Rethink Mental Illness is calling on policy makers to ensure the debate around the legalisation of cannabis for recreational purposes reflects the likely impact on the most vulnerable in society and those at greater risk of, or living with, severe mental illness.

Recognising strong arguments for a change in the law, Rethink Mental Illness is calling for a more concerted effort to determine if the overall level of public harm would increase if cannabis were legalised.

The charity argues that without robust research and consultation, including further evidence and education of potential health risks, measures to regulate the potency of cannabis on the market, and a consideration of deterrent pricing policies combined with guards against aggressive marketing tactics, any move to legalise the drug could risk fuelling the nation’s mental health crisis and place a huge financial burden on the system.

A YouGov poll found that five percent of UK adults indicated that they would like to use cannabis regularly (at least once a month or more), rising to nearly 1 in 10 between the ages of 25 and 44 (9%). This would equate to approximately 2.7 million UK adults regularly using cannabis.

However, nearly a fifth (18%) of those polled were unaware of the potential health risks, with 56% identifying that cannabis use is associated with an increased risk of psychosis.

The use of high potency cannabis, or skunk, increases the likelihood of developing psychosis, which can result in hallucinations and delusions long after the effects of the drug have worn off. Psychosis can be a symptom of mental illness, including schizophrenia, schizoaffective and bipolar disorder.

Brian Dow, Deputy CEO of Rethink Mental Illness said:

“We recognise the problems with the current law. Despite cannabis being illegal, it remains one of the most used drugs in the UK. Its potency is increasing, meaning more people are potentially at risk of mental illness.

“In seeking to overcome the current problems of criminalisation, we must guard against inadvertently creating a public health emergency.

“This debate has already been given a lot of airtime, but people are less eager to confront the potential impact of legalisation on some of the most vulnerable people in society. We need to redefine the debate.

“The needs and unique risks to people severely affected by mental illness must be at the heart of any conversation about the future direction of cannabis policy in this country. We need more research, evidence and education before any significant decisions are made.”

Sir Robin Murray, Professor of Psychiatric Research and Chair of the Rethink Mental Illness’ Clinical Advisory Group, said:

"One third of all new patients diagnosed with psychosis in London would not have got ill if they hadn’t used high potency cannabis. So, this is a clear indicator that our current system is not working.

“It is tempting to look at models in other countries for the answers, but for example in the USA, States that have legalised cannabis for recreational purposes have seen an increase in the use and potency of cannabis, and even more cannabis-related problems. Here in the UK we need a very careful review of our laws so that any revision does not make our problems worse”

Simon Gray, who has lived experience of bipolar disorder said:

“The law didn’t influence my choice to use cannabis. I used cannabis in my late 20s and early 30s and I’m in no doubt that it contributed to the deterioration of my mental health. Ultimately, I was sectioned at the age of 35. It was hard to ignore the fact that many of the people in hospital with me also had a history of using cannabis.

“This issue isn’t going to go away. There are reasons why people enjoy using cannabis, but we should educate people more about the potential risks. We need to look at what can be done to help people avoid experiencing a crisis in their mental health, as I did.”

To find out more information about cannabis and mental health, please read our cannabis and mental illness factsheet.

All figures, unless otherwise stated, are from YouGov Plc.  Total sample size was 2082 adults. Fieldwork was undertaken between 13th - 14th January 2020.  The survey was carried out online. The figures have been weighted and are representative of all UK adults (aged 18+). 2.7 million is 5% of the UK’s adult (aged 18+) population (53,128,889)