Understanding medical cannabis and ADHD

ADHD: an overview 

Attention Deficit Hyperactivity Disorder (ADHD) is a neurodivergent disorder, which affects someone’s behaviour. People with ADHD often show a persistent pattern of inattention and/or hyperactivity–impulsivity that interferes with their day-to-day functioning and/or development.

ADHD affects everyone in different ways, but the most common examples are that an individual may seem restless and/or impulsive and have difficulty concentrating.

It is usually diagnosed in childhood before the age of 12 and may be noticed when a child's circumstances change, such as when they start school. But in some cases it may be diagnosed later in childhood or even in adulthood, if the symptoms were not recognised earlier.

It is still not known what causes ADHD. According to the NHS, some research has identified  possible differences in the brains of those with the condition, when compared with those without. Although it can occur in anyone, it is more common in people with learning difficulties.

Other factors which the NHS says have been suggested as potentially having a role in ADHD include:

• Premature birth
• Low birthweight
• Smoking, drinking alcohol or using drugs during pregnancy

What are the symptoms of ADHD?

The symptoms of ADHD can vary from person to person, but according to the NHS, they can be broadly categorised into two different types of behavioural problems:

• Inattentiveness - or difficulty concentrating and focusing
• hyperactivity and impulsiveness

Some people have symptoms which fall into both these categories, but around 3 in 10 people with the condition have problems with inattentiveness but not with hyperactivity or impulsiveness. This form of ADHD is also known as attention deficit disorder (ADD).

It’s also important to be aware that the symptoms of ADHD present differently in males and females, and those present in children and teenagers may be different to the symptoms an adult experiences. 

Some of the typical symptoms of inattentiveness in children and teenagers include:

• having a short attention span and being easily distracted
• making careless mistakes – for example, in schoolwork
• appearing forgetful or losing things
• being unable to stick to tasks that are tedious or time-consuming
• appearing to be unable to listen to or carry out instructions
• constantly changing activity or task
• having difficulty organising tasks

While the main symptoms of hyperactivity and impulsiveness include:

• being unable to sit still, especially in calm or quiet surroundings
• constantly fidgeting
• being unable to concentrate on tasks
• excessive physical movement
• excessive talking
• being unable to wait their turn
• acting without thinking
• interrupting conversations
• little or no sense of danger

Symptoms are harder to define in adults as they tend to be more subtle, but a list of possible symptoms associated with ADHD listed on the NHS website includes:

• carelessness and lack of attention to detail
• continually starting new tasks before finishing old ones
• poor organisational skills
• inability to focus or prioritise
• continually losing or misplacing things
• Forgetfulness
• restlessness and edginess
• difficulty keeping quiet, and speaking out of turn
• blurting out responses and often interrupting others
• mood swings, irritability and a quick temper
• inability to deal with stress
• extreme impatience
• taking risks in activities, often with little or no regard for personal safety or the safety of others – for example, driving dangerously

Related conditions in ADHD 

Children and teenagers with ADHD are also more prone to related conditions and comorbidities, these include:

• anxiety disorder
• depression
• sleep problems
• autistic spectrum disorder (ASD)
• dyspraxia 
• epilepsy 
• Tourette's syndrome 
• learning difficulties, such as dyslexia

Adults with ADHD may also be more likely to experience related conditions such as:

• Personality disorders
• Obsessive compulsive disorder 
• Bipolar disorder 

How common is ADHD?

Around 2.6 million people in the UK are now thought to have a diagnosis of ADHD. According to NICE, it affects 5% of children and 3-4% of adults.

In recent years there has been an increase in people being diagnosed with ADHD in adulthood, which could be linked to an increased awareness of neurodivergent conditions. According to a study from University College London in 2023, there has been a 20-fold increase in ADHD diagnoses over the last two decades, and a 50-fold increase in ADHD prescriptions in men aged 18-29.

What are the current treatments for ADHD?

There is no cure for ADHD, but sometimes treatment can help the symptoms become more manageable and ensure they have less of an impact on an individuals’ daily life. Treatment is usually in the form of therapy and medication, and often a combination of both.

There are currently five medications licensed for the treatment of ADHD in the UK, the most common of which is methylphenidate. Like methylphenidate, most of the drugs prescribed for ADHD are known as stimulants but you may also be prescribed a selective noradrenaline reuptake inhibitor (SNRI), which increases levels of the chemical noradrenaline in the brain and is thought to improve concentration and control impulses. 

All of these medications come with varying side-effects and are more effective for some people than others. 

Meanwhile talking therapies, such as cognitive behavioural therapy (CBT), behaviour therapy and psychoeducation may help someone in managing their symptoms. 

Eating a healthy, balanced diet and taking supplements such as the fatty acids omega-3 and omega-6 fatty acids may be beneficial for people with ADHD, although the evidence is limited. 

Medical cannabis and ADHD

Is medical cannabis prescribed for ADHD?

Yes. In the UK ADHD is actually one of the most common conditions for which medical cannabis is prescribed. 

Around a third of patients enrolled on Drug Science’s patient registry, T21, have an anxiety disorder as their primary condition, while another 10% have other diagnosed psychiatric conditions, the second most common being post-traumatic stress disorder (PTSD), followed by depression and ADHD. 

Data published by T21 in 2022 also showed that secondary anxiety disorders are more common in patients with ADHD (68.3%) than the rest of the sample which had a primary condition other than an anxiety condition (40.6%).

What does the research say on the use of medical cannabis in ADHD?

Despite the prevalence of its use, there is still limited scientific evidence for the safety and efficacy of medical cannabis in the treatment of ADHD.

To date, there has only been one placebo-controlled randomised controlled trial (RCT) examining this. In 2015, a small pilot study investigated the cannabinoid-based medication, Sativex, in 30 adults with ADHD. Researchers found preliminary evidence ‘supporting the self-medication’ of cannabis use in ADHD and recommended further studies on the endocannabinoid system in this specific condition.

Elsewhere, a systematic review of existing studies looking at cannabis and ADHD, found 13 papers reporting improvements in symptoms including concentration, motivation, learning, memory, and impulsivity. 

In a separate review of papers published over the last 10 years, researchers attempted to understand the nature of the relationship between cannabis use and symptoms of ADHD. According to the authors, the findings shed new light on the perceived effects of cannabis on specific symptoms and the potential moderating effects of cannabis on executive functioning deficits related to ADHD, which has been “‘largely ignored” by previous research. 

However, they say: “The evidence to date is inconclusive regarding whether cannabis use has an addictive effect or interactions, whether beneficial or detrimental. The evidence base at this time is relatively small, so more study is needed.”

What do patients say about medical cannabis and how it helps them?

While the clinical evidence may be limited, there is a wealth of real-world data from patients who report significant benefit from medical cannabis on their symptoms and quality of life. 

A study using data from the UK Medical Cannabis Registry suggests that patients prescribed cannabis-based medicinal products for ADHD showed improvements in sleep, anxiety and overall quality of life. 

Researchers also noted a reduction in use of other ADHD medications among the patient group. Prescription of lisdexamfetamine was reduced by 38% during the study, methylphenidate by 15% and dexamfetamine by 14% – all of which can cause negative side-effects, according to the authors.

Researchers at Washington State University conducted an online survey involving 1,738 students with ADHD. Participants who had used cannabis reported that it has “beneficial effects” on many symptoms of ADHD, including hyperactivity and impulsivity. Cannabis was also said to improve most of their medication side effects, such as irritability and anxiety.

Separately, a case report examined three male patients, between the ages of 17-23, who were using medical cannabis to help manage their symptoms. According to the paper, the improvements in all three participant’s symptoms and quality of life were “substantial”, with all three finding they were “more able to keep their emotions in check”, and two were able to take on a new job with more responsibility.

All three patients who took part in the study experienced “positive improvements” on measures for depression, emotional regulation, and inattention.

What are the best cannabis strains for ADHD?

As it stands, research on medical cannabis is not advanced enough to be able to determine with any certainty which strains are best suited to which health conditions. However, looking at the terpenes which are present in a particular strain and reading up on their potential benefits may give you some indication. For example, if you struggle with focus and concentration, you may wish to explore strains which are reported to help with these. 

How can I get a medical prescription for ADHD?

If you have a diagnosis of ADHD and think you may benefit from treatment with medical cannabis, it’s important to do so under the guidance of a medical professional. 

You can use the Releaf eligibility checker to determine if it's right for you. A team of expert clinicians will then review your application and if appropriate you will be invited to schedule an appointment with a specialist consultant.

During the initial consultation you will have the opportunity to discuss your symptoms and needs with the consultant and if they feel it’s appropriate they will issue your prescription and guide you through the next steps. 

You can find out more about medical cannabis via the FAQs page or by contacting a member of the team.