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Transcranial Direct Current Stimulation in the Treatment of Visual Hallucinations in Charles Bonnet Syndrome: A Randomized Placebo-Controlled Crossover Trial

Lookup NU author(s): Dr Kat Da Silva MorganORCiD, Julia SchumacherORCiD, Daniel Collerton, Dr Sean Colloby, Dr Greg Elder, Kirsty OlsenORCiD, Professor John-Paul TaylorORCiD



This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0).


© 2022 American Academy of Ophthalmology. Objective: To investigate the potential therapeutic benefits and tolerability of inhibitory transcranial direct current stimulation (tDCS) on the remediation of visual hallucinations in Charles Bonnet syndrome (CBS). Design: Randomized, double-masked, placebo-controlled crossover trial. Participants: Sixteen individuals diagnosed with CBS secondary to visual impairment caused by eye disease experiencing recurrent visual hallucinations. Intervention: All participants received 4 consecutive days of active and placebo cathodal stimulation (current density: 0.29 mA/cm2) to the visual cortex (Oz) over 2 defined treatment weeks, separated by a 4-week washout period. Main Outcome Measures: Ratings of visual hallucination frequency and duration following active and placebo stimulation, accounting for treatment order, using a 2 × 2 repeated-measures model. Secondary outcomes included impact ratings of visual hallucinations and electrophysiological measures. Results: When compared with placebo treatment, active inhibitory stimulation of visual cortex resulted in a significant reduction in the frequency of visual hallucinations measured by the North East Visual Hallucinations Interview, with a moderate-to-large effect size. Impact measures of visual hallucinations improved in both placebo and active conditions, suggesting support and education for CBS may have therapeutic benefits. Participants who demonstrated greater occipital excitability on electroencephalography assessment at the start of treatment were more likely to report a positive treatment response. Stimulation was found to be tolerable in all participants, with no significant adverse effects reported, including no deterioration in preexisting visual impairment. Conclusions: Findings indicate that inhibitory tDCS of visual cortex may reduce the frequency of visual hallucinations in people with CBS, particularly individuals who demonstrate greater occipital excitability prior to stimulation. tDCS may offer a feasible intervention option for CBS with no significant side effects, warranting larger-scale clinical trials to further characterize its efficacy.

Publication metadata

Author(s): daSilva Morgan K, Schumacher J, Collerton D, Colloby S, Elder GJ, Olsen K, ffytche DH, Taylor J-P

Publication type: Article

Publication status: Published

Journal: Ophthalmology

Year: 2022

Volume: 129

Issue: 12

Pages: 1368-1379

Print publication date: 01/12/2022

Online publication date: 09/07/2022

Acceptance date: 30/06/2022

Date deposited: 13/10/2022

ISSN (print): 0161-6420

ISSN (electronic): 1549-4713

Publisher: Elsevier Inc.


DOI: 10.1016/j.ophtha.2022.06.041

PubMed id: 35817197


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Funder referenceFunder name
NIHR Newcastle Biomedical Research Centre (BRC)