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.

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

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.

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.

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.

Charles Bonnet syndrome (CBS) is characterized by the presence of visual hallucinations, generally complex, which occurs in patients with alterations in the visual pathway. The majority of affected patients are elderly. It appears in 15% of people with visual loss, predominantly in the 80-year-old female gender.

To present a clinical case of a patient with visual hallucinations and a possible diagnosis of Charles Bonnet syndrome. Highlight the importance of an adequate differential diagnosis.

Bibliographic review of the treatment and diagnosis of CBS, from articles published in the last 5 years in Pubmed.

Woman, 80 years old. No ophthalmological history except those associated with advanced age. She goes to the emergency room due to the presence of visual hallucinosis, in the form of “television presenters” of whom she makes partial criticism, being aware most of the time of their unreality. Hallucinations are not accompanied by anxiety or significant affective repercussions. Discarded delirium, intoxication by substances or drugs that cause the condition. Currently under follow-up to rule out other causes.

The diagnosis of SCB requires a multidisciplinary approach between neurologists, psychiatrists and ophthalmologists in order to avoid erroneous diagnoses. The differential diagnosis should be made with pathologies such as Lewy body dementia, Parkinson’s disease, delirium, substance intoxication, migraine aura, and metabolic encephalopathy, among others. It is important to involve the family in the treatment of the syndrome to reinforce the recognition of the unreality of these hallucinations in the patients. Antipsychotic treatment can be effective only if the condition is extremely distressing.

Using as a starting point a clinical case, the authors performed a literature review to clarify the relationship between visual hallucinations and treatment with ropinirole.

Analysis of the patient's clinical process and brief review of the latest available literature on the subject, published in PubMed/Medline databases.

Female patient, 89 years old, without psychiatric illness, brought to the emergency room by visual hallucinations, in the past 3 days “I see red, blue and green spots and roses on your sweater and a lot of flowers on that lady's blouse”sic. She recognised them as unreal (pseudo hallucinations) “no, nothing is there. It's from my eyes. I am fine of the head”sic. She has a personal history of glaucoma for decades, and restless legs syndrome for about 1 year, medicated with ropinirole. Adherence to therapeutic has been explored and it was found that she has been increasing, progressively and by its own initiative, the dose of ropinirole. She claims to be currently taking two pills of 8 mg twice daily (the recommended daily dose is 24 mg).

Studies indicate that the incidence of hallucinations during the treatment of RLS with ropinirole is less than 1%, which can be justified by its high affinity for D3 receivers compared to D2 receivers. However, it is also known that the over-stimulation of dopamine receptors (by overdose or rapid titration) can cause hallucinations, which may have been the cause of the patient's clinical condition. This clinical case also allows to alert for the importance of excluding organic causes in the diagnosis of visual hallucinations.

Non-motor features of Parkinson's disease (PD) and dementia with Lewy bodies (DLB), such as auditory hallucinations (AH), contribute to disease burden but are not well understood.

Systematic review and random-effects meta-analyses of studies reporting AH associated with PD or DLB. Prevalence of visual hallucinations (VH) in identified studies meeting eligibility criteria were included in meta-analyses, facilitating comparison with AH. Synthesis of qualitative descriptions of AH was performed. PubMed, Web of Science and Scopus databases were searched for primary journal articles, written in English, published from 1970 to 2017. Studies reporting AH prevalence in PD or DLB were screened using PRISMA methods.

Searches identified 4542 unique studies for consideration, of which, 26 met inclusion criteria. AH pooled prevalence in PD was estimated to be 8.9% [95% confidence interval (CI) 5.3–14.5], while in DLB was estimated to be 30.8% (±23.4 to 39.3). Verbal hallucinations, perceived as originating outside the head, were the most common form of AH. Non-verbal AH were also common while musical AH were rare. VH were more prevalent, with an estimated pooled prevalence in PD of 28.2% (±19.1 to 39.5), while in DLB they were estimated to be 61.8% (±49.1 to 73.0). Meta-regression determined that the use of validated methodologies to identify hallucinations produced higher prevalence estimates.

AH and VH present in a substantial proportion of PD and DLB cases, with VH reported more frequently in both conditions. Both AH and VH are more prevalent in DLB than PD. There is a need for standardised use of validated methods to detect and monitor hallucinations.

Recent evidence shows that the serotonin 2A receptor (5-hydroxytryptamine2A receptor, 5-HT2AR) is critically involved in the formation of visual hallucinations and cognitive impairments in lysergic acid diethylamide (LSD)-induced states and neuropsychiatric diseases. However, the interaction between 5-HT2AR activation, cognitive impairments and visual hallucinations is still poorly understood. This study explored the effect of 5-HT2AR activation on response inhibition neural networks in healthy subjects by using LSD and further tested whether brain activation during response inhibition under LSD exposure was related to LSD-induced visual hallucinations.

In a double-blind, randomized, placebo-controlled, cross-over study, LSD (100 µg) and placebo were administered to 18 healthy subjects. Response inhibition was assessed using a functional magnetic resonance imaging Go/No-Go task. LSD-induced visual hallucinations were measured using the 5 Dimensions of Altered States of Consciousness (5D-ASC) questionnaire.

Relative to placebo, LSD administration impaired inhibitory performance and reduced brain activation in the right middle temporal gyrus, superior/middle/inferior frontal gyrus and anterior cingulate cortex and in the left superior frontal and postcentral gyrus and cerebellum. Parahippocampal activation during response inhibition was differently related to inhibitory performance after placebo and LSD administration. Finally, activation in the left superior frontal gyrus under LSD exposure was negatively related to LSD-induced cognitive impairments and visual imagery.

Our findings show that 5-HT2AR activation by LSD leads to a hippocampal–prefrontal cortex-mediated breakdown of inhibitory processing, which might subsequently promote the formation of LSD-induced visual imageries. These findings help to better understand the neuropsychopharmacological mechanisms of visual hallucinations in LSD-induced states and neuropsychiatric disorders.

Little is known about visual hallucinations (VH) in psychosis. We investigated the prevalence and the role of bottom-up and top-down processing in VH. The prevailing view is that VH are probably related to altered top-down processing, rather than to distorted bottom-up processing. Conversely, VH in Parkinson's disease are associated with impaired visual perception and attention, as proposed by the Perception and Attention Deficit (PAD) model. Auditory hallucinations (AH) in psychosis, however, are thought to be related to increased attention.

Our retrospective database study included 1119 patients with non-affective psychosis and 586 controls. The Community Assessment of Psychic Experiences established the VH rate. Scores on visual perception tests [Degraded Facial Affect Recognition (DFAR), Benton Facial Recognition Task] and attention tests [Response Set-shifting Task, Continuous Performance Test-HQ (CPT-HQ)] were compared between 75 VH patients, 706 non-VH patients and 485 non-VH controls.

The lifetime VH rate was 37%. The patient groups performed similarly on cognitive tasks; both groups showed worse perception (DFAR) than controls. Non-VH patients showed worse attention (CPT-HQ) than controls, whereas VH patients did not perform differently.

We did not find significant VH-related impairments in bottom-up processing or direct top-down alterations. However, the results suggest a relatively spared attentional performance in VH patients, whereas face perception and processing speed were equally impaired in both patient groups relative to controls. This would match better with the increased attention hypothesis than with the PAD model. Our finding that VH frequently co-occur with AH may support an increased attention-induced ‘hallucination proneness’.

Visual hallucinations are a common phenomenon, among the older adult population. They can be functional or organic in aetiology. However, new onset visual hallucinations in this population are strongly suggestive of organic brain disease. Visual impairment, cerebrovascular disease and Parkinson’s disease are three causes of visual hallucinations, considered in this case series. The evidence in the literature, for the treatment of these conditions is scant at best. There is a paucity of randomised controlled trials available concerning possible therapeutic options.

We describe three case reports of visual hallucinations due to diverse underlying aetiologies. We then discuss the aetiologies of visual hallucinations in general and then in these particular cases and finally include results of a literature search examining the available evidence for any therapeutic options proposed.

Our three cases have different, underlying aetiologies. One case is of Charles Bonnet syndrome. The next is of visual hallucinations associated with vascular dementia. The final case is of visual hallucinations associated with Parkinson’s disease. The first two cases are of particular interest due to the efficacy of Amisulpride in both clinical scenarios.

Visual hallucinations are a common phenomenon in the elderly population

They can be due to a myriad of underlying causes. There are a number of neurochemical factors and neuroanatomical structures implicated. The evidence for psychopharmacological interventions is scanty. Randomised controlled trials are lacking in the area. An interesting finding in this case series, was of the clinical utility of Amisulpiride. Given this agent’s unique psychopharmacological profile it is possible that it may be efficacious in other cases of visual hallucinations associated with particular neurochemical factors.

Charles Bonnet syndrome (CBS) is defined as complex persistent visual hallucinations in the absence of mental disorder. It is common in conditions causing significant visual impairment. Many authors advise reassurance, considering the condition benign. However, others have suggested that CBS may in some patients represent the early stages of dementia. This review seeks to systematically examine the evidence for any link between CBS and cognitive impairment.

Literature search using OVID Medline, PsychINFO, and Embase.

Three studies where cognitive functioning was the primary focus of the research were found. All were small, did not properly apply diagnostic criteria, and reported conflicting results. Eight other studies commented on cognitive functioning, but none used tests sufficiently sensitive to detect changes seen in early dementia. One hundred and thirty four case reports were scrutinized, and reports found of 16 patients with CBS where dementia emerged. High rates of partial insight at diagnosis of CBS were seen in these patients.

There have been no adequately powered studies, using accepted diagnostic criteria, where changes in cognitive functioning were the primary outcome. Existing studies are of limited methodological quality and allow no conclusion regarding a relationship between cognitive impairment and CBS to be reached. Numerous case reports of dementia developing in patients with CBS and partial insight raise the possibility of a link between these conditions. There is a clear need for properly constructed studies to investigate this.