Medical Cannabis Treatment in Autism: A Systematic Review

There has been a dramatic increase in the number of children diagnosed with autism spectrum disorders (ASD) worldwide, and with that, anecdotal evidence of possible therapeutic effects of cannabis products has emerged as well. The aim of this article is to characterize the epidemiology of ASD patients receiving medical cannabis treatment and to describe its safety and efficacy.


There has been a 3-fold increase during the last three decades in the number of children diagnosed with autism spectrum disorders worldwide. No specific treatments are currently available, and interventions are focussing on lessening the disruptive behaviors, training, and teaching self-help skills for a greater independence. Recently, CBD enriched cannabis has been shown to be beneficial for children with autism.

  • In a retrospective study on 60 children, behavioural outbreaks were improved in 61% of patients, communication problems in 47%, anxiety in 39%, stress in 33% and disruptive behaviour in 33% of the patients.

The rationale for this treatment is based on the previous observations and theory that cannabidiol effects might include alleviation of psychosis, anxiety, facilitation of REM sleep and suppressing seizure activity. A prospective single-case-study of Dronabinol (a THC-based drug) showed significant improvements in hyperactivity, lethargy, irritability, stereotypy, and inappropriate speech at 6-month follow-up. After seeing the results of cannabis treatment on symptoms like anxiety, aggression, panic, tantrums, and self-injurious behaviour, in children with epilepsy, parents of severely autistic children turned to medical cannabis for relief.

Although many with autism are being treated today with medical cannabis, there is a significant lack of knowledge regarding the safety profile and the specific symptoms that are most likely to improve under cannabis treatment. Therefore, the aim of this article is to characterize the patient population receiving medical cannabis treatment for autism and to evaluate the safety and efficacy of this therapy.


During the study period, 188 ASD patients initiated the treatment; at baseline parents of 188 patients reported on average of 6.3 ± 3.2 symptoms – the prevalence of symptoms with most common being restlessness (90.4%), rage attacks (79.8%) and agitation (78.7%).

            1 Month Follow-Up

After one month, out of 188 patients, 8 (4.2%) stopped treatment, 1 (0.5%) switched to a different cannabis supplier, and 179 patients (94.6%) continued active treatment. Of the latter group, 119 (66.4%) responded to the questionnaire with 58 patients (48.7%) reporting significant improvement and 37 (31.1%) moderate improvement.

6 Month Follow-Up

After six months, of the 179 patients assessed in the one-month follow-up, 15 patients (8.3%) stopped treatment, 9 (4.9%) switched to a different cannabis supplier and 155 patients (86.6%) continued treatment. Of the latter group, 93 (60.0%) responded to the questionnaire with 28 patients (30.1%) reporting a significant improvement, 50 patients (53.7%) moderate improvement, 6 patients (6.4%) slight improvement.

Quality of Life Index

Quality of life, mood, and ability to perform activities of daily living were assessed before the treatment and at six months. Good quality of life was reported by 31.3% of patients prior to treatment initiation while at 6 months good quality of life was reported by 66.8%. Positive mood was reported by the parents on 42% before treatment and 63.5% after 6 months of treatment (p < 0.001). The ability to dress and shower independently was significantly improved from 26.4% reported no difficulty in these activities prior to the treatment to 42.9% at six months. Similarly, good sleep and good concentration were reported by 3.3% and 0.0% (respectively) before the treatment and on 24.7% and 14.0% during an active treatment.

The improved symptoms at 6 months included seizures, of the 13 patients on an active treatment at six months 11 patients (84.6%) reported disappearances of the symptoms and two patients reported improvement; restlessness and rage attacks were improved in 72 patients (91.0%) and 66 (90.3%) respectively.


Cannabis as a treatment for autism spectrum disorders patients appears to be a well-tolerated, safe and seemingly effective option to relieve symptoms, mainly: seizures, tics, depression, restlessness and rage attacks. Overall, more than 80% of the parents reported significant or moderate improvement in the child’s global assessment.

The exact mechanism of the cannabis effects in patients with ASD is not fully elucidated. Findings from ASD animal models indicate a possible dysregulation of the endocannabinoid (EC) system signalling behaviours, a dysregulation that was suggested to be also present in ASD patients. Mechanism of action for the effect of cannabis on ASD may possibly involve GABA and glutamate transmission regulation.

  • ASD is characterized by an excitation and inhibition imbalance of GABAergic and glutamatergic signalling in different brain structures. The EC system is involved in modulating imbalanced GABAergic and glutamatergic transmission.
  • Other mechanisms of action can be through oxytocin and vasopressin, neurotransmitters that act as important modulators of social behaviours. Administration of oxytocin to patients with ASD has been shown to facilitate processing of social information, improve emotional recognition, strengthen social interactions, reduce repetitive behaviours and increase eye gaze. Cannabidiol was found to enhance oxytocin and vasopressin release during activities involving social interaction.

Two main active ingredients (THC and CBD) can have different psychoactive action mechanisms. THC was previously shown to improve symptoms characteristic to ASD patients in other treated populations. For example, patients reported lower frequency of anxiety, distress and depression, following THC administration, as well as improved mood and better quality of life in general. In patients suffering from anxiety, THC led to improved anxiety levels compared to placebo and in dementia patients, it led to reduction in nocturnal motor activity, violence behavioural and severity of behavioural disorders. Moreover, cannabis was shown to enhance interpersonal communication and decrease hostile feelings within small social groups.

It has been shown that a CBD enriched treatment of ASD patients can potentially lead to an improvement of behavioural symptoms. These findings are consistent with the findings of two double-blind, placebo-controlled crossover studies demonstrating the anxiolytics properties of CBD in patients with anxiety disorder. In one, CBD had a significant effect on increased brain activity in the right posterior cingulate cortex, which is thought to be involved in the processing of emotional information, and in the other, a simulated public speaking test was evaluated in 24 patients with social anxiety disorder. The CBD treated group had significantly lower anxiety scores than the placebo group during simulated speech, indicating reduction in anxiety, cognitive impairment, and discomfort factors.

The cannabis treatment appears to be safe and side effects reported by the patients and parents were moderate and relatively easy to cope with. The most prevalent side effects reported at six months was restlessness, appearing in less than 6.6% of patients. Moreover, the compliance with the treatment was high and only less than 5% have stopped the treatment due to the side effects. We believe that the careful titration schedule especially in the ASD paediatric population is important for maintaining a low side effects rate and increase of the success rate.

While this study suggests that cannabis treatment is safe and can improve ASD symptoms and improve ASD patient’s quality of life, we believe that double blind placebo-controlled trials are crucial for a better understanding of the cannabis effect on ASD patients.

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