A Canadian survey has found evidence to suggest that medical cannabis is associated with sustained improvements in anxiety and depression.

In what is thought to be the largest dataset of its kind, Canadian researchers surveyed over 7,000 patients authorised to access medical cannabis products.

According to their findings, published in the journal Psychiatry Research, patients with symptoms of anxiety and/or depression report sustained improvements following the use of cannabis.

Authors reported “statistically significant improvements” between subjects’ baseline and follow up scores on validated measurements of anxiety and depression. 

Greater improvements were seen in patients who were actively seeking medical cannabis to treat these particular conditions. 

Furthermore, according to the study, the symptom improvements seen were sustained for at least one year.

Building the evidence

The survey is thought to be the largest to date, exploring the effects of medicinal cannabis on anxiety and depression.

Findings from the UK also indicate that patients are finding it helpful for symptoms of these conditions.

The UK Patient Registry, which now includes data from around 2,000 patients, showed statistically significant improvements in anxiety, pain and sleep quality scores following treatment with medical cannabis.

Meanwhile data from the observational study, Project Twenty21, shows cannabis may be more effective at improving mood during the first three months of treatment, than some commonly prescribed antidepressants.

The authors concluded: “To our knowledge, this study is the largest completed to date examining the impact of medical cannabis use on anxiety and depression outcomes utilising longitudinal data and validated questionnaires.

“It provides evidence on the effectiveness of medical cannabis as a treatment for anxiety and depression that otherwise is not currently available, demonstrating that patients who seek treatment with medical cannabis for anxiety and depression can experience clinically significant improvements.”

They added: “This study offers reasonable justification for the completion of large clinical trials to further the understanding of medical cannabis as a treatment for anxiety and depression.”

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New data from Australia, shows cannabis has been prescribed over 140 conditions since 2016, with anxiety among the most common.

The first in-depth study of Australia’s medicinal cannabis programme, shows the treatment has been prescribed for over 140 different conditions since it began in 2016. 

In total, 248,000 prescriptions have been approved for Australians since the inception of the scheme. 

Researchers at the University of Sydney’s Lambert Initiative for Cannabinoid Therapeutics, analysed data from the Therapeutic Goods Association’s (TGA) medical cannabis dataset  – Australia’s Special Access Scheme B – which is the only one of its kind in the world. 

No other country has monitored prescriptions in this way since launching their own medical cannabis programmes.

The study found anxiety was among the top three reasons for patients being prescribed cannabis, the other two being pain and sleep disorders.

This reflects similar patterns in the UK, where chronic pain and anxiety are the most frequently prescribed for conditions, according to data from Project Twenty21. 

The team also found that the number of medicinal cannabis prescriptions have increased significantly since 2020 – over 85 percent of total prescriptions to date have been given since January 2020. They are currently unable to say whether the rise was pandemic related.

Lack of clinical evidence 

However, the researchers have warned that there is a limited number of high-quality clinical trials investigating the drug’s efficacy for these conditions.

Senior author Dr Elizabeth Cairns said the current evidence base for medicinal cannabis for anxiety is limited to only a few studies investigating CBD-dominant products, rather than THC-containing products

“Historically, the effects of THC have been described as anxiety-inducing, although this may depend on dose size and other factors.”

The evidence of effectiveness for medicinal cannabis in the treatment of pain is controversial, at least in Australia, where the Australian Faculty of Pain Medicine suggests not to prescribe medicinal cannabis for this purpose. Very few studies have also been done examining cannabis for the treatment of sleep disorders.

Study co-author and medicinal cannabis prescriber in her capacity as a GP, Associate Professor Vicki Kotsirilos AM from Western Sydney University, says the top reasons for prescriptions didn’t surprise her.

“Pain, anxiety and sleep issues are often interconnected – chronic pain can also cause mental health and sleep issues,” she says. 

Associate Professor Kotsirilos, who prescribes medical cannabis for pain, says this should only be done as a last resort, after more evidence based behavioural and drug therapies, such as counselling, exercise and deep breathing for pain, anxiety and/or sleep disorders, have failed or are of limited clinical benefit. 

Other interesting findings

The size of the dataset allowed the researchers to find prescribing patterns in small, but significant, populations that otherwise might have been overlooked.

“Apart from the link between anxiety and flower products, we found other interesting associations, for example, prescriptions of topical CBD for convulsions,” Dr Cairns said.

“This usage has not been extensively explored.”

The authors note, however, that the data doesn’t include patient outcomes.

Dr Cairns said: “Unfortunately, we just don’t know if these treatments were effective for these patients, but this data highlights where we can focus our attention next – to do focused studies and/or clinical trials.”

“There is a clear, unmet need for effective drug treatments across a variety of conditions that may be being helped with medicinal cannabis. For example, it could be worth conducting high-quality clinical trials on the use of flower products for anxiety, and that is certainly something that the Lambert Initiative and its collaborators may look to do in future.”

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My quality of life has improved significantly since starting to use medical cannabis, writes Justin Clarke, who is neurodivergent, in that he is autistic and has ADHD.

I consider both my being autistic and ADHD to be linked – this is because both significantly impact my sensory processing. I consider them to be ways to describe differences in the way my mind works to the perceived norm. 

I suffer in terms of mental health from anxiety and depression and I am working through complex trauma in therapy. I attribute many of my mental health struggles to the challenges of living as a neurodivergent person in a world that is frequently invalidating and rarely tries to understand or accommodate without a fight.

I’m now 33, and was officially diagnosed as autistic during my last semester at university at the age of 22, and as being ADHD (Combined Type) just two years ago.

Autism is a lifelong neurodevelopmental difference, which affects how people communicate and interact, as well as emotional and sensory processing – amongst many other things. 

Autism tends to be described as being like a spectrum and it can affect people in many different ways. I view it as a spectrum of varying colours and shades, with a lot of complexity to it, rather than as a straight line that goes from ‘mild’ to ‘severe’. Things aren’t that simple at all.

Functioning labels such as ‘high functioning’ and ‘low functioning’ are losing favour in recent times, as we begin to recognise and accept that one’s level of “functioning” is not static and can vary significantly from day to day depending on how it is defined and by whom.

I describe the sensory overwhelm I often experience as being like having all of my senses with the sliders turned up on a figurative stereo equaliser, with no ability to turn them down. 

Cannabis makes them easier to control and process.

Meanwhile, ADHD is a neurodivergence that can involve impulsive behaviours and unusual levels of hyperactivity as well as difficulties with motivation and attention span. 

As with autism it is usually diagnosed in childhood and the way it affects people can vary significantly. There are commonly described to be three types; ‘Inattentive’, and ‘Impulsive’, and ‘Combined’.

Justin Clarke, 33.

Discovering cannabis

I was first prescribed medical cannabis for anxiety following the establishment of Project Twenty21 by Drug Science in 2020. 

Anxiety has been a frequent visitor and presenter of challenges to me as a neurodivergent person living in a world designed for the fabled ‘default human’ or neurotypical. 

Sensory and social anxiety are the main forms of anxiety that I find cannabis to be helpful for – the way it helps with these mainly is by allowing me to better filter and modulate my senses.

I am more socially relaxed and can better participate in conversation when I am not experiencing sensory overwhelm. I don’t get overloaded so quickly by lots of sensory info of different kinds coming in at once.

I can better ‘tune in’ to sensory experiences such as eating food and listening to music. I can enjoy these things without cannabis but it helps me to better immerse myself in them and the experience.

With my sensory processing figuratively eased by cannabis, I also find that executive functioning-related challenges such as staying focused and motivated on tasks to become more achievable.

Social situations

My quality of life has improved significantly since starting to use medical cannabis.

Another thing I find cannabis helpful for is social situations and being around people like in crowded places such as music gigs. This again is mainly because of how it enables me to better tolerate sensory discomfort and anxiety. With it’s help I am able to feel more relaxed in crowds and in unfamiliar social situations.

I am also working through some emotional trauma in therapy and have found cannabis to be helpful in enabling me to talk more openly, as well alleviating some of the trauma-related anxiety that has sometimes resulted from my sessions.

A gentler medication 

From 2014 to 2018, I was prescribed sertraline, an antidepressant that belongs to a group of drugs called selective serotonin reuptake inhibitors. I would describe it as having been very emotionally numbing most of the time, although it was helpful in some ways.

Using cannabis for my anxiety and depression has enabled far better quality of life compared with sertraline in hindsight. It has especially been helpful in topically alleviating anhedonia – the loss of the ability to enjoy things.

I’ve also taken prescribed amphetamines to cope with ADHD which have been useful at times depending on the situation, but they kill my appetite and disturb my sleep, so I tend to use cannabis alongside them to calm down and stimulate my appetite.

Both help my concentration and motivation in different ways, however cannabis is far gentler.

Amphetamines are like an on switch, whereas cannabis gives me the freedom to choose to tune in to what I’m doing and often tends to induce a state of calm inquisitiveness in me.

More often than not, I’ve been able to entirely replace my use of amphetamines with medical cannabis. Unfortunately with it only available privately it is significantly more expensive which means replacing the NHS-prescribed stimulants with them entirely isn’t yet really an option.

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