiences such as hallucinations, mental imagery and dreams. Traditional divisions between medical and psychological sciences have contributed to these experiences being investigated separately. This review aims to examine their similarities and differences at the levels of...
Abstract 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...
That trauma can play a significant role in the onset and maintenance of voice-hearing is one of the most striking and important developments in the recent study of psychosis. Yet the finding that trauma increases the risk for hallucination and for psychosis is quite different from the claim that trauma is necessary for either to occur. Trauma is often but not always associated with...
Background: Going without sleep for long periods of time can produce a range of experiences, including perceptual distortions and hallucinations. Many questions, however, remain unanswered regarding the types of symptoms which are most reliably elicited, the time of symptom onset, and whether symptoms worsen over time towards psychotic decompensation. Since sleep deprivation exceeding 48 h is...
Little is known about the presence of parasomnias such as nightmare disorder, sleep paralysis, REM sleep behavior disorder (RBD), and sleep-related eating disorders (SRED) in people with mental illness. A predominant view suggests that psychotropic medications might be contributing to parasomnias. This article summarizes knowledge regarding the relationships between psychiatric disorders and...
Hallucinations constitute one of the 5 symptom domains of psychotic disorders in DSM-5, suggesting diagnostic significance for that group of disorders. Although specific featural properties of hallucinations (negative voices, talking in the third person, and location in external space) are no longer highlighted in DSM, there is likely a residual assumption that hallucinations in schizophrenia...
This special theme in Schizophrenia Bulletin on Hallucinations includes three interdisciplinary articles presented at the International Consortium on Hallucination Research (ICHR) meeting in Melbourne, Australia, October 2015. 1 A common theme recapitulated through each of the reports relates to refining and/or improving our conceptualization and understanding of brain mechanisms and dynamics,...
By definition, hallucinations occur only in the full waking state. Yet similarities to sleep-related experiences such as hypnagogic and hypnopompic hallucinations, dreams and parasomnias, have been noted since antiquity. These observations have prompted researchers to suggest a common aetiology for these phenomena based on the neurobiology of rapid eye movement (REM) sleep. With our recent...
In recent years, there has been increasing interest in the potential for alterations to the brain's resting-state networks (RSNs) to explain various kinds of psychopathology. RSNs provide an intriguing new explanatory framework for hallucinations, which can occur in different modalities and population groups, but which remain poorly understood. This collaboration from the International...
We explore how hallucinations might be studied within the National Institute of Mental Health (NIMH) Research Domain Criteria (RDoC) framework, which asks investigators to step back from diagnoses based on symptoms and focus on basic dimensions of functioning. We start with a description of the objectives of the RDoC project and its domains and constructs. Because the RDoC initiative asks...
This Special Supplement presents reports from 11 working groups of the interdisciplinary International Consortium on Hallucination Research meeting in Durham, UK, September 2013. Topics include psychological therapies for auditory hallucinations, culture and hallucinations, hallucinations in children and adolescents, visual hallucinations, interdisciplinary approaches to the phenomenology of...
Much of the research on visual hallucinations (VHs) has been conducted in the context of eye disease and neurodegenerative conditions, but little is known about these phenomena in psychiatric and nonclinical populations. The purpose of this article is to bring together current knowledge regarding VHs in the psychosis phenotype and contrast this data with the literature drawn from...
This article presents a report on the 2nd meeting of the International Consortium on Hallucination Research, held on September 12th and 13th 2013 at Durham University, UK. Twelve working groups involving specialists in each area presented their findings and sought to summarize the available knowledge, inconsistencies in the field, and ways to progress. The 12 working groups reported on the...