Gregor Russell1, Alistair Burns2. 1. Daisy Hill House,Lynfield Mount Hospital,Bradford BD9 6DP,UK. 2. University of Manchester and Manchester Academic Health Science Centre,Oxford Road,Manchester M13 9PL,UK.
Abstract
ABSTRACT Background: Charles Bonnet syndrome (CBS) is defined as complex persistent visual hallucinations in the absence of mental disorder. It is common in conditions causing significant visual impairment. Many authors advise reassurance, considering the condition benign. However, others have suggested that CBS may in some patients represent the early stages of dementia. This review seeks to systematically examine the evidence for any link between CBS and cognitive impairment. Methods: Literature search using OVID Medline, PsychINFO, and Embase. Results: Three studies where cognitive functioning was the primary focus of the research were found. All were small, did not properly apply diagnostic criteria, and reported conflicting results. Eight other studies commented on cognitive functioning, but none used tests sufficiently sensitive to detect changes seen in early dementia. One hundred and thirty four case reports were scrutinized, and reports found of 16 patients with CBS where dementia emerged. High rates of partial insight at diagnosis of CBS were seen in these patients. Conclusions: There have been no adequately powered studies, using accepted diagnostic criteria, where changes in cognitive functioning were the primary outcome. Existing studies are of limited methodological quality and allow no conclusion regarding a relationship between cognitive impairment and CBS to be reached. Numerous case reports of dementia developing in patients with CBS and partial insight raise the possibility of a link between these conditions. There is a clear need for properly constructed studies to investigate this.
ABSTRACT Background: Charles Bonnet syndrome (CBS) is defined as complex persistent visual hallucinations in the absence of mental disorder. It is common in conditions causing significant visual impairment. Many authors advise reassurance, considering the condition benign. However, others have suggested that CBS may in some patients represent the early stages of dementia. This review seeks to systematically examine the evidence for any link between CBS and cognitive impairment. Methods: Literature search using OVID Medline, PsychINFO, and Embase. Results: Three studies where cognitive functioning was the primary focus of the research were found. All were small, did not properly apply diagnostic criteria, and reported conflicting results. Eight other studies commented on cognitive functioning, but none used tests sufficiently sensitive to detect changes seen in early dementia. One hundred and thirty four case reports were scrutinized, and reports found of 16 patients with CBS where dementia emerged. High rates of partial insight at diagnosis of CBS were seen in these patients. Conclusions: There have been no adequately powered studies, using accepted diagnostic criteria, where changes in cognitive functioning were the primary outcome. Existing studies are of limited methodological quality and allow no conclusion regarding a relationship between cognitive impairment and CBS to be reached. Numerous case reports of dementia developing in patients with CBS and partial insight raise the possibility of a link between these conditions. There is a clear need for properly constructed studies to investigate this.
Authors: John O'Brien; John Paul Taylor; Clive Ballard; Roger A Barker; Clare Bradley; Alistair Burns; Daniel Collerton; Sonali Dave; Rob Dudley; Paul Francis; Andrea Gibbons; Kate Harris; Vanessa Lawrence; Iracema Leroi; Ian McKeith; Michel Michaelides; Chaitali Naik; Claire O'Callaghan; Kirsty Olsen; Marco Onofrj; Rebecca Pinto; Gregor Russell; Peter Swann; Alan Thomas; Prabitha Urwyler; Rimona Sharon Weil; Dominic Ffytche Journal: J Neurol Neurosurg Psychiatry Date: 2020-03-25 Impact factor: 10.154