Neuroscience of Charles Bonnet Syndrome

NCT04777630 | Completed

• 2 other identifiers: PID15262IRAS No: 290078
• Study Type: observational
• Target: 16
• Locations: 1 country
• Sites: 2

Brief Summary

Charles Bonnet Syndrome (CBS) is a condition in which people experience complex visual hallucinations, such as 'Acrobats balancing on bicycles' or 'Spiders crossing meals'. The condition usually occurs in people who have significant vision loss due to eye disease. The aim of this project is to help understand how these hallucinations come about. In the healthy visual system, the eye provides input to a large area of the brain that performs the computations required to allow us to see the world. There are specialised brain regions responsible for processing of faces, objects, motion and colour. When the eye is no longer working, these parts of the brain lose their input and this may lead to abnormal activity. Not all people with eye disease and vision loss develop CBS, so the investigators will use magnetic resonance imaging (MRI) to compare the brains of people with and without the condition. In particular the investigators are interested in measuring the levels of chemicals in the visual areas of the brain to see whether they are disrupted in CBS, leading to the hallucinations. It is possible to measure how the different areas of the visual brain are connected together and see whether this is altered in CBS, perhaps with increases in the strength of connection between specialised areas. These measures will be related to questionnaires about hallucinations and vision. This will be done by comparing low vision who experience Charles Bonnet visual hallucinations compared to low vision patients who do not have hallucinations. Assessments will take place at the Wellcome Centre for Integrative Imaging (WIN) based at the John Radcliffe Hospital. The study will provide insight into the role of the brain in generating CBS hallucinations, helping us to design a larger study and eventually to test whether there are interventions to help improve the condition.

Conditions

Charles Bonnet Syndrome

Keywords

charles bonnet; visual brain; hallucinations; low vision

Outcome Measures

Primary Outcomes (1)

• To assess changes in neurotransmitter balance across the visual cortex in patients with hallucinations compared to without hallucinations using MRSI.

  Comparison of neurotransmitter concentrations in different areas of the visual cortex. Correlation of these with the results of the questionnaires about hallucinations.

  1 day

Secondary Outcomes (2)

• To characterise the connectivity of visual areas across the brain in patients with hallucinations compared to without hallucinations (resting state and diffusion MRI).

  1 day

• To assess functional changes in the ventral visual stream in patients with hallucinations compared to without hallucinations (functional MRI).

  1 day

Study Arms (2)

Patients with low vision who experience Charles Bonnet hallucinations

No intervention, observation of neuroimaging and questionnaires

Diagnostic Test: None, neuroimaging

Patients with low vision who do not experience Charles Bonnet hallucinations

No intervention, observation of neuroimaging and questionnaires

Diagnostic Test: None, neuroimaging

Interventions

None, neuroimaging DIAGNOSTIC_TEST

Observation only to observe differences in neuroimaging

Patients with low vision who do not experience Charles Bonnet hallucinations; Patients with low vision who experience Charles Bonnet hallucinations

Eligibility Criteria

• Age: 18 Years - 70 Years
• Sex: all
• Healthy Volunteers: No
• Age Groups: Adult (18-64), Older Adult (65+)
• Sampling Method: Non-Probability Sample

Study Population

There will be two cohorts of participants. Cohort one will consist of low vision (as defined clinically) patients who experience visual hallucinations and cohort two will consist of low vision patients who do not experience visual hallucinations. Male and female adults will be included.

You may qualify if:

• Participant is willing \& able to give informed consent for participation in the study.
• Male or female, aged 18 - 70 years.
• Reduced vision.

You may not qualify if:

• Pre-existing amblyopia or squint.
• Insufficient understanding of written and verbal English to complete safety screening questionnaires.
• Pregnancy or trying to conceive.
• Other neurological problems which may confound the results, e.g. diagnosis of Parkinsons.
• Contraindication to MRI e.g. claustrophobia, presence of metallic implants, a pacemaker, recent surgery etc.
• MR Spectroscopy contraindications e.g. use of antidepressants or antipsychotic medication, frequent cigarette and alcohol consumption. This is defined as no more than one cigarette per day within the past 3 months, and no alcohol use within 3 days prior to scanning.

Sponsors & Collaborators

• University of Oxford: lead

Study Sites (2)

Vision and Eye Research Institute

Cambridge, United Kingdom

Location

Wellcome Centre for Integrative Neuroimaging

Oxford, OX3 9DU, United Kingdom

Location

MeSH Terms

Conditions

Charles Bonnet Syndrome; Hallucinations; Vision, Low

Interventions

Neuroimaging

Condition Hierarchy (Ancestors)

Perceptual Disorders; Neurobehavioral Manifestations; Neurologic Manifestations; Nervous System Diseases; Signs and Symptoms; Pathological Conditions, Signs and Symptoms; Vision Disorders; Sensation Disorders; Eye Diseases

Intervention Hierarchy (Ancestors)

Diagnostic Imaging; Diagnostic Techniques and Procedures; Diagnosis; Diagnostic Techniques, Neurological; Investigative Techniques

Study Officials

• Jasleen K Jolly, DPhil

  University of Oxford

  PRINCIPAL INVESTIGATOR

• Betina Ip, DPhil

  University of Oxford

  STUDY CHAIR

• Holly Bridge, DPhil

  University of Oxford

  STUDY DIRECTOR

Study Design

• Study Type: observational
• Observational Model: CASE CONTROL
• Time Perspective: CROSS SECTIONAL
• Sponsor Type: OTHER
• Responsible Party: SPONSOR

Study Record Dates

• First Submitted: February 17, 2021
• First Posted: March 2, 2021
• Study Start: September 1, 2021
• Primary Completion: December 20, 2023
• Study Completion: December 20, 2023
• Last Updated: May 9, 2024

Record last verified: 2024-05

Locations

GB (2)