medical cannabis ADHD attention deficit hyperactivity disorder

Patient Case Studies for the Use of Medical Cannabis for Attention Deficit Hyperactivity Disorder (ADHD)

Attention Deficit Hyperactivity Disorder – widely known as ADHD – is a highly prevalent chronic neurobehavioral disorder present in both children and adults. The disorder has become increasingly diagnosed in recent years as medical professionals continue to learn more about it. It is most commonly identified in childhood years and over half of those affected also having comorbid psychiatric conditions such as sleep, mood, and anxiety disorders, as we all as oppositional defiant disorder. 

Traditional treatments for ADHD include the use of medications such as methylphenidate, lisdexamfetamine, dexamfetamine, atomoxetine, and guanfacine. Patients with ADHD may also engage with cognitive behavioural therapy or social skills training. Increasingly, however, evidence suggests growing interest in the potential of medicinal cannabis in the setting of ADHD. 

Medical Cannabis and ADHD

Growing acceptance of the medical use of cannabis is continuing to conflict with restricted patient access to approved cannabis-based medical products. This has led to an increase in the number of patients seeking to self-medicate with cannabis, despite a current lack of high-quality clinical evidence for its safety and efficacy. This limited evidence base has persisted, despite ongoing legalisation of medical cannabis, partly due to challenges in conducting randomised and placebo-controlled trials with cannabis. 

Nonetheless, patient-reported outcomes and anecdotal evidence suggest there is potential for medical cannabis as an adjunct in the management of ADHD. For example, one study which analysed online comments for relevant information on cannabis for ADHD found that “at least 3 times as many online comments attested for its therapeutic benefits in comparison with harm or lack of efficacy”. Another study – a case report, identified patients from a psychiatry practice who self-medicated with cannabis, in addition to their prescriptions for ADHD medications. A total of three patients were assessed to determine the potential effects of cannabis products as an adjunctive therapy for ADHD. 

Design and Methods of the Study

The three participants identified for inclusion in the report participated in telephone interviews with one of the authors. The interviews were semi-structured to facilitate a discussion about “the patient’s life prior to initiating cannabis, the decision/reasons for starting it, how (if at all) things have changed since initiating cannabis, logistics on consumption and access, and what (if any) concerns they might have about cannabis.”

A cannabis side effect survey was used to identify side effects experienced by the patients in the last week. ADHD symptoms experienced by the patients were measured using self-report rating scales, including the 90-item Swanson Nolan and Pelham (SNAP-IV) scale, the Screen for Child Anxiety Related Emotional Disorders (SCARED) and Patient Health Questionnaire (PHQ-9). The SNAP-IV scale is used to assess inattention, hyperactivity/impulsivity, and oppositional defiant disorder, as well as items representing a general index of childhood problems. 

The researchers also obtained two blood samples from the participants in order to identify plasma concentrations of cannabinoids and relevant metabolites.

Patient Case Studies

‘Patient 1’ was a 23-year-old white male who had been diagnosed with both ADHD and generalised anxiety disorder. He decided to use cannabis after reading about its effectiveness for ADHD online. Having medicated with methylphenidate, pregabalin, fluoxetine, and clonidine, he first tried cannabis in his teens. Having continued to use cannabis periodically, he eventually consulted his physician and received an authorisation for medical cannabis in a CBD:THC 20:1 ratio, twice daily.

Patient one used both cannabidiol oil and cannabis flower. He found the cannabis flower more relaxing than the oils. He describes cannabis as “a really good helping hand” to compliment his other medications and describes how he now feels more open with others, less anxious, and that his emotions are less exaggerated.

‘Patient 2’, a white male who had been medicating with methylphenidate off and on since the third grade, explains how he dislikes using stimulants as he feels they change his personality. At age 17 he was prescribed lithium. Around the same time, he decided to try cannabis oil in a CBD:THC 20:1 ratio after a family member recommended it to him. Since then, he had taken a combination of lithium (300 mg at bedtime) and cannabis (1 mL at bedtime), which, he says, has helped him to feel more relaxed, improve his focus, and feel more “himself”.

Patient 2 is quoted: “I was definitely a lot more jittery and stuff when I was in school…It helped me to focus a lot more, and it helped me ease off my ADHD meds actually.” Since starting cannabis medicinally, he was able to be successfully weaned off his other medications for ADHD – now only taking lithium for depression and cannabis.

Finally, ‘Patient 3’, a 22-year-old male, was diagnosed with ADHD when he was 20 and started self-medicating with cannabis. Having had no previous experience with cannabis use, the opening of dispensaries in Canada and the fact that a family member was considering its use for anxiety prompted him to try it himself. He told the researcher that he feels cannabis works with his other medications ((dextroamphetamine, amantadine, and pregabalin) in improving his concentration and in controlling his “racing thoughts, anxiety, and emotions”.

Patient 3 stated that he prefers products that are higher in THC and lower CBD. At the time of interview, he was consuming cannabis flower with a CBD:THC ratio of 0:18-19 at bedtime. He has also tried edibles and oils but found that they did not improve his sleep.

Patient-Reported Outcomes

According to the patient-reported outcomes via numerous rating scales, all three patients experienced positive improvements on measures for depression, emotional regulation, and inattention. The scores from patients 1 and 2 also indicate an improvement in the SCARED, which measures symptoms of anxiety.

Despite these improvements, all patients also reported mild side effects associated with cannabis use. These included short-term memory problems (experienced by Patient 2), dry mouth and sleepiness (reported by Patient 1 and Patient 3). Patient 1 also reported “occasional experiences of constant desire and more forgetfulness and apathy”, while Patient 3 reported an altered sense of time.


The researchers note that the findings collected in this study are consistent with previous case reports. In one of the reports, published in 2008, patients reported “improvement in performance tests (ART2020 and TAP) in adult males consuming cannabis, suggesting that THC may have atypical effects in patients with ADHD.” The second report, published in 2018, demonstrated patient-reported improvements in symptoms of ADHD in a patient who was taking a high-THC cannabis product. However, there remains limited evidence in this area, prompting the researchers to recommend further research.