Call for participants for our clinical trial of GDNF

Hi everyone

As you know we are currently supporting a cutting-edge drug trial of a drug called GDNF which has great potential for people with Parkinson’s.

We have already successfully recruited a number of people with Parkinson’s to take part in this ground-breaking trial but we still need more people to come forward – especially those within relatively easy reach of Bristol, where the study is taking place.

Please help us make this trial successful by reading the information below and passing the information on to anyone who may be interested in the study.


  • Aim: To test whether a drug called GDNF has the potential to slow the course of Parkinson's, which is something no current treatment can do.
  • Who do the researchers need? People aged between 35-75 who have had Parkinson’s for at least 5 years. You need to meet a range of specific criteria to be eligible and be able to travel regularly to Bristol.
  • What is involved? This is a clinical trial of a new treatment for Parkinson’s so taking part involves in-depth assessments, complex surgery and regular visits to the research centre in Bristol for treatment and follow-up visits.



This £2million trial is funded by Parkinson's UK, with support from the Cure Parkinson's Trust and in association with the North Bristol NHS Trust.

Because GDNF is a large protein it's quite difficult to get it into the brain. In this trial participants will have surgery to implant a device that can deliver GDNF directly into the right area of the brain.

The researchers are looking for 36 people with Parkinson's, preferably living within easy reach of Bristol, to take part in this 9-month trial.

Who can take part?

As well as being aged between 35-75 and having Parkinson’s for at least 5 years, to be a suitable candidate you must also experience problems with your Parkinson's medication - in particular, 'off' periods, when the medication stops working and symptoms become severe.

People who have previously had Deep Brain Stimulation, experience severe tremor or dyskinesia, or who have dementia or significant mood problems are not suitable to take part in this study.

All reasonable expenses incurred while taking part in the study will be fully reimbursed.

What is involved?

Taking part in this study is a significant commitment as it involves regular visits to Bristol for assessments, surgery, brain scans and treatment.

Interested in taking part?

For further information please read the full details available on our website carefully and watch the videos to get a full understanding of what the study involves:

If you decide you’d be interested in participating in the study and think you may be a suitable candidate please contact the Parkinson’s UK research team directly: [email protected]  or on 0207 963 9326.

Best wishes


The Research Team


I'm going through the screening process right now.

How do any of us truly know how long we've had the condition? Once you know the symptoms, I suspect many know they've had symptoms for several years before official diagnosis by nerurologist?

I have my initial screening this week.  How far into the process are you and how are you finding it?

Pipework and port scheduled for installation this week. How did you get on?

Part of the  screening is to ask when symptoms began and when diagnosed.

Update on what happens in case it helps others.  

Pre op mobility and cognitive assessments off and on meds

Pre op MRI planning scans


MRI to check pipework and test infusion flow

PET scan

Mobility assessment off and on meds

Infusion time - Either GDNF or Placebo every 4 weeks for 9 months

Mobility assessments off then on meds every 8 weeks 

No idea if on the GDNF or Placebo and that's key to the trial

All of the above is explained in the Patient information leaflet available online







What does GDNF do?

Is it intended as a long term replacement for levadopa?

What are the risks involved in the operation and the subsequent maintenance of the catheter?

What are the known risks from taking GDNF?

Hi Leyther

Many thanks for your interest in our GDNF trial. The team in Bristol leading the trial have now found all 36 participants to take part in this stage of the trial and so recruitment has closed.

Details of the trial are still available on our website here The patient information sheet available on this page sets out in details the risk of both the surgery and the drug itself.

We will of course, let our supporters know if any of the current participants drop out of the trial or if in the future there is a larger trial that will require more participants.

In the meantime however there are lots of other opportunities to take part in research. You might be interested to join our network of research supporters. We email the network opportunities to take part in research studies such as the GDNF trial, all the latest research news and research events. It’s a great way to keep up to date with opportunities to get involved in.

You can join the network on our website here –

We keep a list of Parkinson's research projects around the UK which may be looking for participants on our website here

You can browse the list to find studies in your area. We always recommend that people discuss taking part in research studies with their doctor or nurse.

I hope this is helpful but please do let us know if you have any other queries.

All the best,


The Research Team