A major study is being launched to see if people with psychosis or psychotic symptoms can benefit from cannabidiol (CBD).
CBD is the second most abundant active ingredient in cannabis but does not give a high by itself and there is no evidence people can become addicted.
The NHS only prescribes it for a few conditions such as severe epilepsy, people with certain multiple sclerosis symptoms, and those with vomiting and nausea caused by chemotherapy.
However, it’s also thought it could help reduce anxiety and insomnia.
A £16.5m grant from the Wellcome Trust to the University of Oxford’s psychiatry department will now be used to start a global study involving 1,000 people.
Some of those taking part will be at high risk of psychosis, others will be patients who’ve already had a first psychotic episode or those with psychosis who haven’t responded to other treatments.
Thirty-five centres will be involved, mainly in Europe and North America, and the CBD is being supplied free by a pharmaceutical company.
Professor Philip McGuire, who will lead the research, said CBD was “one of the most promising new treatments” for psychosis patients.
“Many people with psychosis are open to trying cannabidiol and previous smaller-scale studies have indicated that it has beneficial effects,” he said.
“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.”
The cannabidiol being used in the study is Epidyolex, a liquid that is already approved for some children and adults with epilepsy.
Lynsey Bilsland, from the Wellcome Trust, said it was important to try new therapies because traditional antipsychotic drugs can sometimes have “significant side effects” and don’t work for everyone.
She said researchers would also try to identify “biomarkers – biological signposts – which would indicate that a patient might respond well”.
Health stores in the UK can also legally sell CBD products such as oils, capsules and skincare.
However, the NHS says they tend to contain very small amounts so there is no guarantee of their quality or potential benefits.
