Investigation of structural brain changes in Charles Bonnet Syndrome

Firbank, Michael; Morgan, K D; Collerton, Daniel; Elder, Greg J.; Parikh, Jehill; Olsen, Kirsty; Schumacher, Julia; Ffytche, Dominic; Taylor, John‐Paul

doi:10.1016/j.nicl.2022.103041

Cited by 4 publications

(2 citation statements)

References 53 publications

(71 reference statements)

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“…In addition to the tDCS trial, the study included a pilot phase to identify optimal tDCS stimulation parameters in a separate group of CBS participants and structural and functional imaging studies comparing CBS with control eye disease patients, reported elsewhere. 19…”

Section: Participantsmentioning

confidence: 99%

“…29,30 Bilateral reductions in both gray and white matter are associated with eye disease 31,32 and were also found in a structural imaging study of the participants reported here. 19 It is possible the effect of tDCS may have been impacted by these cortical changes, potentially explaining intersubject variation in VH improvement following tDCS and intersubject variation of EEG measures. Another factor to consider is the focal nature of the stimulation in this study, which used smaller electrodes with a less diffuse field of stimulation than previous similar studies.…”

Section: Mechanism Of Actionmentioning

confidence: 99%

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Transcranial Direct Current Stimulation in the Treatment of Visual Hallucinations in Charles Bonnet Syndrome

et al. 2022

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Section: Participantsmentioning

confidence: 99%

Section: Mechanism Of Actionmentioning

confidence: 99%

Transcranial Direct Current Stimulation in the Treatment of Visual Hallucinations in Charles Bonnet Syndrome

et al. 2022

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Neurochemistry and functional connectivity in the brain of people with Charles Bonnet syndrome

Bridge,

Wyllie,

Kay

et al. 2024

Ophthalmol Eye Dis

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Background: Charles Bonnet syndrome (CBS) is a condition in which people with vision loss experience complex visual hallucinations. These complex visual hallucinations may be caused by increased excitability in the visual cortex that are present in some people with vision loss but not others. Objectives: We aimed to evaluate the association between γ-aminobutyric acid (GABA) in the visual cortex and CBS. We also tested the relationship among visually evoked responses, functional connectivity, and CBS. Design: This is a prospective, case-controlled, cross-sectional observational study. Methods: We applied 3-Tesla magnetic resonance spectroscopy, as well as task-based and resting state (RS) connectivity functional magnetic resonance imaging in six participants with CBS and six controls without CBS. GABA+ was measured in the early visual cortex (EVC) and in the lateral occipital cortex (LOC). Participants also completed visual acuity and cognitive tests, and the North-East Visual Hallucinations Interview. Results: The two groups were well-matched for age, gender, visual acuity and cognitive scores. There was no difference in GABA+ levels between groups in the visual cortex. Most participants showed the expected blood oxygenation level dependent (BOLD) activation to images of objects and the phase-scrambled control. Using a fixed effects analysis, we found that BOLD activation was greater in participants with CBS compared to controls. Analysis of RS connectivity with LOC and EVC showed little difference between groups. A fixed effects analysis showed a correlation between the extent of functional connectivity with LOC and hallucination strength. Conclusion: Overall, our results provide no strong evidence for an association between GABAergic inhibition in the visual cortex and CBS. We only found subtle differences in visual function and connectivity between groups. These findings suggest that the neurochemistry and visual connectivity for people with Charles Bonnet hallucinations are comparable to a sight loss population. Differences between groups may emerge when investigating subtle and transient changes that occur at the time of visual hallucinations.

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The experiences of visually impaired military veterans with Charles Bonnet syndrome

Dave,

Jones,

Lee

et al. 2024

Ophthalmol Eye Dis

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Background: Charles Bonnet syndrome (CBS) refers to the experience of visual hallucinations occurring secondary to sight loss. Although there is an increasing amount of research on this phenomenon, CBS remains a lesser-known outcome of visual impairment, with limited research into the impact on the patient. Objectives: To explore the experiences and opinions of visually impaired military veterans with CBS regarding the impact of visual hallucinations. Design: Semi-structured qualitative interviews. Methods: Forty-six telephone interviews were conducted with members of Blind Veterans UK, a charity for visually impaired ex-service men and women. One-hundred and fifteen individuals at the charity with CBS were identified and invited to a semi-structured interview (participation rate – 40%). Qualitative data was transcribed and analysed using thematic analysis. Results: Four overarching themes were identified: (1) impact of CBS (2) understanding and management of CBS (3) awareness of CBS (4) recommendations. Negative impact of CBS included feelings of fear, annoyance and disruptions to daily life and quality of life. Negative appraisal of CBS was not necessarily related to negative hallucination content. Participants expressed the value of increased awareness amongst patients and health care professionals. Knowledge and understanding of CBS provided reassurance and was considered an effective strategy to mitigate the negative impact of the condition. Conclusion: Regardless of hallucination content, CBS has a substantial impact on the lives of people with visual impairment. Increased awareness and information can help to support individuals to manage their CBS more effectively. However, the findings from this study cannot be generalized to people without a military background so further research is required to understand and optimize support for military veterans and civilians with CBS.

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Investigation of structural brain changes in Charles Bonnet Syndrome

Cited by 4 publications

References 53 publications

Transcranial Direct Current Stimulation in the Treatment of Visual Hallucinations in Charles Bonnet Syndrome

Transcranial Direct Current Stimulation in the Treatment of Visual Hallucinations in Charles Bonnet Syndrome

Neurochemistry and functional connectivity in the brain of people with Charles Bonnet syndrome

The experiences of visually impaired military veterans with Charles Bonnet syndrome

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