First-Ever Clinical Trial To Assess CBD As Treatment For Psychosis In Parkinson’s

Study will determine, for the first time, if CBD can correct the abnormal functioning of the brain that’s causing symptoms such as hallucinations and delusions.

King’s College London, one of the top 25 universities in the world, is teaming up with Parkinson’s UK for a £1.2-million clinical trial to determine the safety and efficacy of CBD in treating Parkinson’s-related psychosis, characterized by hallucinations and delusions.

“We will be assessing how safe CBD is for people with Parkinson’s, what the correct dosage is and how it is tolerated alongside the different medications someone with the condition may already be on,” said lead researcher Dr. Sagnik Bhattacharya, professor of Translational Neuroscience and Psychiatry at King’s College London

The announcement comes ahead of final guidance on medicinal cannabis which is due to be published by The National Institute for Health and Care Excellence next month.

“Unfortunately the drug which was added to my regime to treat dyskinesia gave me hallucinations.”

Paula Scurfield (71), from Beckenham, London, was diagnosed with Parkinson’s in 2014 after developing a very slight tremor on one side of her body.

To treat the symptoms of slowness of movement, stiffness and rigidity in muscles and fatigue, she was given the drug Levodopa. As a result she developed dyskinesia which is a common side effect.

To treat the side effect, she took the drug Amantadine which caused hallucinations at the periphery of her vision.

A lot of trial and error

Current treatments for psychosis typically work by blocking dopamine receptors which can increase the problems people with Parkinson’s experience with movement and other symptoms of the condition.

Scurfield said it took a lot of trial and error to get a combination of medication that helped with her symptoms. 

“Unfortunately the drug which was added to my regime to treat dyskinesia gave me hallucinations – I would see animals running past me in the periphery of my vision every day,” said Scurfield.

“At the beginning I thought I was imagining it but then I realised it was a phenomenon.

“I knew it wasn’t real but it was the most bizarre feeling and I felt a bit scared. My doctor cut the dose in half, which stopped the hallucinations for now.”

Paving the way for a regulated cannabinoid-based medicine

In the UK, there are no medications licenced for Parkinson’s-related psychosis.

Parkinson’s UK director of research Dr. Arthur Roach said the clinical trial could pave the way for a regulated cannabinoid-based medicine “as opposed to self-administration of expensive supplements that have not been monitored for their composition or effects.”

Bhattacharya hopes the study will progress to large-scale clinical trials in what would be “the final step towards becoming a new treatment that will improve the lives of people with Parkinson’s,” he said.

To find the optimum dose, CBD will be delivered orally in capsules at a dose of up to 1,000 mg/day.

In the second stage, 120 people with Parkinson’s-related psychosis will be recruited to take part in a 12-week double-blind, placebo-controlled study. 

The study is expected to start recruitment early next year. It will begin with a six-week pilot.

The three-and-a-half-year project is part of the Parkinson’s Virtual Biotech, led by Parkinson’s UK, which provides funding and fast-tracks projects with the greatest scientific potential, to transform the lives of people with Parkinson’s.

Interest in using cannabis for symptom relief

In a recent survey by Parkinson’s UK, people with Parkinson’s said they would continue to use, or start using, cannabis-derived products if robust evidence became available that they are safe and effective in treating Parkinson’s symptoms.

Survey sheds light on the experience with cannabis among people with Parkinson’s

Between January and March 2019, Parkinson’s UK asked 1,600 people with Parkinson’s and 29 health and care professionals to tell them about their experiences with, and opinions on, using cannabis-based products.

The key findings were as follows:

59% hadn’t used cannabis-derived products before, but would consider using them to control their symptoms

26% had used cannabis-derived products (16% are currently using them for their Parkinson’s and 10% have used them in the past)

16% hadn’t used cannabis-derived products and aren’t interested in using them in the future

Overwhelmingly, people with Parkinson’s would continue to use, or start using, cannabis-derived products if robust evidence became available that they’re safe and effective in treating Parkinson’s symptoms.

To read the full cannabis and Parkinson’s survey findings, visit

About Parkinson’s

Parkinson’s is what happens when the brain cells that make dopamine start to die. There are over 40 symptoms, from tremor and pain to anxiety.

There are currently 145,000 people living with Parkinson’s in the UK and between 50 and 60 per cent of them will be affected by psychosis at some point in their life.

Hallucinations occur when individuals see, hear or feel things that are not really there. Delusions involve developing fixed beliefs that are not true.

These symptoms can be frightening and distressing for people with Parkinson’s and their families and are typically managed with the removal of medication used to treat Parkinson’s.

If the symptoms persist, antipsychotic drugs are sometimes used, however this can result in worsened motor symptoms and side effects.

About King’s College London

Kings College London is one of the top 25 universities in the world (2017/18 QS World University Rankings) and among the oldest in England. King’s has more than 26,500 students (of whom nearly 10,400 are graduate students) from some 150 countries worldwide, and nearly 6,900 staff. The university is in the second phase of a £1 billion redevelopment programme which is transforming its estate.

The Institute of Psychiatry, Psychology & Neuroscience (IoPPN) at King’s College London is the premier centre for mental health and related neurosciences research in Europe. It produces more highly cited publications in psychiatry and mental health than any other university in the world (Scopus, 2016), with 21 of the most highly cited scientists in this field. World-leading research from the IoPPN has made, and continues to make, an impact on how we understand, prevent and treat mental illness and other conditions that affect the brain.