The $300 a week medicine Daniel feels better without

There is no evidence medicinal cannabis is effective for treating anxiety, depression and PTSD, a new study has found, despite hundreds of thousands of Australians being prescribed the products to treat mental health conditions.

Prescriptions for medicinal cannabis products have ballooned from less than 20,000 scripts in 2020 to almost 1 million last financial year.

Psychiatric and mental health conditions are among the most common reasons given for prescribing legal cannabis in Australia.

Since it was legalised for medicinal use in Australia in 2016, more than 250,000 people with anxiety, 19,000 with post-traumatic stress disorder and 17,641 with depression have been prescribed products through the federal government’s Special Access Scheme.

But in a large-scale systematic review, published in Lancet Psychiatry on Tuesday, researchers from the University of Sydney found no evidence that medicinal cannabis was an effective treatment for any of these three conditions.

There was no benefit for treating anorexia. There was some evidence that cannabis could help reduce tic severity for people with Tourette’s syndrome, increase sleep time for insomniacs and help manage autism traits, but the quality of studies included in the review was low.

Dr Jack Wilson, lead author and researcher at the University of Sydney’s Matilda Centre, said that while medicinal cannabis had been legal in some US states for decades, there had been very few randomised control trials – the gold standard for medical research – assessing its safety and effectiveness.

“A lot of people find their cannabis to be effective for their condition, and that is great,” Wilson said. “But when we look at the evidence as a whole, it’s just really not there yet to justify the routine use of these medicines for mental health disorders.”

Iain McGregor, professor of psychopharmacology and director at the Lambert Initiative for Cannabinoid Therapeutics, which is also based at the University of Sydney, agreed more high-quality research was needed into cannabis therapies.

But McGregor said the analysis should not be taken as conclusive evidence due to the age and low quality of the studies included.

Another weakness, McGregor said, was that the research did not distinguish between products containing tetrahydrocannabinol (THC), the primary intoxicating compound found in the cannabis plant, and cannabidiol-dominant cannabis (CBD), which is non-intoxicating.

“The danger of taking a review like this to set policy is that you confuse an absence of evidence with a conclusion that we shouldn’t prescribe because cannabis doesn’t work,” he said.

Legal cannabis sales have tripled in Australia in four years, but research has not kept pace with prescribing rates, McGregor said.

He said cannabis companies had little incentive to invest in randomised clinical trials, which can cost anywhere between $3 million and $10 million, “when there is an exponential increase in prescribing anyway”.

A spokesperson for the Cannabis Council, which represents medicinal cannabis producers, prescribers and pharmacists, said the peak body supported high-quality research. But it did not respond directly to questions about the industry’s funding of clinical trials.

They pointed to submissions to the Therapeutic Goods Administration’s regulatory review from patients describing the benefits they had experienced.

In Australia, several clinical trials are under way to test medicinal cannabis for mental health conditions. These include three studies involving children with autism, and a study led by the mental health centre Orygen testing whether CBD can reduce symptoms of anxiety in young people who have not responded to conventional treatment.

Daniel Yacoel, 33, was prescribed medicinal cannabis two years ago to help him deal with anxiety and depression following a relationship breakdown.

While he had smoked marijuana recreationally in the past, he found himself growing more reliant on the legal product, which was more potent in psychoactive THC.

“Any time I wasn’t at work, I’d be using it,” Yacoel, who lives in Darwin, said. “In the back of my mind, I knew it was an addiction.”

At the peak, Yacoel was consuming 60 grams of cannabis a month, and he was spending more on scripts than his $300 weekly rent. The cost, and the realisation he was slipping into dependency, led him to quit.

“When I initially started using it, I thought that it was doing wonders for my mental health and my anxiety,” he said. “In hindsight … I think it was probably a bit more detrimental.”

In the four months Yacoel has been off cannabis, he has found his mental health has improved, his emotions are more regulated and he is getting better quality sleep.

“I’m still doing the same things I was doing when I was using it, just everything seems a bit easier,” he said. “It’s probably one of the best decisions I’ve made.”

National Alcohol and Other Drug hotline 1800 250 015. Family Drug Support Australia 24/7 Support Line – 1300 368 186

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