Management of visual hallucinations in dementia and Parkinson's disease

ABSTRACTObjectives: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.

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*).

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.

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.