Visual hallucinations can be distressing for people with Parkinson’s or Dementia with Lewy bodies. Treatment usually involves reducing Parkinson’s medications or offering medications called cholinesterase inhibitors e.g., Donepezil or Rivastigmine. If the hallucinations still cause distress, an antipsychotic medication can be used; however, these have side effects or burdensome monitoring requirements.
The TOP HAT study aims to find out whether ondansetron, a drug already used in the NHS as an anti-sickness treatment, will be both effective and well tolerated as a treatment for visual hallucinations in people with Parkinson’s or Lewy Body Dementia.
The study is recruiting participants with bothersome hallucinations and randomly assigning them to either a treatment group or a placebo group. The treatment group will receive ondansetron in the form of a pill, while the placebo group will receive an identical pill that that does not contain ondansetron.
Participants will attend at least three in-person appointments; a first appointment, with further appointments 6 and 12 weeks after this. Assessments of symptoms will be carried out during treatment (after 6 and 12 weeks), and once treatment ends (18, 24 weeks), to measure hallucinations, delusions (false beliefs), Parkinson's symptoms, memory, quality of life, possible side-effects such as constipation and headache, and the proportion of people who drop out due to side effects, or require additional treatment for their hallucinations.
Study locations
This study is managed by the Neuroprogressive and Dementia Network of NHS Research Scotland.
University College London is the lead recruitment site for the ondansetron trial, you can find out more by visiting the TOP HAT page on the UCL website (external website).
