Autism spectrum disorder (ASD) is a term used to classify a series of complex neurodevelopmental disorders characterized, at different levels, by difficulties in social interaction, problems with verbal and physical communication, and limited and repetitive behavior patterns. Among a variety of types of ASD is autism, the most severe form of the disorder, also called “classic ASD”. Other types include Asperger’s syndrome, Childhood Disintegrative Disorder, and Pervasive Developmental Disorder, unspecified. According to the National Institute of Neurological Disorders and Stroke, one in every 88 children aged 8 years has some degree of ASD, four times more common in boys than girls.

Impairment of social interaction is the main sign of ASD and can be observed since childhood. Diagnosed children and infants may be aloof, avoid eye contact, or not respond when called by name. They can focus on an object for a long period of time without noticing any external stimulus. They have difficulty interpreting other people’s thoughts and feelings and thus have problems understanding and responding to social cues, such as facial expressions and tone of voice. It is common for them to show a lack of empathy. Repetitive movements such as spinning, rocking, or self-abusive behaviors such as biting and head banging are common in children with autism.

Early indicators of ASD include ignoring when called, little eye contact, no babbling or pointing in the first year of life, no words at 16 months, obsessive alignment of toys or other objects, and no smiling or social interaction. Later indicators include difficulties in initiating or maintaining dialogue, making friends, repetitive or unusual language, difficulty playing with the imagination, restricted patterns of focus, and the inflexible need to follow routines.

The causes of ASD are still unknown, but it appears both genetics and environment play a role, according to the National Institute of Neurological Disorders and Stroke. Irregularities in the brain and abnormal levels of neurotransmitters are commonly seen in children and infants with ASD, which suggests that the disease is caused by a disruption in normal brain development due to the presence of defects in genes that regulate communication between neurons.

There is currently no cure for ASD, so traditional treatments focus on training aimed at teaching social and language skills, medication for anxiety, depression or obsessive-compulsive behaviors.

Discoveries: effects of cannabis on autism

Researchers have discovered what they believe to be a possible link between autism and cannabinoid receptors, in particular CB2 of the endocannabinoid system 2,5,7,9. One study found that cellular mutations in the brain that had been associated with autism block the action of molecules that act on CB2 receptors. These are the same receptors that interact with the cannabinoids in cannabis – THC (tetrahydrocannabinol) and CBD (cannabidiol) 3. A similar study also found that mice with behavioral problems similar to autism had overactivated CB2 receptors 8. Another found this same prevalence in CB2 overactivation, but in humans 11. These findings related to CB2 receptors support the theory that autism could be caused by a disruption in the brain’s ability to send clear signals, thus suggesting the possibility of using the cannabinoids found in cannabis to reestablish communication, allowing normal cellular functioning 3.

There is also evidence supporting the effectiveness of cannabinoids in the treatment of autism 7,9,10. In one study, an autistic child who received THC for six months reported significant improvements in hyperactivity, lethargy, irritability, stereotypy, and speech problems 6. Additionally, mice with similar behavioral characteristics to autistic humans showed a reduction in depression and were able to remain focused by running on a spinning wheel after cannabinoid administration 8. Another study found that increased cannabinoids in the brain help remedy behavioral problems related to fragile X syndrome, the most common known genetic cause of autism. 4.

Studies on the effects of cannabis on autismo

• An autistic child who received THC for six months showed a significant reduction in the symptoms of the disease. Use of dronabinol (delta-9-THC) in autism: a prospective individual case study in childhood autism.

http://www.cannabis-med.org/data/pdf/en_2010_04_1.pdf

• Mice with behavioral characteristics similar to humans with autism demonstrated a significant reduction in depression and were able to remain focused on the task of running on a rotating wheel. Consequences of disruption of the monoaminergic and cannabinoid system in a mouse model of autism spectrum disorders.
  https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3137184/

Reference:

1. Autism Fact Sheet. (n.d.). National Institute of Neurological Disorders and Stroke. Retrieved from
   http://www.ninds.nih.gov/disorders/autism/detail_autism.htm.
2. Chakrabari, B., and Baron-Cohen, S. (2011). Variation in the human cannabinoid receptor CNR1 gene modulates gaze duration for happy faces. Molecular Autism, 2,10. Retrieved from
   https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3155489/.
3. Foldy, C., Malenka, R.C., and Sudhof, T.C. (2013, May 8). Autism-associated neuroligin-3 mutations commonly disrupt tonic endocannabinoid signaling. Neuron, 78(3), 498-509. Retrieved from
   https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3663050/.
4. Jung, K.M., Sepers, M., Henstridge, C.M., Lassalle, O., Neuhofer, D., Martin, H., Ginger, M., Frick, A., DiPatrizio, N.V., Mackie, K., Katona, I., Piomelli, D., and Manzoni, OJ. (2012). Uncoupling of the endocannabinoid signalling complex in a mouse model of fragile x syndrome. Nature Communications, 3:1080. doi: 10.1038/ncomms2045. Retrieved from
   https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3657999/.
5. Kerr, D.M., Downey, L., Conboy, M., Finn, D.P., and Roche, M. (2013). Alternations in the endocannabinoid system in the rat valproic acid model of autism. Behavioural Brain Research, 249, 124-132. Retrieved from
   http://www.sciencedirect.com/science/article/pii/S0166432813002519.
6. Kurz, R., and Blass, K. (2010). Use of dronabinol (delta-9-THC) in autism: A prospective single-case-study with an early infantile autistic child. Cannabinoids, 5(4), 4-6. Retrieved from
   https://cannabis-med.org/data/pdf/en_2010_04_1.pdf.
7. Liu, Q.T., Pan, C.H., Hishimoto, A., Li, C.Y., Xi, Z.X., Llorente-Berzal, A., Viveros, M.P., Ishiguro, H., Arinami, T., Onaivi, E.S., and Uhl, G.R. (2009). Species differences in cannabinoid receptor 2 (CNR2 gene): Identification of novel human and rodent CB2 isoforms, differential tissue expression and regulation by cannabinoid receptor ligands. Genes, Brain and Behavior, 8, 519-530. Retrieved from
   https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3389515/.
8. Onaivi, E.S., Benno, R., Halpern, T., Mehanovic, M., Schanz, N., Sanders, C., Yan, X., Ishiguro, H., Liu, Q.R., Berzal, A.L., Viveros, M.P., and Ali, S.F. (2011, March). Consequences of cannabinoid and monoaminergic system disruption in a mouse model of autism spectrum disorders. Current Neuropharmacology, 9(1), 209-14. Retrieved from
   https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3137184/.
9. Schneider, M., and Koch, M. (2005). Deficient Social and Play Behavior in Juvenile and Adult Rats after Neonatal Cortical Lesion: Effects of Chronic Pubertal Cannabinoid Treatment. Neuropsychopharmacology, 30, 944-957. Retrieved from
   http://www.nature.com/npp/journal/v30/n5/full/1300634a.html.
10. Siniscalo, D. (2014). Endocannabinoid System as Novel Therapeutic Target for Autism Treatment. Autism – Open Access, 4,2, Retrieved from
    https://www.omicsgroup.org/journals/endocannabinoid-system-as-novel-therapeutic-target-for-autism-treatment-2165-7890.1000e122.pdf.
11. Siniscalco, D., Sapone, A., Giordano, C., Cirillo, A., de Magistris, L., Rossi, F., Fasano, A., Bradstreet, J.J., Maione, S., and Antonucci, N. (2013, November). Cannabinoid receptor type 2, but not type 1, is up-regulated in peripheral blood mononuclear cells of children affected by autistic disorders. Journal of Autism and Developmental Disorders, 43(11), 2686-95. Retrieved from
    http://link.springer.com/article/10.1007/s10803-013-1824-9.
12. What Is Autism? (n.d.). Autism Speaks. Retrieved from
    https://www.autismspeaks.org/what-autism.