Medical Literature on Charles Bonnet Syndrome

There are over 300 articles on CBS and most of these can be viewed on public library websites. Most of these articles are medical in nature however, and discuss only a single person with CBS. Thus far no medical cure has been found. CBS appears when a person has lost significant vision in one or both eyes from any cause.

Annotated Bibliography on Charles Bonnet Syndrome

This annotated bibliography will be updated from time to time.  The journal articles all deal with Charles Bonnet Syndrome in some way.  When I cannot get access to the article itself, I supply the abstract.

Kelsall-Foreman I, Bucks RS, Weinborn M, Badcock JC. Loneliness and objective social isolation are differentially associated with anomalous perceptions in community-dwelling older adults. Cogn Neuropsychiatry. 2023 Mar;28(2):130-146. doi: 10.1080/13546805.2023.2174841. Epub 2023 Feb 6. PMID: 36744805.

These findings suggest that loneliness and social isolation have differential associations with anomalous perceptions in older adults and provide additional evidence that attending to loneliness in older adults is important.

Robert Bodén, Josefin Nilsson, Ida Walles, Eva Larsson, Ingela Kristiansen, David Fällmar & Jonas Persson (2021) Suppressing visual hallucinations in an adolescent by occipital transcranial magnetic stimulation: A single-case experimental research design, Neuropsychological Rehabilitation, DOI: 10.1080/09602011.2021.2017303

This well-designed single subject study included background MRI scans prior to treatment.  The single subject rated the intensity and distress of CBS experiences at baseline and after treatment.  The subject was blind to whether the treatment was a placebo or actual TMS treatments.  Results were compared within the subject for placebo and actual treatments and to control subjects.  The treatment was purported to reduce cortical excitability.  There were reductions in symptoms for two weeks, and symptoms returned to baseline thereafter.

Congenital Blindness and Psychosis: A Literature Review Retno Tharra Handayani1* Sriwijaya Journal of Ophthalmology (SJO) http://sriwijayaopthalmology.com Vol 5 Issue 1 2021

This literature review presents the evidence that persons with congenital blindness are protected from schizophrenia and highlights the relationship between vision and schizophrenia. Top down versus bottom up processing is explored.  Negative symptoms of schizophrenia are discussed which could potentially aid diagnosis of CBS versus schizophrenia.

Michael J. Firbank, Katrina daSilva Morgan, Daniel Collerton, Greg J. Elder, Jehill Parikh, Kirsty Olsen, Julia Schumacher, Dominic ffytche, John-Paul Taylor, Investigation of structural brain changes in Charles Bonnet Syndrome, NeuroImage: Clinical, Volume 35,2022,103041,ISSN 2213-1582,

 (My comment: Any research on persons with a visual impairment is hampered by low number of subjects, and heterogeneity of subjects.  I think these researchers did an excellent job anyway.)

"Our data suggests that structural alterations may predispose to visual hallucinations, but the primary mechanism in CBS is likely to be alterations in functional connectivity or cortical excitability as the vision system adapts to reduced input and concomitant cortical changes."

 This suggests that there are brain changes as a result of blindness.  A blind brain starts behaving differently from a sighted one in as little as six months from my observations.  Amir Amedi, an Israeli neurologist when asked once replied that that the changes begin in as little as a few hours.

Connections between parts of the brain are always changing in any brain, and it could be that these changes bring on the hallucinations.  This would possibly explain the speed or lack thereof in the onset of CBS.   

Rosenberg, Richard S. PhD; Gupta, Kishan MD, PhD Text on the Walls, Journal of Neuro-Ophthalmology: December 16, 2021 - Volume - Issue - doi: 10.1097/WNO.0000000000001432

This single subject research was on a 67 year old cataract patient who used screen magnification and high contrast colors to use a PC for his work as a psychology lecturer.  Prior to surgery he would see text on walls and ceilings but could only identify individual letters rather than whole words, even though they were often seen as a paragraph.  The connection between cortical areas involving text perception and CBS is discussed.

Caamaño-Ponte, J.; Gómez Digón, M.; Pereira Pía, M.; de la Iglesia Cabezudo, A.; Echevarría Canoura, M.; Facal, D. A Case Study on Polypharmacy and Depression in a 75-Year-Old Woman with Visual Deficits and Charles Bonnet Syndrome. Geriatrics 2022, 7, 5. https://doi.org/10.3390/ geriatrics7010005

This is a case study of a 75 year old woman living in the community who has depression and Charles Bonnet Syndrome.  It discusses the use of antidepressants and the importance of family caregiving. Non-pharmacological treatments are also discussed.

Teunisse, R., Cruysberg, J., Verbeek, A., & Zitman, F. (1995). The Charles Bonnet Syndrome: A Large Prospective Study in the Netherlands: A Study of the Prevalence of the Charles Bonnet Syndrome and Associated Factors in 500 Patients Attending the University Department of Ophthalmology at Nijmegen. British Journal of Psychiatry, 166(2), 254-257. doi:10.1192/bjp.166.2.254

The prevalence of CBS in low-vision patients was 11%. CBS was significantly associated with an age over 64 years and a visual acuity in the best eye of 0.3 or less. No significant associations with ophthalmic diagnoses, patient sex, marital status, or social circumstances were found.

O’Hare, Fleur, Bentley, Sharon, Wu, Zhichao, Guymer, Robyn, Luu, Chi, &Ayton, Lauren(2015)Charles Bonnet Syndrome in Advanced Retinitis Pigmentosa.

Ophthalmology 122 (9), pp. 1951-1953.

 This study is an examination of CBS in persons with retinitis pigmentosa (RP).  It offers some techniques that may be useful and an estimate of the prevalence of CBS in persons with RP. An excellent quote from the article is: “Careful screening, education and reassurance would be beneficial in reducing the unnecessary negative impact.“

Jesse Breedlove; Logan Dowdle; Cheryl Olman; Tom Jhou. (2021)Neural correlates of spontaneous non-optic vision in a blind individual Journal of Vision September 2021, Vol.21, 2848. doi:https://doi.org/10.1167/jov.21.9.2848

 This single subject study looks at a person’s ability to visualize real objects that she has certain awareness of, even though blind.  This does not appear to be CBS, yet the appearance of the objects in a non-optic is involuntary.  Scans show activation of visual centers as if the person were seeing the objects optically.

Shankar, V.V. (2021). Dementia Care Book Chapter Dementia in Under 65s—An Overview. pp 381-395.

The author makes an excellent point saying: “There are often non-cognitive symptoms such as apathy, personality changes and resistant depression that precede the cognitive symptoms of dementia leading to delayed diagnosis.”  Persons with CBS and no dementia, would not have these symptoms.

Jorrit Jan Walinga Geesteswetenschappen, Utrecht University

 This paper appears to be a German dissertation on essentialism.  CBS is only mentioned but the quote below is an interesting way to think of Charles Bonnet

 Examples like visual illusions, and altered states like deliriums, Charles Bonnet syndrome and the psychedelic experience also show that at least during those events we observe our mental model of reality, not reality itself (well, that is the easiest explanation if we want to maintain people share a common reality).

 The idea that we only experience what our brains can construct, in its effort to match bottom-up information with top-down predictions, is also the central idea in the widely influential theory of predictive processing.

Crawford, L. (2014). Imagination: a Container for Infinity. Gray Matters: The undergraduate neuroscience journal.3

 The faculty that enables individuals to recognize that imagined events are not real is known as reality-monitoring, and is thought to be a form of source memory, i.e. one’s ability to remember the origin of information. When reality-monitoring malfunctions, serious psychological harm can result. One particularly extreme example of such a loss in reality-monitoring occurs within schizophrenics [12]. Schizophrenic patients have a range of symptoms including the hallucination of voices and people.

 The difference between individuals with disorders like CBS and those with Schizophrenia is that the latter often report expressly interacting with their hallucinations, sometimes in frightful, harmful or threating ways; their inability to reality-monitor results in emotional responses to their hallucinations.

Rahman, T. et al. (2020). Extreme overvalued beliefs. Journal of the Academy of Psychiatry Law. 40(3).

Delusion

A false belief based on incorrect inference about external reality that is firmly held despite what almost everyone else believes and despite what constitutes incontrovertible and obvious proof or evidence to the contrary. The belief is not ordinarily accepted by other members of the person’s culture or subculture (i.e., it is not an article of religious faith) (Ref. 4, p 819).

Extreme Overvalued Belief

A belief that is shared by others in a person’s cultural, religious, or subcultural group. The belief is often relished, amplified,and defended by the possessor of the belief and should be differentiated from a delusion or obsession. The belief grows more dominant over time, more refined, and more resistant to challenge. The individual has an intense emotional commitment to the belief and may carry out violent behavior in its service (Ref. 3, p 2).

 Obsession

Recurrent and persistent thoughts, urges, or images that are experienced, at some time during the disturbance, as intrusive and unwanted and that in most individuals cause marked anxiety or distress. The individual attempts to ignore or suppress such thoughts, urges,