Medical cannabis prescriptions have been on the rise in the UK since a 2018 law change allowed specialist registered doctors to prescribe to patients with a variety of conditions. To access medical cannabis, patients must have previously trialled at least two alternative licensed therapies for their condition. Most prescriptions for unlicensed cannabis-based medical products (CBMPs) are written in specialist private clinics, with NHS decision-makers citing a lack of studies demonstrating cost-effectiveness.
In 2019, Sapphire Medical Clinics launched the UK Medical Cannabis Registry to collect prospective, clinical data on patients prescribed CBMPs. A recent study aimed to analyse the health-related quality of life (HRQoL) and safety outcomes for participants in the registry who were treated for symptoms associated with attention-deficit/hyperactivity disorder (ADHD).
What is ADHD?
ADHD is one of the most common psychiatric disorders, with an estimated global prevalence of 5% in children and 2.5% in adults. Symptoms including inattentiveness, trouble with concentration, hyperactivity, and impulsiveness characterise the condition. ADHD is also often associated with psychosocial difficulties, such as relationship problems, unemployment, and educational underachievement. Furthermore, people with ADHD also report a higher incidence of comorbidities, including sleep problems, anxiety, depression, and substance misuse.
Current treatments for ADHD may include psychological therapies alongside both stimulant and non-stimulant medications. While medications have been found to be useful in managing some symptoms of ADHD, medication adherence rates are relatively low, highlighting the need for novel therapeutics for ADHD.
ADHD and Medical Cannabis
The endocannabinoid system (ECS) is a receptor system that has been found to play a vital role in several physiological and cognitive functions. Dysregulation in the ECS has been implicated in the pathophysiology of ADHD. This may make cannabinoid receptors (CB1 and CB2) a potential target for future novel ADHD therapeutics.
To date, only one randomised controlled trial (RCT) has assessed CBMPs in the treatment of ADHD. As such there is a need to generate further evidence to assess the outcomes in individuals with ADHD who are prescribed these medications.
Design and Methods of the Study
Patient data was extracted from the UK Medical Cannabis Registry on 9th January 2023. The UK Medical Cannabis Registry records demographic data and medical history, indications for CBMP prescription, CBMP formulation, route of administration, doses, and comorbidities. Extracted data also included cannabis and smoking history and information about concurrent ADHD treatment medications. Changes to information about the patient’s medications between follow-up appointments and the incidence of adverse events were also reported.
Patient-reported outcome measures (PROMs) were recorded at baseline and 1, 3, 6, and 12 months. PROMs were recorded using the generalised anxiety disorder-7 (GAD-7), single-item sleep quality scale (SQS), and EQ-5D-5L.
Outcomes from the UK Medical Cannabis Registry
A total of 68 patients with ADHD were included in the final analysis, of which 61 (89.71%), 53 (77.94%), 50 (73.53%), and 33 (48.53%) completed PROMs and 1, 3, 6, and 12 months, respectively. The majority of patients were male (n = 55; 80.88%) and were cannabis users (n = 55; 80.88%) at the point of enrolment in the UK Medical Cannabis Registry.
Patient-Reported Outcome Measures
There were changes in anxiety severity and sleep quality scores between baseline and across all follow-up periods at 1, 3, 6, and 12 months. Clinically significant changes in GAD-7 scores were observed in 50% of patients at 1 month, 42.65% (n = 29) at 3 months, 39.71% (n = 27) at 6 months and 26.47% (n = 18) at 12 months.
There were also changes in general health-related quality of life, as assessed by the EQ-5D-5L Index Value, at 1, 3, and 6 months, but not at 12 months, compared to baseline.
Eleven (16.18%) patients reported a total of 61 adverse events, with the most common severity class being moderate (n = 26; 38.24%). The most reported adverse events were insomnia (n = 5, 7.35%), concentration impairment (n = 5, 7.35%), somnolence (n = 5, 7.35%), lethargy (n = 5, 7.35%), and dry mouth (n = 5, 7.35%). No incidences of life-threatening or disabling adverse events were reported.
Conclusions
This study is the first to assess clinical outcomes of patients from the UK Medical Cannabis Registry with a primary diagnosis of ADHD who were prescribed CBMPs for up to 12 months. It is also one of the first studies to investigate the adverse events of CBMPs in individuals with ADHD. These findings show that treatment with CBMPs was associated with changes in general HRQoL after 1, 3, and 6 months, in addition to anxiety and sleep quality across all follow-up periods.
However, the authors of this study do note some limitations in the study design. For example, while these results are promising, a causal relationship cannot be determined. Nonetheless, these findings guide further investigation to assess the therapeutic efficacy and long-term safety profile of CBMPs.
Finally, the authors conclude with recommendations that “comparative analysis should be performed on patients in the UK Medical Cannabis Registry for future evaluations, and importantly, it is essential to conduct high-quality RCTs for the treatment of ADHD whilst controlling for potential confounding factors.”
