New trial of anti-sickness pill to combat hallucinations in Parkinson’s
The TOP HAT study will test whether ondansetron — an anti-sickness pill already used in the NHS — can help to reduce visual hallucinations in people with Parkinson’s or Lewy Body Dementia (LBD).
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Quick summary if you’re in a hurry:
- Hallucinations affect many people with Parkinson’s at some point and can be extremely distressing for patients and their families.
- Current treatment options for managing hallucinations in people with Parkinson’s are severely limited.
- A major new trial — the TOP HAT study — will test whether a currently available anti-sickness drug could help relieve visual hallucinations, and it’s recruiting participants now.
Visual hallucinations are when people see things that aren’t there. They are probably more commonly associated with mental health conditions like schizophrenia, but may affect up to 75% of people with Parkinson’s at some point during the condition.
Visual hallucinations may be subtle. We probably all have moments when we think we’ve seen something out of the corner of our eye but when we turn to look realise there’s nothing there…
And that’s how things can start for people with Parkinson’s or Lewy Body Dementia (LBD). But for some, hallucinations can become much more vivid and troublesome.
Susan and Andy live in Dorset with their daughter. Andy was diagnosed with Parkinson’s at 41, he’s now 66 and living with Parkinson’s and dementia. Andy first started having hallucinations about 12 years after he was diagnosed with Parkinson’s.
“For a year, he was smelling smoke and I would be running around to find the source but there was nothing,” explains Susan.
“A few months ago, one early morning, he woke up at 2am and was fully dressed to go outside to see, what he thought, was the milking parlour. I took him outside and he said he could see cows on the farm.
“The hallucinations have definitely become worse since lockdown. His routine has completely changed and that’s affected his symptoms.
“It really is the worst thing to cope with. He sees insects like wasps and mice on the bedroom floor almost everyday, particularly in the evening.
“Andy gets really scared and I’ve tried to explain things to him but it gets so draining. It is really, really important we find a treatment to treat hallucinations in people with Parkinson’s. It can be so distressing for people like Andy and the carer.”
Read more about hallucinations on the Parkinson’s UK website
About the TOP HAT study
Ondansetron is an anti-sickness drug that is already approved and in use in the UK, mainly to help reduce nausea in people undergoing cancer treatment.
Ondansetron affects visual processing in the brain and its potential for treating visual hallucinations in Parkinson’s was first identified in studies in the early 1990s. At the time, the high cost of ondansetron prevented further studies but it is now affordable.
Parkinson’s UK is now funding a large-scale clinical trial to investigate ondansetron in people with Parkinson’s or Lewy Body Dementia (LBD) who experience moderate to severe visual hallucinations. This means experiencing troubling visual hallucinations on at least a weekly basis.
The trial aims to recruit 306 people with Parkinson’s or Lewy Body Dementia (LBD) across England, Scotland and Wales who have visual hallucinations. People who join the study will be randomly allocated into two equal groups — one group will receive ondansetron for 12 weeks, the other group will receive a placebo — a tablet that looks identical but contains no drug. Neither the participants themselves or the researchers will know who is receiving the real drug and who is receiving placebo until the study is over.
All participants will be carefully monitored throughout the study for any side effects or problems, and they will have full assessments of their symptoms (including hallucinations) several times during the study.
The study has been completely redesigned with people affected by Parkinson’s over the past few months to make sure that it is safe and practical for people with the condition to participate during the pandemic. Major changes to the study include reducing the number of in-person assessments, and replacing these wherever possible with telephone calls or videoconferencing. Not only this, the study drug will be couriered directly to participants homes and they will be given thorough instructions on how to take the pills.
Driving forward a new treatment for hallucinations
Research suggests that up to 75% of people with Parkinson’s may experience hallucinations at some point.
In a recent survey conducted by Parkinson’s UK and researchers at the University of Lancaster, 1 in 10 respondents reported that hallucinations had worsened during the COVID-19 pandemic.
There are currently no specific treatments approved in the UK for people with Parkinson’s who experience hallucinations.
Current management for psychotic symptoms includes:
- reducing Parkinson’s medications (which can trigger or worsen psychotic symptoms) — however, this can mean other Parkinson’s symptoms worsen.
- antipsychotic drugs — however, these medications may worsen Parkinson’s symptoms and can have serious risks and side effects.
If this new phase 2 trial provides evidence that ondansetron is safe and effective it could rapidly be made available to people with Parkinson’s or Lewy Body Dementia (LBD) on the NHS without the need for further studies.
Lead Researcher, Suzanne Reeves, Professor of Old Age Psychiatry and Psychopharmacology at UCL says:
“Visual hallucinations pose a particular challenge in Parkinson’s as the very treatments for motor symptoms in Parkinson’s can also trigger and worsen this distressing symptom. Finding treatments for hallucinations that are both effective and safe is an area of great unmet need.
“This trial will enable us to find out if ondansetron is effective and safe as a treatment and if it is, we could see clinicians prescribing an inexpensive drug with fewer side effects to people with Parkinson’s throughout the UK.”
Interested in taking part?
You can find further information about the TOP HAT study on the Parkinson’s UK website, here: www.parkinsons.org.uk/TOPHAT
If you think you are eligible and wish to take part then please contact the study team directly, using the contact details provided, with any further questions or to express your interest in participating.
If this particular study isn’t for you then there are many other projects taking place across the UK and you can browse them all on our Take Part Hub.
