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Outcomes for Generalised Anxiety Disorder from the UK Medical Cannabis Registry

Published: 21/06/2023

Since 2019, the UK Medical Cannabis Registry has collected real-world evidence from patients prescribed medical cannabis products for a range of conditions. In 2018, cannabis was rescheduled in the UK, allowing for its use in the treatment of several indications, including anxiety. There remains a distinct lack of clinical trials in assessing the effects of medical cannabis on anxiety, but real-world evidence exploring the use of medical cannabis in the treatment of anxiety disorders can provide important insights.

In recent years, the UK has seen a significant rise in cases of anxiety disorders and symptoms. According to research by Mental Health UK, over 8 million people experience an anxiety disorder at any one time. Anxiety disorders are often associated with several other physical and mental symptoms, including sleep disturbances, restlessness, and muscle tension.

Common treatment approaches for anxiety disorders include cognitive behavioural therapy and medications such as selective serotonin reuptake inhibitors (SSRIs) and other antidepressants. While treatment with these medications can be effective, they can carry the risk of significant side effects, including nausea, insomnia and appetite and weight loss. Therefore, the identification of alternatives has become an important area of focus.

Medical Cannabis and Anxiety

A growing body of evidence has implicated the endocannabinoid system (ECS) in several important physiological and cognitive functions, including mood and emotional processing. Cannabinoid receptors, such as CB1R and CB2R, are thought to be important in the anxiety response. The common cannabinoid, cannabidiol (CBD), is an allosteric modulator of CB1R and enhances anandamide levels.

While some studies have found that tetrahydrocannabinol (THC) may be associated with acute increases in anxiety, some research suggests that CBD may ameliorate these negative effects. However, these complex interactions are still far from fully understood, making further research – both clinical and observational – of the utmost importance.

Data Collection for the UK Medical Cannabis Registry

The UK Medical Cannabis Registry (UKMCR), which has been managed by Sapphire Medical Clinics since 2019, is the first UK patient registry to collect data regarding CBMP prescription formulations, patient demographics, patient-reported outcome measures (PROMs) and adverse events (AEs). The current analysis assessed outcomes for patients who had received a medical cannabis prescription for Generalised Anxiety Disorder (GAD).

Methods of the Study

The data used in this analysis were collected remotely via patient-reported outcome measures (PROMs) and adverse events questionnaires that were available electronically at baseline, 1-month, 3-month, and 6-month follow-ups. Primary outcomes were changes in PROMs from baseline to 1-, 3-, and 6-month follow-ups and secondary outcomes were the incidence and severity of adverse events.

A total of 302 patients had baseline anxiety assessments and were included in the final analysis; however, there were moderate rates of missing data with 17.5% missing at 1 month, 31.6% at 3 months, and 37.3% at 6 months.

Patient-Reported Outcome Measures (PROMs)

PROMs were measured using the GAD-7, a self-report questionnaire that evaluates seven aspects of generalized anxiety by the number of days they were experienced in the past fortnight. Other PROMs included the EQ-5D-5L, the HRQoL measure recommended by the National Institute for Health and Care Excellence (NICE), and the SQS utilises a numerical rating scale rating from 0 (terrible) to 10 (excellent) to assess sleep quality over the past 7 days. Adverse events were collected at each follow-up interval through self-reporting, routine follow-up with a clinician or direct questioning by the research team.

Results of the Analysis

Patients prescribed cannabis-based medicinal products (CBMPs) demonstrated changes in GAD-7 at all time points across the study period. GAD-7 response rates were 38.2% (95/249) at 1 month, 40.1% (73/180) at 3 months, and 38.3% (36/94) at 6 months. Furthermore, a 4-point change in GAD-7 scores was seen in 58.2% (145/249) of participants at 1 month, 55% (99/180) at 3 months, and 46.3% (41/94) at 6 months.

Changes in sleep and quality of life scores were also seen across all time points. Individually at 6 months, 39% of individuals experience a clinically significant change in their anxiety, 50% in their quality of life and 35% in their sleep score.

Adverse Events

A total of 269 adverse events were reported by 39 participants (12.9%). Eleven of these participants reported at least one adverse effect that was “severe” in intensity; insomnia was the most reported severe adverse effect with six participants rating their insomnia as severe. The most common adverse effects were dry mouth (n=25; 8.3%), fatigue (n=22; 7.3%), insomnia (n=19; 6.3%), somnolence (n=16; 5.3%), lethargy (n=16; 5.3%) and nausea (n=16; 5.3%).

Patients who had no prior experience with cannabis were more likely to experience adverse effects compared with patients who were currently using cannabis. These findings are in line with existing data.


These results suggest that the use of CBMPs was associated with changes in anxiety, sleep and quality of life measures at all time points after prescription. The authors of this analysis highlight the need for placebo-controlled randomised trials to further test the efficacy of medical cannabis in the treatment of GAD.

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