Negative outcome Charles Bonnet Syndrome

Background 
Charles Bonnet Syndrome (CBS) is widely considered a transient condition without adverse consequence, questioning the need for treatment. Yet, while this view may be true of the majority of people with CBS, it is recognised that some have negative experiences and outcomes. Here, we attempt to better understand negative outcome CBS and the factors that influence it.

Methods 
4000 members of the Macular Society were sent a structured questionnaire covering the phenomenology of CBS, its prognosis and impact, symptom reporting, patient knowledge and sources of information.

Results 
492 people with CBS were identified. Kaplan-Meier analysis suggested 75% had CBS for 5 years or more. Thirty-two per cent had negative outcome. Factors associated with negative outcome were: (1) frequent, fear-inducing, longer-lasting hallucination episodes, (2) one or more daily activities affected, (3) attribution of hallucinations to serious mental illness, (4) not knowing about CBS at the onset of symptoms. Duration of CBS or the type of content hallucinated were not associated with negative outcome.

Conclusions 
CBS is of longer duration than previously suspected with clinically relevant consequences in a third of those affected. Interventions that reduce the frequency, duration or fear of individual hallucination episodes and education prior to hallucination onset may help reduce negative outcome.