Management of visual hallucinations in dementia and Parkinson’s disease

Abstract

Objectives:Visual hallucinations are a common symptom in dementia and Parkinson’s disease and have been associated with greater cognitive and functional decline, but optimal management strategies are unclear. We review the frequency and pathogenesis of visual hallucinations in dementia and Parkinson’s disease and examine the evidence base for their management.Design:We undertook a systematic review of the visual hallucinations in dementia, searching studies published between January 1980 and July 2017 using PubMed with the search terms visual hallucinations AND review AND (dementia OR parkinson*).Results:We found 645 articles and screened them for relevance, finally including 89 papers (11 meta-analyses, 34 randomized controlled trials, six other trials and a number of relevant review articles). Only six of the trials reported visual hallucination outcomes separately from other neuropsychiatric symptoms.Conclusions:Atypical antipsychotics were frequently studied, but with the exception of clozapine in Parkinson’s disease dementia, results were equivocal. There was some evidence that acetylcholinesterase inhibitors may help visual hallucinations. Overall, effect sizes for most treatments were small and there were few studies with long term follow up. Treatments need to be carefully weighed up with the risks and reviewed often, and many patients improved without treatment. There is a lack of data regarding visual hallucinations due to the grouping of psychotic symptoms together in commonly used rating scales. The lack of a specific rating scales, or analyzable items within other scales, for visual hallucinations, limited efficacy of current and small evidence base with short follow up are important areas for future studies to address.

Nosology and Phenomenology of Psychosis in Movement Disorders

“…Systematic reviews revealed that he most common psychotic symptom in idiopathic Parkinson's disease (IPD) is visual hallucination, with an estimated pooled prevalence of 28.2% (±19.1 to 39.5), followed by isolated delusions (mostly paranoid) . DRT‐induced visual hallucinations are more frequent in IPD than in patients with mutations in PD‐related genes (except for PARK‐GBA that shows similar figures) and are also commonly associated with dementia . In IPD, the content of hallucinations is often stereotyped with frequent descriptions of animals .…”

“…Visual hallucinations commonly occur several years after disease onset and are often associated with DRT and dementia . Response to antipsychotic treatment has been only partial …”

“…46 DRTinduced visual hallucinations are more frequent in IPD than in patients with mutations in PD-related genes (except for PARK-GBA that shows similar figures) and are also commonly associated with dementia. 45,47 In IPD, the content of hallucinations is often stereotyped with frequent descriptions of animals. 48 Unlike genetic parkinsonisms, where multimodal hallucinations combined with delusions are the most frequent psychotic features, minor hallucinations, including passage, feeling of presence, or illusions, are one of the most common early psychiatric symptoms in IPD.…”

Effect of biological treatments on psychotic symptoms in lewy body disease: A systematic review and meta‐analysis of randomized controlled trials

“…Swann and O'Brien 61 performed a systematic review of manuscripts reporting management strategies of visual hallucinations in dementia and PD. They included all study designs in their review but did prioritize RCT's or meta‐analyses.…”

What can we learn from fMRI capture of visual hallucinations in Parkinson’s disease?

“…Since these symptoms may be induced by medication (namely, dopamine agonists), dopaminergic pathways were presumably involved, but not only [Fénelon et al, 2000] [Friedman, 2010]. A number of studies have shown the benefit of acetylcholinesterase inhibitors [Burn et al, 2006] [Swann and O'Brien, 2018], suggesting involvement of the cortical cholinergic pathway. Moreover, visual dysfunction is frequent in patients with PD.…”