Charles Bonnet Syndrome Eye Diseases
Conditions
Interventions
Randomisation, blinding & unblinding
Randomised lists will be generated by a researcher/statistician who is independent and not associated with the study and will be contained in a set
Sponsors
Northumberland Tyne & Wear NHS Trust
Eligibility
Sex/Gender
All
Inclusion criteria
Inclusion criteria: All participants: 1. Age >18, either sex 2. Provision of written informed consent 3. MMSE-blind >24 4. Absence of any concurrent major psychiatric illness (e.g. major depression) or dementia 5. Absence of severe physical illness or co-morbidity that may limit ability to fully participate in study 6. Sufficient English to allow assessment scales and cognitive testing Charles Bonnet Syndrome: 1. Meet the diagnostic criteria of CBS: Cognitively intact, having complex visual hallucinations (with no hallucinations in other modalities or delusions), full insight into the unreality of these, and presence of eye disease sufficient to cause visual impairment 2. Evidence of persistent and recurrent episodes of visual hallucinations determined to be of stable frequency with the expectation of at least one hallucination per day Control (eye disease): 1. Presence of eye disease sufficient to cause visual impairment 2. No prior history of visual hallucinations
Exclusion criteria
Exclusion criteria: All participants: 1. Skin allergies or sensitivities to electrode gels or any significant dermatological/scalp disease 2. Past history of excess alcohol intake 3. Past history of other neurological illness including, but not limited to, stroke, intracerebral pathology, and epilepsy 4. Metal or electronic implants (including pacemakers) which might be affected by strong magnetic fields (occurring in TMS or MR component of the study) or electrical currents (tDCS component) Charles Bonnet Syndrome: 1. Psychotropic and other medications which may significantly interfere with cognitive testing and tDCS efficacy (including high dose antipsychotics, dopamine agonists, sedative antidepressants, benzodiazepines except when in low dose and used as hypnotics, and centrally acting anticholinergic drugs) 2. Evidence for Lewy body symptoms and signs which may cast doubt on a CBS diagnosis (i.e. REM sleep disorder). Control (eye disease): 1. Past history of visual hallucinations
Design outcomes
Primary
| Measure | Time frame |
|---|---|
| The acute benefits of tDCS on visual hallucinations at Day 5 after active stimulation in comparison to placebo. The effect that stimulation has on visual hallucinations will be assessed in terms of duration, severity, frequency and emotional impact of the hallucinations across the four day stimulation period, using the North East Visual Hallucinations Index (NEVHI) adapted for use in CBS patients, and the Neuropsychiatric Inventory (NPI) hallucinations subscale score. | — |
Secondary
| Measure | Time frame |
|---|---|
| All measured on day 1 (baseline) and day 5 of the trial. This will happen on both treatment weeks: 1. Visual function including: 1.1. Visual acuity (Freiburg test) 1.2. Contrast sensitivity (Freiburg contrast test) 1.3. Visual field (tangent screen) 1.4. Visual distortion (Amsler chart) 1.5. Higher visual function screening 2. Excitability in the visual cortex measured using the repeat phosphene excitability measure 3. Resting state EEG, including alpha band and gamma activity 4. Visual cortical function and metabolic GABA/glutamate levels Baseline data collected from EEGs, including alpha and gamma activity, TMS phosphene thresholds, structural, cortical function, and metabolic GABA/glutamate levels, will also be compared between patients with CBS and the control group. | — |
Countries
England, United Kingdom
Contacts
Public ContactKirsty Olsen
Outcome results
None listed