UK-based study to test effectiveness of CBD on psychosis

Oxford University in the UK has received a multi-million pound grant to explore whether CBD is effective in treating symptoms of psychosis. 

The global study will involve three clinical trials, led by researchers at Oxford University, to investigate the effectiveness of cannabidiol (CBD) in treating people with psychosis or psychotic symptoms.

Wellcome has awarded Oxford’s Department of Psychiatry £16.5 million for the STEP (Stratification & Treatment in Early Psychosis) programme, as part of its support for mental health research.

The programme, led by Professor Philip McGuire, Professor of Psychiatry at Oxford, will involve 1,000 participants, including people at a clinically high risk for psychosis, people with first episode psychosis, and people with psychosis who have not responded to conventional treatment.

The study which is due to get underway later this year will use the CBD-based drug Epidyolex, which is reportedly being supplied by Jazz Pharmaceuticals (formerly GW Pharma) at no cost.

Epidyolex is an isolated form of CBD which is prescribed on the NHS for seizures in rare forms of epilepsy including Dravet syndrome and Lennox-Gestaut syndrome.

Professor McGuire said: “Cannabidiol is one of the most promising new treatments for people with psychosis. This study will be the first to evaluate cannabidiol in large numbers of people with psychosis or psychotic symptoms, and brings together many of the leading centres working in this area around the world.

“Many people with psychosis are open to trying cannabidiol and previous smaller scale studies have indicated that it has beneficial effects. As well as treating psychosis that is already established, the study will also investigate whether cannabidiol can prevent the onset of psychosis in people at high risk of developing it. 

“This study could provide us with a new kind of treatment for psychosis and we are hugely grateful to Wellcome and Jazz Pharmaceuticals for helping to make it happen.”

CBD as a potential treatment for psychosis

A number of previous studies have begun to explore the potential of CBD as a treatment for psychosis. A study from 2021 found that CBD-cigarettes had an ‘antipsychotic medication sparing effect’, when used as an adjunctive treatment for acute psychosis.

Elsewhere researchers investigating the antipsychotic potential of CBD found that its effects on levels of glutamate (one of the most abundant neurotransmitters in the brain) in the prefrontal cortex were related to ‘lower symptom severity’. The prefrontal cortex is the part of the brain responsible for cognitive and social behaviour, personality expression and decision making.

In this new study, participants will be assessed before and after treatment using a range of clinical, digital, cognitive, neuroimaging and blood measures to clarify how CBD acts to produce its effects and to identify factors that predict the response to treatment.

In order to correctly measure the effect of CBD, half of the participants will be treated with placebo and the other half will receive CBD. Either CBD or a placebo will be administered alongside the standard medical treatments for psychosis.

A potential ‘breakthrough’ trial?

Wellcome is a charitable foundation which provides funding for new research into health and wellbeing. According to its website since 2005 it has provided grants for a number of studies globally into the effects of cannabis use, including previous randomised control trials investigating CBD as a treatment for psychosis.  

Lynsey Bilsland, head of Mental Health Translation at Wellcome, said: “This exciting programme will help us to find out if cannabidiol is effective at treating psychosis at various stages by testing it at scale.  

“While antipsychotics are commonly used to treat psychosis, they can have significant side effects, patients often stop taking them, and they don’t work for everyone. This means that it is important that we explore avenues such as this one for new therapies. 

“In addition, as part of these trials the researchers are aiming to identify biomarkers – biological signposts – which would indicate that a patient might respond well to the treatment. This will allow for greater personalisation of treatment in the future.” 

The programme involves 35 centres, mainly in Europe and North America, and will be coordinated from Oxford at the Prince of Wales International Centre for SANE Research, which was opened by King Charles III 20 years ago .

Marjorie Wallace CBE, founder and chief executive of mental health charity SANE, added: “We built the Centre as a flagship of hope for researchers, patients and their families to discover new and more effective treatments and to disseminate information and research into severe mental illness. We are delighted to work with Professor McGuire’s team in this exciting and potentially breakthrough trial.”

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