Medical marijuana: effects on pediatric patients with autism and the developing brain

Virginia Thornley, M.D., Neurologist, Epileptologist


May 6, 2018


Medical cannabis is being more and more commonly used in medical conditions specifically neurological. The CB1 receptor is found predominantly within the nervous system and in a few other organs on a lesser basis. The CB2 receptor is mainly in the immune system and found in other organs to a lesser extent.

Recent arguments have arisen promoting medical cannabis in children particularly in those with autism and attention deficit hyperactivity disorder.  It has already been well-established in patients with epilepsy. However, the effects on the developing brains of children have not yet been well-documented as it is not yet widely used or studied in the pediatric population. There are many animal models but this does not always correspond to translate into similar human findings.

Effect in autism in animal models and clinical studies

A current topic of debate is not only using THC in pediatric patients but those with autism. Autism is part of the pervasive developmental disorder consisting of social inhibition and isolation including poor eye contact, delayed language skills, aggressive behavior and may be characterized as having stereotypies such as flapping of the arms. Self-injury, eating and sleep disorders may occur. The etiology may be related to genetic, neurobiochemical or environmental and the exact cause is unclear.

In one animal model study, mice with induced Dravet syndrome-like symptoms was noted to improve in autistic-like social interactions with the addition of low dose cannabidiol (2) of 10mg/kg. At low doses, the DS mice interacted more with stranger mice. At higher doses, this was not noted. Dravet syndrome is a type of epileptic syndrome affecting the SCN1A gene causing medically refractory seizures combined with autism.  However, this was an animal model. Scientific studies do not necessarily translate into positive human clinical results.

There was one case report of a six-year-old boy with early autism. Dronabinol  (delta-9-THC) was administered at 3.62mg a day and followed for 6 months. Using the ABC scale (aberrant behavior checklist), the patient improved in terms of stereotypies which were less, lethargy was reduced, hyperactivity improved, and inappropriate speech improved (4).


Endocannabinoid system and mechanisms in relation to autism

There are several lines of thinking regarding the role of the endocannabinoid and autism. It is thought that the endocannabinoid system plays a role in neurological development, but can also be modulated by outside cannabinoids. Another line of thinking is that autism spectrum disorders may be related to disrupted pathways that have been affected by the endocannabinoid pathway (5). In one animal study, it was found that the oxytocin peptide may be responsible for disrupting normal signaling pathways giving rise to autism spectrum disorders. Oxytocin appears to be crucial in mediating social reward which is impaired in autistic patients. Anandamide seems to play a role in the signaling pathways for oxytocin which is responsible for the social reward.   Social reward is aberrant in those with autism and this pathway thought to play a key role in causing its pathogenesis. By increasing anandamide at the CB1 receptor, ASD and social impairment is improved (5).

Effect on a fetus

Tetrahydrocannabinol is lipophilic and crosses the blood-brain barrier. It can get stored in the fatty stores which are likely the reason it may have a long-lasting effect.  Cannabinoids have been found to cross the placenta and affect the fetus. It may result in hyperactivity and impulsivity in babies with cannabinoid exposure in utero.


Effect on early cerebral development

It was found that in adolescents who used cannabis, there is a reduction in the IQ by the age of 38. It was found that cannabinoid receptors influence axonal migrations as well as subcortical projections within the cerebrum. This affects synaptic connections during childhood and adolescence(3).

The adolescent brain is still not fully matured and likely still subject to neuronal plasticity and changes. It may be affected by substances. One study showed that the frontal lobe is vulnerable to cannabis in adolescents who used it heavily and that cannabis use may impact working memory. (1)





During adolescence, when cannabis is initiated it may affect the neuronal circuitry developing in the immature brain. The richest regions in the brain with cannabinoid receptors are the prefrontal cortex, medial temporal lobes, striatum, white matter connections, and cerebellum. When cannabis is introduced during this neurocritically important time of development, these regions can become dysfunctional although some functional studies have shown altered, weakened, strengthened or combination of changes (6).

Some of the most common adverse effects

At high doses in chronic users, it was found to induce anxiety, panic attacks. It can increase blood pressure. However, clinically, it may control seizures


In summary

There is a small body of evidence from a scientific standpoint that cannabis may work to help alleviate autism-like symptoms based on the animal models. There is a not enough evidence from a clinical evidence standpoint in human studies to support its use in pediatric patients, with one case report that it helped with impulsivity, reduced lethargy, and inattention. Randomized placebo-controlled clinical trials are needed.

Research has found that cannabinoids may help oxytocin and disrupted signaling pathways that play a role in social reward which is impaired in autism. At present, there is evidence that cannabis may affect neurocognitive development but these are studies in pregnant mothers who used it heavily recreationally and adolescents who used it heavily. It is unclear if there may be a similar impact when used in the pediatric population at a medical dosage and administration as there are not enough studies to expound on this.




  1. Jager, et al, “Cannabis use and memory brain function in adolescent boys: a cross-sectional multicenter fMRI study,” J. Am. Acad. Child Adolesc. Psychiatry, 2010, Jun., 49(6):561-572.
  2. Kaplan, et al, “Cannabidiol attenuates seizures and social deficits in a mouse model in Dravet syndrome,” Proceedings of the National Academy of Science, 2017, Oct.. 114 (42):11229-11234.
  3. Scott, et al, “Medical marijuana: a review of the science and implications for developmental-behavioral pediatric practice,” J. Dev. Behav. Ped., 2016, Feb., 36 (2):115-123.
  4. Kurz, et al, “Use of dronabinol  (delta-9-THC) in autism: a prospective single-case study with early infantile autistic child,” Cannabinoids, 2010, 5 (4):4-6.
  5. Wei, et al, “Enhancement of anandamide-mediated endocannabinoid signaling corrects autism-related social impairment,” Cannabis Cannabinoid Research, 2016, 1(1):81-89
  6. Kelly, et al, “Distinct effects of childhood ADHD and cannabis use on brain functional architecture in young adults, Neuroimage Clin., 2017, 13:188-200.



44 thoughts on “Medical marijuana: effects on pediatric patients with autism and the developing brain

    • There’s just not enough studies regarding safety in pregnant women on medical doses. It will cross the placenta. Whereas for children on medical doses, effect on the developing brain is unclear


  1. This is still a taboo subject for me. I mean, I understand that it can help and makes life better for some people, and yes I do think that kids and pregnant women should avoid using it. But if this is the only thing that helps that person going through day to day, why not giving it a shot. We should stop being so judgemental and be more supportive.


    • Yes that is true. I agree 100%. There is truth on both sides. There is a lot of misinformation out there. CBD and low dose THC are non-intoxicating and can help with a wide variety of conditions. Unfortunately there is so much stigma within the public and the medical community because people are more familiar with the recreational side and docs are trained to follow studies. Everything has to start somewhere and it’s been used 5000 years effectively medically.


  2. Amber says:

    I don’t know much about this, so I’m glad I read your post. My son has autism, but he’s 16, and I’m not sure if I’d be comfortable with him using this yet.


    • Well, there is some evidence that it works. There is just not enough information on if it is safe for the developing brain for THC anyway at medical dosing, CBD is non-psychoactive and has less side effects overall. The only problem with the studies is that the side effects were studies on those who used it very heavily and recreationally so the ways of taking it and administration is very very different compared to the medical way through a doctor’s care where it is not smoked and not recommended at very high doses. It’s likely being used widely anecdotally because it works and we’ll have more information in the near future regarding safety at medical doses. Thanks for reading!


  3. This article is very timely. I am in the process of writing an article about the the effects of recreational marijuana on the brain. Most of the research that I have found seem to cite negative effects on the amygdala and nucleus accumbens rather than positive results. Very good read.


    • Thanks, research is like anything it depends on what you read, some research will be biased towards good outcomes others will be biased towards bad outcomes. Thank you for reading


  4. This article is very timely. I am in the process of writing an article about the the effects of recreational marijuana on the brain. Most of the research that I have found seem to cite negative effects on the amygdala and nucleus accumbens rather than positive results. Very good read.


  5. this was really interesting. I have a family member with autism. I’ve never considered what marijauna can do to help or not help. I’m a recreational smoker myself and have always been really careful throughout my pregnancies and when i have nursed my children. wish there was more cocnrete research on the effects of using marijauna during pregnancy.


    • Thanks for reading, there is so e information in babies born to mothers who used it recreationally but I have not come across any where it was used at medical dosages. During pregnancy it will cross the placenta to the baby but at medical dosage and administration there is not enough information on the impact on the developing brain. Thanks for reading


  6. This is an excellent evidence-based article on a subject that will continue to be of much debate. There’s always a trade off with any medicinal treatment of a condition. The “approved medicines” Hagee side effects also, so it’s always a matter of the pros outweigh the chins off any treatment. Thanks for putting this great information together.


    • Thank you for reading, yes this is a very controversial topic people feel strongly about on both sides because there are so many beneficial effects but by the same token there is much negative stigma. In children, however, it is always prudent to exercise caution. Thanks for reading


  7. I definitely agree with cannabis usage when used medically, and with caution, as there are benefits. I think it’s important that studies continue to have a better understanding of its effects on the brain/body.


  8. Indeed, using cannabis really requires caution when being used for medical purposes. I understand that it does good to others who need it but it still needs to be taken with precaution.


  9. This is such an interesting topic and more research clearly needs to be done. I have a feeling that marjiuana, much like other things in life, could have benefits up to a certain dose. But knowing how much is too much and what a healthy dose is is key for any patients using it.


  10. It’s so great that you’re touching up on this topic! Of course people still have different opinions on marijuana, but hey if it works for patients why not use it right?
    xo, Sondra


  11. It’s really important to be educated on such a manner especially with the raising numbers of autism worldwide. I am pro using anything that can help a patient have a better quality of life.


  12. natashawashington says:

    So fascinating. It’s amazing how many uses they’re beginning to discover for medical marijuana. I still think more research is needed, but I’ve seen so many cases where it can be a huge life changing benefit to patients. Thanks for sharing!


  13. What an amazing article. I have to say that as a mom it will make me nervous to even consider introducing this to my kids. I do see how medical marijuana can be beneficial for other patients.


  14. This was a really good breakdown. I feel like the concept of cannabis (and oils) for medicinal purpose is always going to be controversial, and I don’t know if the FDA will ever officially approve it, but I always enjoy reading case studies where children have been healed of various cancers, autism symptoms, etc for its use. Thanks for sharing!


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