Investigation of structural brain changes in Charles Bonnet Syndrome

Firbank, Michael J., da Silva Morgan, Katrina, Collerton, Daniel, Elder, Greg, Parikh, Jehill, Olsen, Kirsty, Schumacher, Julia, Ffytche, Dominic H. and Taylor, John-Paul (2022) Investigation of structural brain changes in Charles Bonnet Syndrome. NeuroImage: Clinical, 35. p. 103041. ISSN 2213-1582

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Official URL: https://doi.org/10.1016/j.nicl.2022.103041

Abstract

Background and objectives
In Charles Bonnet Syndrome (CBS), visual hallucinations (VH) are experienced by people with sight loss due to eye disease or lesional damage to early visual pathways. The aim of this cross-sectional study was to investigate structural brain changes using magnetic resonance imaging (MRI) in CBS.

Methods
Sixteen CBS patients, 17 with eye disease but no VH, and 19 normally sighted people took part. Participants were imaged on a 3T scanner, with 1 mm resolution T1 weighted structural imaging, and diffusion tensor imaging with 64 diffusion directions.

Results
The three groups were well matched for age, sex and cognitive scores (MMSE). The two eye disease groups were matched on visual acuity. Compared to the sighted controls, we found reduced grey matter in the occipital cortex in both eye disease groups. We also found reductions of fractional anisotropy and increased diffusivity in widespread areas, including occipital tracts, the corpus callosum, and the anterior thalamic radiation. We did not find any significant differences between the eye disease participants with VH versus without VH, but did observe a negative association between hippocampal volume and VH severity in the CBS group.

Discussion
Our findings suggest that although there are cortical and subcortical effects associated with sight loss, structural changes do not explain the occurrence of VHs. CBS may relate instead to connectivity or excitability changes in brain networks linked to vision.

Item Type: Article
Additional Information: Funding information: This work was supported by the Macular Society (BH152932), Esme’s Umbrella / Fight for Sight, Thomas Pocklington Trust Small Grant Award (24TP172), and the NIHR Newcastle Biomedical Research Centre (BRC) based at Newcastle upon Tyne Hospitals NHS Foundation Trust and Newcastle University and the SLaM Mental Health BRC. DFF, DC, KO, and J-PT were supported by NIHR Programme Grants for Applied Research (RP‐PG‐0610‐10100 - SHAPED). The views expressed are those of the authors and not necessarily those of the NIHR or the Department of Health and Social Care.
Uncontrolled Keywords: Charles Bonnet Syndrome, Visual hallucinations, Eye disease, MRI
Subjects: B100 Anatomy, Physiology and Pathology
C800 Psychology
Department: Faculties > Health and Life Sciences > Psychology
Depositing User: Elena Carlaw
Date Deposited: 09 May 2022 11:41
Last Modified: 16 May 2022 08:15
URI: http://nrl.northumbria.ac.uk/id/eprint/49069

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