Measures of visual hallucinations: Review and recommendations

Measures of mental imagery in emotional disorders: A COSMIN systematic review of psychometric properties

BACKGROUND

Dysfunctional imagery processes characterise a range of emotional disorders. Valid, reliable, and responsive mental imagery measures may support the clinical assessment of imagery and advance research to develop theory and imagery-based interventions. We sought to review the psychometric properties of mental imagery measures relevant to emotional disorders.

METHODS

A systematic review registered on the Open Science Framework was conducted using COnsensus-based Standards for the selection of health Measurement INstruments (COSMIN) guidance. Five databases were searched. COSMIN tools were used to assess the quality of study methodologies and psychometric properties of measures.

RESULTS

Twenty-three articles describing twenty-one self-report measures were included. Measures assessed various imagery processes and were organised into four groups based on related emotional disorders. Study methodological quality varied: measure development and reliability studies were generally poor, while internal consistency and hypothesis testing studies were higher quality. Most measurement properties assessed were of indeterminate quality.

CONCLUSION

Imagery measures were heterogenous and primarily disorder specific. Due to a lack of high-quality psychometric assessment, it is unclear whether most included imagery measures are valid, reliable, or responsive. Measures had limited evidence of content validity suggesting further research could engage clinical populations to ensure their relevance and comprehensiveness.

Understanding visual hallucinations: a new synthesis

Despite decades of research, we do not definitively know how people sometimes see things that are not there. Eight models of complex visual hallucinations have been published since 2000, including Deafferentation, Reality Monitoring, Perception and Attention Deficit, Activation, Input, and Modulation, Hodological, Attentional Networks, Active inference, and Thalamocortical Dysrhythmia Default Mode Network Decoupling. Each was derived from different understandings of brain organisation. To reduce this variability, representatives from each research group agreed an integrated Visual Hallucination Framework that is consistent with current theories of veridical and hallucinatory vision. The Framework delineates cognitive systems relevant to hallucinations. It allows a systematic, consistent, investigation of relationships between the phenomenology of visual hallucinations and changes in underpinning cognitive structures. The episodic nature of hallucinations highlights separate factors associated with the onset, persistence, and end of specific hallucinations suggesting a complex relationship between state and trait markers of hallucination risk. In addition to a harmonised interpretation of existing evidence, the Framework highlights new avenues of research, and potentially, new approaches to treating distressing hallucinations.

Prevalence of multisensory hallucinations in people at risk of transition to psychosis

Hallucinations can occur in single or multiple sensory modalities. Greater attention has been paid to single sensory experiences with a comparative neglect of hallucinations that occur across two or more sensory modalities (multisensory hallucinations). This study explored how common these experiences were in people at risk of transition to psychosis (n=105) and considered whether a greater number of hallucinatory experiences increased delusional ideation and reduced functioning, both of which are associated with a greater risk of transition to psychosis. Participants reported a range of unusual sensory experiences, with two or three being common. However, when a strict definition of hallucinations was applied, in which the experience has the quality of a real perception and in which the person believes them to be real experiences, then multisensory experiences were rare and when reported, single sensory hallucinations in the auditory domain were most common. The number of unusual sensory experiences or hallucinations was not significantly associated with greater delusional ideation or poorer functioning. Theoretical and clinical implications are discussed.

What is the frequency and nature of visual hallucinations in non-clinical participants?

OBJECTIVES

There is a paucity of psychological treatments for visual hallucinations (VH). A key aspect in the psychological treatment of hallucination-related distress is normalisation to explain that these experiences are commonplace and can be non-distressing. In order to normalise VH, it is vital that more is known about VH in non-clinical populations. This study investigated the prevalence, content, context, appraisals, distress, and behavioural reactions to VH in a non-clinical sample.

DESIGN

A cross-sectional study was conducted.

METHODS

466 students completed the Multi-Modality Unusual Sensory Experiences Questionnaire-VH subscale with additional contextual follow-up questions.

RESULTS

Of the 466 participants, 395 (84.8%) reported anomalous visual experiences. 176 (37.77%) participants reported VH similar to the content seen in psychosis. Of the overall sample, 17.38% felt their experience met the VH definition. Participants mainly saw figures, when alone and in the evening. Participants endorsed normalising appraisals: 112 out of 176 (78.87%) believed their mind was playing tricks on them and 83 (58.45%) believed they were tired. However, many also believed the VH was a threat to their mental (66, 46.48%) or physical well-being (41, 28.87%). These negative appraisals were associated with distress.

CONCLUSION

VH are seemingly common in non-clinical populations and are similar in a number of ways to those of people with psychosis. Awareness that VH occur on a continuum could normalise people's experiences and reduce their negative appraisals and related distress.

Visual phenomenology in schizophrenia and post-traumatic stress disorder: an exploratory study

BACKGROUND

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 schizophrenia.

AIMS

To compare visual phenomena and dissociation in participants with a primary psychotic illness and those with a trauma diagnosis.

METHOD

A quantitative group design study comparing visual phenomena in three participant groups who also have a history of hearing voices: schizophrenia and no trauma history (n = 19), PTSD with dissociation (n = 17) and comorbid schizophrenia and PTSD (n = 20). Validated clinical measures included the North-East Visual Hallucination Interview, PTSD Symptoms Scale Interview, Clinician Administered Dissociative States Scale, Psychotic Symptoms Rating Scales and Positive and Negative Syndrome Scale.

RESULTS

There was a remarkable similarity in visual experiences, including rates of complex visual hallucinations, between the three diagnostic groups. There were no significant differences in the severity or components of distress surrounding the visual experiences. Dissociation predicted visual hallucination severity for the comorbid schizophrenia and PTSD group, but not for PTSD or schizophrenia alone.

CONCLUSIONS

Visual experiences in PTSD can include visual hallucinations that are indistinguishable from those experienced in schizophrenia. Multimodal hallucinations are frequently observed in both schizophrenia and PTSD. A model for visual hallucinations in PTSD is suggested, following two separate neurobiological pathways based on distinct responses to trauma.

A Multimodal Neuroimaging and Neuropsychological Study of Visual Hallucinations in Alzheimer’s Disease

Background: Hallucinations in Alzheimer’s disease (AD) have been linked to more severe cognitive and functional decline. However, research on visual hallucinations (VH), the most common type of hallucinations in AD, is limited. Objective: To investigate the cognitive and cerebral macrostructural and metabolic features associated with VH in AD. Methods: Twenty-four AD patients with VH, 24 with no VH (NVH), and 24 cognitively normal (CN) matched controls were selected from the Alzheimer’s Disease Neuroimaging Initiative (ADNI) database. Differences in regional gray matter (GM) volumes and cognitive performance were investigated with whole brain voxel-based morphometry analyses of MRI structural brain scans, and analyses of neuropsychological tests. Glucose metabolic changes were explored in a subsample of patients who had FDG-PET scans available. Results: More severe visuoconstructive and attentional deficits were found in AD VH compared with NVH. GM atrophy and hypometabolism were detected in occipital and temporal areas in VH patients in comparison with CN. On the other hand, NVH patients had atrophy and hypometabolism mainly in temporal areas. No differences in GM volume and glucose metabolism were found in the direct comparison between AD VH and NVH. Conclusion: In addition to the pattern of brain abnormalities typical of AD, occipital alterations were observed in patients with VH compared with CN. More severe visuoconstructive and attentional deficits were found in AD VH when directly compared with NVH, and might contribute to the emergence of VH in AD.

Visual hallucinations in 246-km mountain ultra-marathoners: An observational study

Ultra-marathons are typically held over harsh terrains such as mountains, deserts, or other wilderness, and place severe demands on the physical and psychological capabilities of participants. Adventure-race competitors commonly report hallucinations. The goal of this study was to gain insight into visual hallucinations (VHs) during a mountain ultra-marathon. Thirty-one Taiwanese runners who participated in the 2018 Run Across Taiwan Ultra-Marathon, which spans 246 km with an altitude difference of 3266 m and an overall cut-off time of 44 h, volunteered for this study. Self-reported questionnaires on sleep duration, hallucinatory experiences, clinical symptoms of cold- and heat-related illnesses, and the 2018 Lake Louise Acute Mountain Sickness (AMS) Score were recorded prerace, during the summit, immediately postrace, and 3-days postrace. Hematological samples were collected 1 week before, immediately after, and 3 days after the race. Eight ultra-marathoners (six males and two females; seven finishers and one withdrawer) were recruited. Three out of eight (37.5%) subjects (two males and one female) reported experiencing VHs during the last 60 km. Three out of five (60%) lower-ranked subjects experienced VHs. All eight runners slept for <30 min during the race. None of the runners presented with headache either during or after the race to meet the criteria for AMS. None of the runners suffered an abnormal thermoregulatory response or a hypoglycemic episode throughout the ultra-marathon. The changes in blood osmolality immediately postrace were subclinical, despite being statistically significant. Among the three runners with VHs, none presented with severe dehydration or dysnatremia immediately postrace. High-altitude exposure, hyper/hypothermia, dehydration, dysnatermia, or hypoglycemia did not seem to contribute to hallucination onset in our subjects during the event. VHs of ultra-marathoners may be associated with excessive physical exertion and sleep deprivation.

Knowledge domain and emerging trends in visual hallucination research: A scientometric analysis

BACKGROUND

Visual hallucination (VH) refers to a spontaneous visual perception without corresponding external stimuli and often occurs in ophthalmological and neuropsychiatric disorders. It is associated with poor quality of life, and increased patient hospitalization and nursing home admission. To date, a scientometric analysis of research on VH is lacking.

AIM

To objectively summarize the features of VH research and gain insights into the emerging trends in research on VH.

METHODS

CiteSpace V was used in this article. Publication outputs, document types, geographic distributions, co-authorship status, research hotspots, and co-citation status were analyzed. A total of 2176 original articles and 465 reviews were included in the database downloaded from the Web of Science Core Collection. We selected the top 50 most cited or occurring articles or items to create a visualized network with a 1-year interval. In the document co-citation analysis stage, we performed clustering analysis on co-cited references, and log likelihood tests were used to name the clusters.

RESULTS

The results showed that most publications can be classified into neurology, sports, and ophthalmology studies. In addition, North America, Europe, Asia and Australia published the most documents. Some well-known authors have always had a leading role in this field; meanwhile, new authors keep emerging. A relatively stable cooperation has been formed among many authors. Furthermore, neuropsychiatric symptom and functional connectivity are the top hotspots. Research on VH in dementia with Lewy bodies and Parkinson’s disease (PD) have received much attention. Studies on VH in PD are likely to be the new emerging trends in the future, especially the mechanisms of VH.

CONCLUSION

Research on VH has formed a complete system. More large-scale clinical and in-depth basic research are required to better understand the mechanisms underlying VH, which will contribute to our understanding of the pathophysiology and therapeutic options for VH.

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

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

The Strasbourg Visual Scale: A Novel Method to Assess Visual Hallucinations

The experience of oneself in the world is based on sensory afferences, enabling us to reach a first-perspective perception of our environment and to differentiate oneself from the world. Visual hallucinations may arise from a difficulty in differentiating one's own mental imagery from externally-induced perceptions. To specify the relationship between hallucinations and the disorders of the self, we need to understand the mechanisms of hallucinations. However, visual hallucinations are often under reported in individuals with psychosis, who sometimes appear to experience difficulties describing them. We developed the "Strasbourg Visual Scale (SVS)," a novel computerized tool that allows us to explore and capture the subjective experience of visual hallucinations by circumventing the difficulties associated with verbal descriptions. This scale reconstructs the hallucinated image of the participants by presenting distinct physical properties of visual information, step-by-step to help them communicate their internal experience. The strategy that underlies the SVS is to present a sequence of images to the participants whose choice at each step provides a feedback toward re-creating the internal image held by them. The SVS displays simple images on a computer screen that provide choices for the participants. Each step focuses on one physical property of an image, and the successive choices made by the participants help them to progressively build an image close to his/her hallucination, similar to the tools commonly used to generate facial composites. The SVS was constructed based on our knowledge of the visual pathways leading to an integrated perception of our environment. We discuss the rationale for the successive steps of the scale, and to which extent it could complement existing scales.

Evaluating a novel behavioral paradigm for visual hallucinations in Dementia with Lewy bodies

The aim of this study was to evaluate the utility of the Bistable Percept Paradigm (BPP), a computerised behavioural task that has previously been utilised for the assessment of visual hallucinations in Parkinson's Disease, in a Dementia with Lewy bodies (DLB) cohort. Dementia with Lewy bodies patients demonstrated poorer performance than healthy controls (HC) on the BPP with significantly more misperceptions and a greater failure to detect bistable percepts correctly compared to HC. Further, the number of misperceptions was also correlated with the severity of hallucinations. The findings from this study demonstrate that the BPP is a viable tool to measure misperceptions in DLB patients.

Genetic risk scores and hallucinations in patients with Parkinson disease

Objective

We examine the hypothesized overlap of genetic architecture for Alzheimer disease (AD), schizophrenia (SZ), and Parkinson disease (PD) through the use of polygenic risk scores (PRSs) with the occurrence of hallucinations in PD.

Methods

We used 2 population-based studies (ParkWest, Norway, and Parkinson's Environment and Gene, USA) providing us with 399 patients with PD with European ancestry and a PD diagnosis after age 55 years to assess the associations between 4 PRSs and hallucinations after 5 years of mean disease duration. Based on the existing genome-wide association study of other large consortia, 4 PRSs were created: one each using AD, SZ, and PD cohorts and another PRS for height, which served as a negative control.

Results

A higher prevalence of hallucinations was observed with each SD increase of the AD-PRS (odds ratio [OR]: 1.37, 95% confidence interval [CI]: 1.03-1.83). This effect was mainly driven by APOE (OR: 1.92, 95% CI: 1.14-3.22). In addition, a suggestive decrease and increase, respectively, in hallucination prevalence were observed with the SZ-PRS and the PD-PRS (OR: 0.77, 95% CI: 0.59-1.01; and OR: 1.29, 95% CI: 0.95-1.76, respectively). No association was observed with the height PRS.

Conclusions

These results suggest that mechanisms for hallucinations in PD may in part be driven by the same genetic architecture that leads to cognitive decline in AD, especially by APOE.

Hallucinations in Older Adults: A Practical Review

Older adults experience hallucinations in a variety of social, physical, and mental health contexts. Not everyone is open about these experiences, as hallucinations are surrounded with stigma. Hence, hallucinatory experiences in older individuals are often under-recognized. They are also commonly misunderstood by service providers, suggesting that there is significant scope for improvement in the training and practice of professionals working with this age group. The aim of the present article is to increase knowledge about hallucinations in older adults and provide a practical resource for the health and aged-care workforce. Specifically, we provide a concise narrative review and critique of (1) workforce competency and training issues, (2) assessment tools, and (3) current treatments and management guidelines. We conclude with a brief summary including suggestions for service and training providers and future research.

Prevalence and characteristics of multi-modal hallucinations in people with psychosis who experience visual hallucinations

Hallucinations can occur in single or multiple sensory modalities. Historically, greater attention has been paid to single sensory modality experiences with a comparative neglect of hallucinations that occur across two or more sensory modalities (multi-modal hallucinations). With growing evidence suggesting that visual hallucinations may be experienced along with other hallucinations, this study aimed to explore multi-modal hallucinations in a sample of people with psychotic disorders who reported visual hallucinations (n = 22). No participants reported just visual hallucinations i.e. all reported related or unrelated auditory hallucinations. Twenty-one participants reported multi-modal hallucinations that were serial in nature, whereby they saw visual hallucinations and heard unrelated auditory hallucinations at other times. Nineteen people out of the twenty two also reported simultaneous multi-modal hallucinations, with the most common being an image that talked to and touched them. Multi-modal related and simultaneous hallucinations appeared to be associated with greater conviction that the experiences were real, and greater distress. Theoretical and clinical implications of multi-modal hallucinations are discussed.