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BRIEF RESEARCH REPORT article

Front. Neurol.

Sec. Neuro-Ophthalmology

This article is part of the Research TopicAdvances in Understanding Visual Disorders Linked to Cortical DysfunctionView all 12 articles

EEG Changes Associated with Hallucinations Caused by Charles Bonnet Syndrome

Provisionally accepted
Jasleen Kaur JollyJasleen Kaur Jolly1,2,3*Natalie AssafNatalie Assaf2Bethany E HigginsBethany E Higgins2,4Jane Elizabeth AspellJane Elizabeth Aspell5Elizabeth MichaelElizabeth Michael6
  • 1Department of Optometry and Vision Sciences, Melbourne School of Health Sciences, Faculty of Medicine, Dentistry and Health Sciences, University of Melbourne, Carlton, Australia
  • 2Anglia Ruskin University Vision and Eye Research Institute, Cambridge, United Kingdom
  • 3Jolly Vision Science, Cambridge, United Kingdom
  • 4City St George's University of London Department of Optometry and Visual Science, London, United Kingdom
  • 5Anglia Ruskin University School of Psychology and Sport Science, Cambridge, United Kingdom
  • 6MRC Cognition and Brain Sciences Unit, Cambridge, United Kingdom

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Charles Bonnet Syndrome (CBS) is characterised by the presence of visual hallucinations following visual loss in many patients. The neuropathophysiology of CBS is poorly understood. We used electroencephalography (EEG) in individuals with frequent hallucinations in order to identify changes in neural activity that co-occur with hallucination onset. We found reduced α power in occipital electrodes at the onset of the hallucinations compared to offset (p < 0.05), suggesting that intermittent periods of low endogenous alpha may create the neural conditions for hallucination to emerge in CBS patients. This is the first group study that shows a repeatable marker of brain activity changes in CBS that occur either at the onset or just prior to the onset of the hallucination. This offers important implications for both research and clinical practice. It could aid in early detection and prediction of hallucination onset and improve our understanding of the neural mechanisms underlying CBS. It also may help reduce stigma around the condition by validating the patient experience through measurable brain changes.

Keywords: CBS, alpha waves, visual brain, Electroencephalography, visual impairment

Received: 01 Sep 2025; Accepted: 21 Nov 2025.

Copyright: © 2025 Jolly, Assaf, Higgins, Aspell and Michael. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence: Jasleen Kaur Jolly, jasleen.jolly@unimelb.edu.au

Disclaimer: All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article or claim that may be made by its manufacturer is not guaranteed or endorsed by the publisher.

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