Charles Bonnet syndrome and cognitive impairment: a systematic review

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.

Charles Bonnet syndrome: a literature review into diagnostic criteria, treatment and implications for nursing practice

Charles Bonnet syndrome is a disease of vision which may be mistakenly identified as manifestations of psychosis and consequently be treated by psychiatrists and mental health nurses rather than ophthalmologists. This literature review considers current understanding of the syndrome, its treatment and the role of mental health nurses. The two main findings of the review are that despite a long recognition of the syndrome, diagnostic criteria are not established and that there is no recognized evidence-based medical treatment. As well as this, two novel treatments which may offer future benefits are discussed. Current best practice is identified as identifying the condition and providing reassurance and education, a role that mental health nurses that are aware of Charles Bonnet syndrome can fulfil perhaps better than any other discipline.