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

Blom, Jan Dirk

doi:10.1016/j.neubiorev.2021.03.002

Cited by 8 publications

(6 citation statements)

References 26 publications

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“…An important task for future research, therefore, involves clarifying the factors that determine the differential expression of the proposed mechanisms across patients. Specific questions include whether the VH of patients with retinal impairments differ from those with normal retinal function (and if so, in what ways), and exploration of the differences (e.g., in trauma history) between patients with threatening or survival-related VH imagery and patients with VH without such content [geometric hallucinations or VH involving lilliputian figures (180)].…”

Section: An Updated Model Of Vh and Visual Distortions In Schizophreniamentioning

confidence: 99%

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

Silverstein

Lai

2021

Front. Psychiatry

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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.

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Section: An Updated Model Of Vh and Visual Distortions In Schizophreniamentioning

confidence: 99%

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

Silverstein

Lai

2021

Front. Psychiatry

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“…Another so-called near-death experiencer (NDEr), Stephen, and his and his lilliputian hallucinations when he overdosed with opioids, is equally fascinating. Sometime after taking the pills, he was surprised to suddenly awaken to an ensemble of 'midgets' milling around hima meme of some psychedelics, especially dimethyltryptamine (DMT; the short-acting serotonergic tryptamine) experiences and neuropsychiatric hallucinations (Blom, 2021)-but certainly not NDEs. Most tellingly, Stephen reported eventually leaving his body and viewing himself from a distance-though from this vantage point no longer seeing the dwarfy denizens; as he said, "my body was confused .…”

Section: Commentarymentioning

confidence: 99%

Commentary on After: A Doctor Explores What Near-Death Experiences Reveal About Life and Beyond, by Bruce Greyson, MD

Michael¹

2021

JNDS

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Near-death experiences (NDEs) are a typically profound set of experiences occasioned during both actual and subjective proximity to death. In March of 2021, Bruce Greyson, MD, one of the original researchers founding the field of near-death studies, published the book, After. It represents a thought-provoking and highly readable chronicling of an almost half-century of both his impressive scholarship and personal experience of changing worldview. In the present article, I provide a thorough essay-style analysis of the publication, focusing on how much of what Greyson reported is consistent with, yet also lacks considerable recognition of, the model of NDEs provided by a psychedelic framework. That is, substantial explanatory power can be derived from considering NDEs as a psychedelic phenomenon in terms of possible neurobiological correlates, its acute state, long-term sequalae, and putatively parapsychological effects. In writing this article, I hold no a priori ontological assumptions but hope at least to offer the necessary neurally-oriented explanations where the literature indicates them. However, I also note that certain NDE dimensions may not yet be fully explicated in terms of such a reductionist paradigm, and even where they could be, the 'hard problem of consciousness' is still to be resolved within the natural sciences. Although I believe the book would have benefited from this embrace of the phenomenon's likely mediation by such endogenous neurotransmission, or convergence on similar mechanisms, I nevertheless affirm that Greyson has delivered a laudable exposition of the transcendent experience as having deep psychiatric, personal, interpersonal, ethical, and possibly metaphysical implications.

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“…The incubus phenomenon can thus be characterized as an entity experience superimposed on a state of sleep paralysis. Like other entity experiences, such as lilliputian hallucinations ( 26 ), dimethyltryptamine-induced machine elves ( 27 ), God experiences ( 28 ), and hallucinations attributed to jinn ( 29 ), there appears to be a fixed order to the sensory modalities that are being recruited, at least during the initial stages of the process, which invariably starts out with the somatosensory modality (muscle atonia), followed by the tactile modality (the sense of pressure being exerted on the chest), and then the visual modality (seeing a person or entity sitting on top of one’s body). During the stages that follow, modalities such as the sexual, auditory, olfactory, and vestibular modalities may or may not be recruited.…”

Section: Discussionmentioning

confidence: 99%

The incubus phenomenon: Prevalence, frequency and risk factors in psychiatric inpatients and university undergraduates

et al. 2022

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BackgroundThe incubus phenomenon is a paroxysmal sleep-related disorder characterized by the visuotactile sensation of a person or entity exerting pressure on one’s thorax during episodes of sleep paralysis and (apparent) wakefulness. This terrifying phenomenon is relatively unknown even though a previous meta-analysis indicated a lifetime prevalence of 0.11 for individuals in the general population and of 0.41 for selected at-risk groups, including people diagnosed with schizophrenia and students. Since the studies reviewed did not always make a strict distinction between the incubus phenomenon and isolated sleep paralysis, we carried out a cross-sectional study in a contemporary patient and student sample to attain current, more detailed data on the incubus phenomenon.Materials and methodsIn a cross-sectional design, we used the Waterloo Unusual Sleep Experience Questionnaire (WUSEQ) to screen patients with severe psychiatric disorders and university undergraduates to establish and compare prevalence rates, frequencies of occurrence, and risk factors for the incubus phenomenon.ResultsHaving interviewed 749 people, comprising 606 students and 143 patients with a schizophrenia spectrum or related disorder who had been acutely admitted to a secluded nursing ward, we computed a reported lifetime prevalence of 0.12 and 0.09, respectively, which rates were not statistically different. In both groups, the phenomenon was more common in people with a non-Western European background. Risk factors noted for the students were the use of psychotropic medication and the lifetime presence of an anxiety disorder, eating disorder, or sleeping disorder. We found no associations with age or gender in either group.ConclusionThe 0.09 and 0.12 lifetime prevalence rates we recorded for the incubus phenomenon in students and psychiatric inpatients is substantially lower than the 0.41 found in an earlier meta-analysis. We tentatively attribute this difference to an overgeneralization in previous studies but also discuss alternative explanations. The elevated prevalence among non-Western European participants may well be due to the fact that the topic continues to be part of the cultural and religious heritage of many non-Western countries.

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

Cited by 8 publications

References 26 publications

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

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

Commentary on After: A Doctor Explores What Near-Death Experiences Reveal About Life and Beyond, by Bruce Greyson, MD

The incubus phenomenon: Prevalence, frequency and risk factors in psychiatric inpatients and university undergraduates

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