Prof. Daniel Offen of the Sackler Faculty of Medicine at Tel Aviv University (Credit: Tel Aviv University)

Research by Israeli scientists suggests medical cannabis oil could be “effective” in alleviating compulsive and anxious behaviors of autism, according to an initial study of animal models.

According to the results of the research, led by Prof. Daniel Offen and PhD student Shani Poleg of Tel Aviv University’s Sackler Faculty of Medicine, one of the two compounds of cannabis was found to be more effective in the treatment of autism mice.

The researchers reported that they were “surprised” to find that treatment with cannabis oil that contains the tetrahydrocannabinol (THC) substance of the hemp plant showed better impact.

“Clinical trials testing cannabis treatments for autism usually involve strains containing very large amounts of CBD [cannabidiol] — due to this substance’s anti-inflammatory properties, and because it does not produce a sense of euphoria. Moreover, the strains used for treating autism usually contain very little THC, due to apprehension regarding both the euphoria and possible long-term effects,” Poleg explained. “In the second stage of our study we inquired which active substance in cannabis causes the behavioral improvement, and were surprised to discover that treatment with cannabis oil that contains THC but does not contain CBD produces equal or even better effects — both behavioral and biochemical.”

Autism is a neurodevelopmental disorder, and its main symptoms are social deficiencies and compulsive behaviors. Prof. Offen noted that since cannabis is not defined as a medication, trials have already been conducted in children and adolescents with autism without any preliminary studies, which at times has led to misinformation on the treatment.

“According to the prevailing theory, autism involves over-arousal of the brain, which causes compulsive behavior,” Poleg said. “In the lab, in addition to the behavioral results, we saw a significant decrease in the concentration of the arousing neurotransmitter glutamate in the spinal fluid — which can explain the reduction in behavioral symptoms.”

Additionally, the study suggested that CBD alone has no impact on the behavior of autism in mice, Poleg added.

Against this, the researchers observed “significant” improvement in behavioral tests following treatments with cannabis oil containing small amounts of THC. There were no long-term effects reported in cognitive or emotional tests conducted a month and a half after treatment start. The mutation, called Shank3, that caused autism in the study’s animal model is responsible for about one percent of all autism cases, the study said.

“This is of course an initial study,” Poleg stated. “But we hope that through our basic research we will be able to improve clinical treatments. Our study shows that when treating autism with medicinal cannabis oil there is no need for high contents of either CBD or THC.”

The study results were published in Translational Psychology published by Nature.