Objective: To establish whether frontal cognitive deficits associated with visual hallucinations in Parkinson’s disease (PD) are also present in patients with Charles Bonnet Syndrome (CBS).

Background: Visual hallucinations in PD are associated with more rapid cognitive decline and increased risk of moving into care from independent living. These poorer outcomes may be a consequence of frontal dysfunction, with evidence in previous studies of deficits in verbal fluency, response inhibition (Go/NoGo) and Stroop interference in patients susceptible to visual hallucinations. Whether such deficits predispose to visual hallucinations in all clinical contexts remains unclear. The NIHR-funded SHAPED programme (Study of HAllucinations in Parkinson’s disease, Eye disease and Dementia) is exploring visual hallucination risk factors, outcome and management across different conditions. Well-defined cohorts of patients with PD, with and without visual hallucinations and stratified by level of cognitive impairment, are being recruited to compare with eye disease, Alzheimer’s disease, Dementia with Lewy Bodies and vascular dementia cohorts.

Methods: SHAPED uses the same battery of tests for all participant groups to allow direct comparison of scores, including a version of the MMSE adapted for use in visual impairment, a Go/NoGo task using auditory instructions, FAS verbal fluency and an imagery task. Preliminary analysis of the SHAPED eye-disease cohort has been undertaken to determine whether baseline frontal executive function differs between patients with and without a history of hallucinations.

Results: The first 108 patients with eye disease were included in the analysis, 74 with a history of visual hallucinations (CBS) and 34 without visual hallucinations. There was no difference in MMSE score, Stroop interference, verbal fluency, imagery or Go/NoGo performance between the two groups (all p values > 0.1).

Conclusions: Unlike visual hallucinators with PD, patients with a history of CBS do not have prominent frontal executive deficits suggesting the underlying mechanism of hallucinations in PD and eye disease differs. The observation questions the usefulness of hallucination treatment strategies for eye disease in PD, and vice versa, and raises the possibility that PD visual hallucinators with co-incident eye pathology have a different cognitive trajectory to those in whom vision is intact.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/visual-hallucinations-and-executive-dysfunction-in-charles-bonnet-syndrome-preliminary-findings-from-shaped/