Participants experiencing hallucinations were predominantly female with a mean age of 77.7 years. A group of 30 non-hallucinating participants was chosen for comparison of demographic data. They were then interviewed and asked demographic, general health and visual hallucination-related questions. Those who reported experiencing visual hallucinations were asked to participate in the project. Two hundred consecutive patients attending ophthalmology clinics aged more than 60 years with best-corrected visual acuity of 6/12 or less were screened for CBS. The aim of this study was to examine the prevalence and characteristics of CBS in the older aged, visually impaired population in Australia. The prevalence of the syndrome has been reported at 1-40% in Asia, Europe and North America. It most often occurs in older, visually impaired persons. Our findings suggest a reorganization of the functional connectivity between regions involved in self-awareness and in visual and salience processing in CBS that may contribute to the appearance of visual hallucinations.Ĭharles Bonnet Syndrome (CBS) is characterized by vivid, elaborate and recurrent visual hallucinations in psychologically normal people. In contrast, LB patients showed decreased functional connectivity compared to sighted controls between the DMN and the temporo-occipital fusiform gyrus, a region known to support hallucinations. The precuneus exhibited increased functional connectivity with the secondary visual cortex in the CBS patient compared to the controls. Reductions in cortical thickness in associative and multimodal cortices were observed in the CBS patient when comparing with LB subjects. Decreased grey matter volume was observed in the middle occipital gyrus and in the cuneus in the CBS patient, and in the middle occipital gyrus and in the lingual gyrus within LB subjects, compared to their respective control groups. We employed voxel-based morphometry and cortical thickness analyses to investigate alterations in grey matter characteristics, and rs-fMRI to study changes in functional brain connectivity. We aimed to investigate brain structural and functional changes in a patient with CBS, as compared with late blind (LB) and normally sighted subjects.
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Functional connectivity during resting-state functional magnetic resonance imaging (rs-fMRI without hallucinations) in CBS patients, has never been explored.
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Although studies suggested that visual hallucinations may be caused by brain damage in the visual system in CBS patients, alterations in specific brain regions in the occipital cortex have not been studied. Charles Bonnet syndrome (CBS) is a rare condition characterized by visual impairment associated with complex visual hallucinations in elderly people.