Parkinson’s psychosis and CBD: ask the expert

Some people with Parkinson’s may experience symptoms such as hallucinations or delusions — this can also be known as Parkinson’s psychosis. But what exactly is Parkinson’s psychosis, and could a chemical in cannabis be the answer to tackling this troublesome symptom?

Quick summary if you’re in a rush:

• Parkinson’s-related psychosis is used to describe psychosis symptoms in Parkinson’s.
• It is currently unclear what causes Parkinson’s psychosis and none of the existing treatments are ideal due to their side effects.
• Research suggests that cannabidiol (CBD), a component of cannabis, might be involved in reducing psychosis but no controlled clinical trial has investigated CBD in people with Parkinson’s.
• Researchers at King’s College London are partnering with Parkinson’s UK through the Parkinson’s Virtual Biotech to carry out a clinical trial to investigate the impact of CBD on Parkinson’s psychosis.

There are many different symptoms of Parkinson’s and not everyone will experience the same ones. Evidence indicates up to 60% of people with Parkinson’s go on to develop symptoms of Parkinson’s psychosis as their condition progresses. And this risk increases in people with Parkinson’s dementia.

These symptoms can be extremely distressing for both the person with Parkinson’s and their families.

We’re joined by Dr Sagnik Bhattacharyya, Dr Latha Velayudhan and Dr Dominic ffytche from King’s College London, they are experts in neurological conditions and psychosis. They will answer some of the key questions on this topic.

What is Parkinson’s psychosis?

Dominic:
Parkinson’s psychosis is a specific term used to describe psychosis symptoms in Parkinson’s and is separate to psychosis found in other conditions. Everyone is unique and not everyone who has Parkinson’s will develop these symptoms. Further to this, people will experience these symptoms in different ways.

Parkinson’s psychosis usually starts with perceptual disturbances where things are misinterpreted, for instance —

• seeing a branch of a tree as a cat
• seeing movements or figures in the corner of your eye
• having a feeling that someone is close or nearby, feeling a presence.

As Parkinson’s progresses psychosis symptoms may evolve into more formed hallucinations, for instance, seeing people or animals that are not there. At this stage people are usually aware when something is a hallucination and can appreciate that it’s not real.

But this can change, and as Parkinson’s progresses, it may be that people can’t separate reality from the hallucinations or delusions. Delusions are strange beliefs. Such as, a belief that —

• things have been stolen
• their spouse is being unfaithful
• someone is out to hurt or harm them.

This stage of Parkinson’s psychosis has more similarities with psychosis found in other conditions, such as schizophrenia.

Why can psychosis occur in Parkinson’s?

Dominic:
Dopamine replacing medication such as Levodopa has been around for over 50 years and it was always assumed that Parkinson's psychosis was a side effect of these medications. Especially as sometimes people report symptoms associated with psychosis after increasing their dose or changing their medication. But this is not always the case, and the fact not everyone experiences psychosis, suggests it must be more than a side effect of the medication.

Now we believe that changes in parts of the brain, including the parts that control movement and vision, may play a role in the causes of Parkinson’s psychosis.

Sagnik:
But overall, we do not fully understand what causes the Parkinson’s psychosis.

Latha:
This symptom can be further complicated if someone develops infection such as urinary tract infection, making them more prone to hallucinations, and this is more common in older people.

What should someone do if they are experiencing psychosis? Are there currently any treatments?

Latha:
In the early stages of Parkinson’s psychosis, when someone is aware that they are experiencing hallucinations or delusions, re-assurance and management strategies such as changing the lighting can help reduce the impact of this symptom.

Once the awareness is lost this might be when people are prescribed medications. One such drug is an anti-psychotic medication called clozapine and although it reduces hallucinations, it has significant side effects and requires having to have regular blood tests and monitoring of cardiac side effects. Another drug called rivastigmine has been shown to reduce visual hallucinations, but this has only been shown in people with Parkinson’s dementia. There is a promising anti-psychotic drug called pimavanserin that is approved in the US but currently not licensed here. However, this medication too has cardiac side effects.

In summary, none of these treatments are ideal.

Dominic:
We also need to think about treatments in a wider sense because carers are often impacted more than the patient with this symptom. Parkinson’s psychosis can be distressing and troubling for the carers and can cause arguments and upset. This is why we are really keen to find a treatment for this symptom.

What research is being done?

Sagnik:
As Latha and Dominic have mentioned, existing treatments for psychosis in Parkinson’s are not very effective and invasive monitoring is not ideal for a long term treatment. We need a treatment that can be simply administered and on a regular basis.

Cannabis has been shown in several studies to increase the risk of developing psychosis. But actually the cannabis plant is made up of many different substances.

Cannabidiol (CBD) is one of these substances and research actually shows that it may potentially have the opposite effect of reducing symptoms of psychosis. There have also been previous studies that have shown that CBD is well tolerated when given as a treatment and seems to have little side effects.

But what has not been done is investigating the impact of CBD on Parkinson’s psychosis. We’re partnering with Parkinson’s UK, through the Parkinson’s Virtual Biotech, to investigate just this. At a cost of £1.2 million over three and a half years, we’re recruiting for a clinical trial to test the safety and benefits of CBD on Parkinson’s psychosis.

The first stage of the trial will recruit up to 24 people with Parkinson’s-related psychosis to an initial six-week study. The focus will be on understanding the safety of CBD in people with Parkinson’s-related psychosis. Participants will be carefully monitored for any side effects or interactions between their current drugs and CBD. A range of doses will be tested to select the most appropriate one to use in the next stage.

In the second stage, we will aim to recruit 120 people with Parkinson’s-related psychosis to take part in a 12-week study. Half the group will receive CBD and half will receive a placebo, a dummy drug. As well as continuing to monitor safety, we will carry out detailed assessments of symptoms associated with psychosis. We will also be keeping an eye on other symptoms.

Finally, 40 participants from the second stage of the trial will be invited to undergo MRI brain scans. We also aim to recruit 20 people with Parkinson’s who do not have psychosis and 20 people of a similar age without either condition to participate in this part of the study. This will enable us to compare patterns of brain activity in the trial participants with those of people who don’t have Parkinson’s related psychosis or Parkinson’s as well as examine the changes in brain activity following treatment. We hope this will help us to understand more about how CBD works.

When recruitment to this study opens we will be advertising this through our Take Part Hub. To receive regular updates about Parkinson’s research, alongside opportunities to take part and get involved, please sign up to join our Research Support Network.

Paula is one of our dedicated research volunteers, she was diagnosed with Parkinson’s in 2014 — she shared her experience with us.

Paula takes Levodopa medication to help manage her movement symptoms and as a result she developed a common side effect of involuntary movements, also known as dyskinesia. It was medication to treat dyskinesia that contributed to her experience of hallucinations.

“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. 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.

“The clinical trial is very exciting and if it provides evidence for the safety and effectiveness of CBD, it could benefit those affected by Parkinson’s-related psychosis.”

CBD — The story so far

The law around cannabis and CBD can be confusing. In November 2018, medicinal cannabis was legalised for certain conditions, but with strict criteria in place, only a handful of people have accessed it to date.

For CBD, as long as sellers don’t make explicit health claims about the product, they don’t need a license to sell it. While this means that CBD is widely available on the high street and online, it also means that there’s
little regulation as to what’s actually in the product you buy.

For Ros, who has Parkinson’s, trying CBD oil to manage her symptoms didn’t work out so well:

“It tasted awful and it only managed to dye my gum shield a funny colour! I’d say more research is needed.”

As more and more clinical trials into CBD happen, we’ll have a better idea of whether it can improve Parkinson’s symptoms. And if it can, proper licensing would guarantee that what’s in each batch of CBD oil is closely regulated.

Huge thanks to Dr Sagnik Bhattacharyya, Dr Latha Velayudhan and Dr Dominic ffytche from King’s College London.

This blog is not meant as health advice. You should always consult a qualified health professional or specialist before making any changes to treatment or lifestyle.

Need to chat to someone?

Our helpline and Parkinson’s local advisers are here to answer any questions you have about the symptoms of Parkinson’s.

Call us on 0808 800 0303 or find out more at www.parkinsons.org.uk/information-and-support/helpline-and-local-advisers