UNASSIGNED: This systematic review and meta-analysis review the literature regarding the prevalence of visual hallucinations in patients with first-episode psychosis. Previous reviews have focused on the prevalence of visual hallucinations in a general psychosis population, highlighting a weighted prevalence of 27%. However, no reviews have focused specifically on the experiences of those with a first episode of psychosis. Understanding \"first-episode\" experiences is crucial, as intervention during this \"critical period\" is thought to define long-term outcome. Therefore, it is important that the prevalence of different symptoms during this period is accurately represented.
UNASSIGNED: Systematic searches yielded 15 studies to be meta-analyzed. Information to calculate event rates was extracted. Studies were rated for their methodological quality using a risk of bias tool. The quality of included studies varied; generalizability bias was the domain with the most risk of bias.
UNASSIGNED: Prevalence rates were synthesized from the 15 papers included in the final analysis, which generated a weighted prevalence estimate of 33% of people with first-episode psychosis experiencing visual hallucinations. Subgroup analyses were carried out and did not demonstrate significant associations.
UNASSIGNED: This meta-analysis provides a robust estimate of 33% for the prevalence of visual hallucinations in first-episode psychosis; highlighting that visual hallucinations are relatively common experiences.

暂无摘要。

N, N-dimethyltryptamine (DMT) is a psychedelic tryptamine acting on 5-HT2A serotonin receptors, which is associated with intense visual hallucinatory phenomena and perceptual changes such as distortions in visual space. The neural underpinnings of these effects remain unknown. We hypothesised that changes in population receptive field (pRF) properties in the primary visual cortex (V1) might underlie visual perceptual experience. We tested this hypothesis using magnetic resonance imaging (MRI) in a within-subject design. We used a technique called pRF mapping, which measures neural population visual response properties and retinotopic maps in early visual areas. We show that in the presence of visual effects, as documented by the Hallucinogen Rating Scale (HRS), the mean pRF sizes in V1 significantly increase in the peripheral visual field for active condition (inhaled DMT) compared to the control. Eye and head movement differences were absent across conditions. This evidence for short-term effects of DMT in pRF may explain perceptual distortions induced by psychedelics such as field blurring, tunnel vision (peripheral vision becoming blurred while central vision remains sharp) and the enlargement of nearby visual space, particularly at the visual locations surrounding the fovea. Our findings are also consistent with a mechanistic framework whereby gain control of ongoing and evoked activity in the visual cortex is controlled by activation of 5-HT2A receptors.

UNASSIGNED: Prior research on the Noise Pareidolia Test (NPT) has demonstrated its clinical utility in detecting patients with mild cognitive impairment and dementia due to Lewy Body Disease (LBD). However, few studies to date have investigated the neuropsychological factors underlying pareidolia errors on the NPT across the clinical spectrum of LBD. Furthermore, to our knowledge, no research has examined the relationship between cortical thickness using MRI data and NPT subscores. As such, this study sought to explore the neuropsychological and neuroanatomical factors influencing performance on the NPT utilizing the National Alzheimer\'s Coordinating Center Lewy Body Dementia Module.
UNASSIGNED: Our sample included participants with normal cognition (NC; n = 56), LBD with mild cognitive impairment (LBD-MCI; n = 97), and LBD with dementia (LBD-Dementia; n = 94). Archival data from NACC were retrospectively analyzed for group differences in neuropsychological test scores and cognitive and psychiatric predictors of NPT scores. Clinicoradiological correlates between NPT subscores and a small subsample of the above LBD participants were also examined.
UNASSIGNED: Analyses revealed significant differences in NPT scores among groups. Regression analysis demonstrated that dementia severity, attention, and visuospatial processing contributed approximately 24% of NPT performance in LBD groups. Clinicoradiological analysis suggests a potential contribution of the right fusiform gyrus, but not the inferior occipital gyrus, to NPT pareidolia error scores.
UNASSIGNED: Our findings highlight the interplay of attention and visuoperceptual functions in complex pareidolia in LBD. Further investigation is needed to refine the utility of NPT scores in clinical settings, including identifying patients at risk for visual illusions and hallucinations.

Visual hallucinations (VH) can increase the burden of disease for both patients with Parkinson\'s disease (PD) and their caregivers. Multiple neurotransmitters have been implicated in the neuropathology of VH, which provide targets for treatment and prevention. In this study, we assessed the association between cholinergic denervation and VH in PD in vivo, using PET imaging of the cholinergic system. A total of 38 PD patients participated in this study. A group of 10 healthy subjects, matched for age, sex and education, was included for comparison. None of the participants used cholinergic drugs. Thirteen patients who had experienced VH in the past month (VH+) were compared to 20 patients who had never experienced VH in their lives (VH-). Cholinergic system integrity was assessed with PET imaging using [18F]fluoroethoxybenzovesamicol ([18F]FEOBV) as the tracer. We assessed the differences in tracer uptake between groups by cluster-based analysis and by analysis of predefined regions of interest (ROIs) consisting of the ventral visual stream, the dorsal attentional network, the ventral attentional network and the lateral geniculate nucleus and mediodorsal nucleus of the thalamus. The PD group (n=38) showed an extensive pattern of decreased tracer uptake throughout the brain, compared to the controls (n=10). Within the PD group, the VH+ group (n=13) showed a cluster of decreased tracer uptake compared to the VH- group (n=20), which covered most of the left ventral visual stream and extended towards superior temporal areas. These results were mirrored in the ROI-based analysis, where the VH+ group showed the strongest deficits in the left inferior temporal gyrus and the left superior temporal gyrus, compared to the VH- group. VH in PD are associated with a marked cholinergic deficiency in the left ventral visual stream and the left superior temporal lobe, in addition to an extensive global cholinergic denervation in the general PD population.

Introduction: We report an epileptic patient who experienced hallucinatory visual experiences of autobiographical memories from her past. These visual experiences were confined to the lower left quadrant of her visual field.Methods: We carried out a single-case study that used brain-imaging, EEG and behavioural methods to study this patient.Results: We found that this patient had an incomplete left inferior homonymous quadrantanopia due to a lesion of right occipital cortex, and also that she showed neurological abnormalities in right temporal cortex, a region that is part of the brain\'s autobiographical-memory circuit.Conclusion: We attribute the occurrence of this patient\'s autobiographical-memory hallucinations to the combination of degraded visual input to right temporal cortex plus hyperexcitability of that region.

Identifying the coexistence of Lewy body (LB) pathology with Alzheimer\'s disease (AD) in clinical practice is important in the era of anti-amyloid-β antibody therapy. However, few studies have predicted the presence of comorbid LB pathology with AD using indicative biomarkers of dementia with Lewy bodies or by collecting detailed clinical symptoms. We report the clinical progression of a 67-year-old patient diagnosed with AD who developed rapid eye movement sleep disorder-like symptoms and transient visual hallucinations 10 years after AD onset and was considered to have comorbid LB pathology based on imaging indicative biomarkers of dementia with Lewy bodies.

BACKGROUND: Visual hallucinations (VH) are more common than previously thought and are linked to higher levels of distress and disability in people with a psychotic illness. Despite this, scant attention has been given to VHs in the clinical literature, and the few therapy case series of cognitive behavioural therapy (CBT) published to date have not demonstrated reliable change. In other areas of clinical research, problematic mental imagery has been found to be more strongly related to negative affect in psychological disorders than negative linguistic thinking, and imagery focused techniques have commonly been found to improve the outcomes in CBT trials. Given VHs have many similarities with visual mental imagery and many of the distressing beliefs associated with VHs targeted in CBT are maintained by accompanying mental imagery (i.e., imaging a hallucinated figure attacking them), it seems plausible that an imagery-focused approach to treating VHs may be most effective.
METHODS: The current study is a multiple baseline case series (N = 11) of a 10-session imagery-focused therapy for VH in a transdiagnostic sample.
RESULTS: The study had good attendance and feedback, no adverse events and only one [seemly unrelated] drop-out, suggesting good feasibility, safety and acceptability. The majority of clients reported reduction on both full-scale measures (administered at 3 baselines, midtherapy, posttherapy and 3-month follow-up) and weekly measures of VH severity and distress, ranging from medium to large effect sizes.
CONCLUSIONS: The case series suggests that an imagery-focused approach to treating VHs may be beneficial, with a recommendation for more rigorous clinical trials to follow.

Psychedelics like LSD (Lysergic acid diethylamide) and psilocybin are known to modulate perceptual modalities due to the activation of mostly serotonin receptors in specific cortical (e.g., visual cortex) and subcortical (e.g., thalamus) regions of the brain. In the visual domain, these psychedelic modulations often result in peculiar disturbances of viewed objects and light and sometimes even in hallucinations of non-existent environments, objects, and creatures. Although the underlying processes are poorly understood, research conducted over the past twenty years on the subjective experience of psychedelics details theories that attempt to explain these perceptual alterations due to a disruption of communication between cortical and subcortical regions. However, rare medical conditions in the visual system like Charles Bonnet syndrome that cause perceptual distortions may shed new light on the additional importance of the retinofugal pathway in psychedelic subjective experiences. Interneurons in the retina called amacrine cells could be the first site of visual psychedelic modulation and aid in disrupting the hierarchical structure of how humans perceive visual information. This paper presents an understanding of how the retinofugal pathway communicates and modulates visual information in psychedelic and clinical conditions. Therefore, we elucidate a new theory of psychedelic modulation in the retinofugal pathway.

UNASSIGNED: Charles Bonnet syndrome (CBS) is characterized by visual hallucinations occurring in people with visual impairment. CBS can negatively impact psychological well-being, and the COVID-19 pandemic period was associated with an exacerbation of symptoms.
UNASSIGNED: To compare clinical practice patterns and reporting of CBS at a tertiary eye care center between an interval prior to the COVID-19 pandemic and an interval during the pandemic.
UNASSIGNED: Retrospective chart review.
UNASSIGNED: A search of electronic medical records for all suspected CBS cases was conducted between 1 March 2019 and 29 February 2020 (prior pandemic interval) and between 1 September 2020 and 29 August 2021 (peri-pandemic interval). Data retrieved from records included patient demographics, visual acuity at the time of CBS onset, type of hallucinations, reporting healthcare professional, management strategies and patient-reported impact of hallucinations.
UNASSIGNED: In total, 223 appointments referred to CBS in 156 patients at the prior interval, while 239 appointments referred to CBS in 155 patients at the peri-pandemic interval, representing 0.07% and 0.09% of all hospital attendance, respectively. Clinical subspecialty where CBS was most commonly reported was medical retina, and a greater proportion of patients at both time intervals were female. Types of hallucinations, management strategies and patient-reported impact were seldom reported, although documentation improved at the latter interval.
UNASSIGNED: Practice patterns and patient characteristics were similar between the two intervals; however, subtle differences suggest a growing awareness of CBS. Targeted interventions in high-burden clinical subspecialties may encourage reporting and improve documentation of CBS.