New study to see whether CBD can reduce psychosis in Parkinson’s

Our research and Parkinson’s teams have teamed up on a groundbreaking trial that aims to find out whether cannabidol (or CBD) is an effective treatment for patients with Parkinson’s disease, who also experience psychosis.

The CANnabidiol for Parkinson’s Disease Psychosis trial (also known as CAN-PDP) is a clinical drug trial open across a number of hospitals in the UK, that’s investigating whether CBD is a safe and tolerable treatment for reducing psychotic symptoms, such as hallucinations and delusions, in patients with Parkinson’s.

About three in five people with Parkinson’s experience symptoms, such as seeing, hearing, or feeling things that are not really there, which are hallucinations, or experience strange beliefs, which are known as delusions. These symptoms are referred to as Parkinson’s disease psychosis (PDP).

The current treatment strategies for this condition are either not very effective, safe, or convenient for everyday use, which is why the trial is looking at CBD as a safer, more tolerable alternative treatment.

CBD is a non-addictive chemical that’s naturally found in the cannabis plant. Research has shown that CBD may safely and effectively reduce psychotic symptoms, but this has not been tested for psychosis specifically in Parkinson’s patients who are taking other medications.

The study team is also conducting a brain imaging sub-study to investigate the brain changes that occur in patients experiencing psychosis during Parkinson’s, and whether CBD reduces these changes.

Nishi Singh, one of our research nurses, says she’s pleased that our trust is able to contribute to such an important study that could have wide ranging implications for this group of patients.

“The CAN-PDP study is aiming to recruit 120 patients across the UK,” she says. “In Somerset, we’ve been set a target of two patients, and we’ve already reached this, although we’re going to keep recruiting until the study closes in August this year.

“I think it’s a really exciting study for our trust to be involved in and it could make a huge difference for patients with Parkinson’s who’re experiencing psychosis.

“We know that not all patients with Parkinson’s have symptoms of psychosis, delusions or hallucinations, but for those who do, it’ll be good to understand whether CBD can have a therapeutic effect in reducing those symptoms.”

Kimberley Gillman, who is another research nurse involved in the trial, adds: “The main centre for the trial is in London, and we are the only NHS trust in the south west taking part, which means patients are visiting us from as far as Devon and Cornwall to take part in the study.

“Patients will be referred to us, or they can self-refer and we will invite them to come and see us in clinic, where we first conduct a few screening tests to make sure that they are eligible before entering into the study.

“Hallucinations can have quite an impact on the patient and those around them. It can be quite unsettling and scary for them when the people that they love are experiencing psychosis.

“If they qualify, then we ask them lots of questions, take some of their bloods, and have a chat to see what their hallucinations are like, and the effect it’s having on the people around them.

“We see them again a couple of weeks later, where we then randomise them into the study, where they’ll either be given CBD capsules or a placebo (which means they just get standard treatment without the CBD) for a period of 12 weeks.

“It has been a great start as we already have two participants in the study – which means that we have achieved our target – however we would be happy to recruit more people into this study.

“I’m finding it exciting to be involved in this trial, as I’ve always found Parkinson’s a fascinating condition, and this could go on to change how treat patients in the future.”

Dr Sarah Cleaver, one of our care of the elderly consultants and our trust's principal investigator for the study, adds: "It's really exciting to be part of a national study looking to improve the quality of life of patients suffering with psychosis alongside their Parkinsons, as our current options for treatment are limited and psychosis can be so debilitating."

Naz Ekizoglu, a clinical research associate at King’s College London, which leads on the CAN-PDP study, adds: “We’re truly excited about the potential of CBD to change how we support people with Parkinson’s who experience hallucinations and delusions.

“It’s been great to have Somerset as one of our study sites, their team has been incredibly collaborative and a pleasure to work with. We are genuinely grateful for their dedication and the hard work they’ve put into making this research possible!”