What is the study about?
The Top Hat study is testing whether ondansetron—a medication already used in the NHS to treat nausea—can be an effective and well-tolerated treatment for visual hallucinations in people with Parkinson’s or Lewy Body Dementia.
Who can take part?
Individuals aged 18 or over who have Parkinson’s or Lewy Body Dementia and experience visual hallucinations (seeing things that aren’t there) at least once a week. These hallucinations must not be caused by an infection and must have continued despite changes to existing medication.
What is involved?
Comparing ondansetron treatment to placebo, a tablet that looks identical but contains no drug, over 12 weeks with telephone follow up for 12 weeks once treatment ends. TOP HAT will recruit people with Parkinson’s Disease or Lewy Body Dementia. Most of the assessments can be carried out face-to-face, via video consultations or telephone. Only 3 face-to-face visits will be needed, to take a blood sample, to carry out an ECG using a hand help device (no leads required), and to assess your Parkinson’s or Lewy Body Dementia symptoms without making physical contact.