City Research Online

Abstract

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.

Publication Type:	Article
Additional Information:	© 2026 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) and the copyright owner(s) 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.
Publisher Keywords:	CBS, alpha waves, visual brain, electroencephalography, visual impairment
Subjects:	R Medicine > RE Ophthalmology
Departments:	School of Health & Medical Sciences School of Health & Medical Sciences > Department of Optometry & Visual Science
SWORD Depositor:	Symplectic Administrator

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