Studies have shown that a number of adults diagnosed with Attention-Deficit/Hyperactivity Disorder (ADHD) describe self-medicating with cannabis products, either in addition or in preference to traditional ADHD medications. Although a small number of psychiatrists in the USA have been known to prescribe medical cannabis in some cases, this is not routine in many of the jurisdictions which currently have developed medical cannabis frameworks. However, there remains anecdotal evidence that has prompted more research in the area.
What is Attention-Deficit/Hyperactivity Disorder?
ADHD is one of the most common neurodevelopment disorders, with the majority of cases being diagnosed during childhood. It is thought to affect around 5% of children and 3% of adults. Although the causes of ADHD are not completely understood, it is widely believed that both genetics and environmental factors can play a part in its development.
The disorder is characterised by a number of symptoms which often lead to decreased attention and increased distraction and impulsive behaviour. Children diagnosed with ADHD often struggle to focus during education and may face social difficulties with family and friends. Common signs of ADHD include fidgeting, lack of concentration, and restlessness.
Current Treatments for ADHD
Treatment options for ADHD include a variety of cognitive behavioural therapies, psychological therapies and medications. In the treatment of ADHD in children, therapy options tend to be favoured, whereas the use of medications such as stimulants and noradrenaline reuptake inhibitors may be more common in teens, young adults, and adults.
Assessing the Potential of Cannabinoids in Treating Symptoms of ADHD
Despite growing anecdotal claims for the use of cannabis-based medicinal products in ADHD treatment, in addition to the recommendation of a number of clinicians in the USA, there remains a paucity of evidence to support its use. However, a 2017 study published in European Neuropsychopharmacology set out to further understand this potential through their randomised placebo-controlled trial.
Over a six-week period, a total of 30 participants were given a dose of Sativex – a preparation of cannabinoids which contains a 1:1 ratio of cannabidiol (CBD) and tetrahydrocannabinol (THC) – or placebo. To accurately record the outcomes of the treatment course, participants wilfully ceased existing treatment with stimulants and/or psychoactive drugs for one week prior to, and during the study.
Cognitive performance and activity level (head movements) were measured using the Quantitative Behavioural Test (Qb Test) after dosing of each treatment. These results were compared with the baseline results (prior to the start of either treatment) throughout the duration of the study.
Throughout the study period, a small number of participants, in both the active and placebo groups, experienced adverse events. One participant of the active (Sativex) treatment group withdrew from the trial following the onset of muscular spasms/seizures. This was treated as a serious adverse event, though the reaction has not been reported in previous Sativex studies.
Three more participants of the active group experienced mild adverse side effects during treatment. These side effects included light-headedness and diarrhoea and resolved within a few days allowing for continuation with the trial. A final participant in the placebo group experienced an increased heart rate, the cause of which was not identified.
This trial showed that the active groups treated with the medical cannabis product Sativex experienced a nominally significant improvement in hyperactivity/impulsivity, cognitive measure of inhibition, as well as a trend towards an improvement in inattention and emotional lability. However, no significant difference in cognitive performance and activity levels was found between groups according to the Qb score. The findings from this study suggest that adults with ADHD may represent a subgroup of patients for whom cannabinoids may provide a reduction in symptoms without cognitive impairments.
The researchers suggest that, although this is not a definitive study, the findings may support the medication of ADHD with medicinal cannabis, whilst highlighting the need for further studies in the form of randomised controlled trials and real-world evidence collection.