Can medical cannabis reduce autism-like behaviors in a genetic mouse model? | Research

The takeaway

Long-term oral treatment with CBD-enriched cannabis oil reduced anxiety and decreased repetitive grooming by over 70% in a Shank3 autism mouse model, with evidence suggesting THC, not CBD alone, drove the behavioral improvements.

Families and clinicians exploring cannabis for autism, and researchers investigating the relative roles of THC versus CBD in neurodevelopmental conditions.

70% reduction in repetitive grooming

What the researchers found

CBD-enriched medical cannabis oil reduced repetitive grooming by over 70% and alleviated anxiety in Shank3 mutant mice. The effects involved CB1 receptor signaling and reduced cerebrospinal fluid glutamate levels. RNA sequencing revealed changes in neurotransmission-related gene expression. Importantly, the results questioned the relevance of CBD enrichment, suggesting THC was the critical component for treating core ASD symptoms.

Why it matters

No approved treatments exist for the core symptoms of autism. Finding that medical cannabis reduces both repetitive behavior and anxiety in a genetically relevant autism model is significant, especially the insight that THC rather than CBD may be the more important therapeutic component.

The numbers in context

Over 70% reduction in repetitive grooming; reduced CSF glutamate; CB1 receptor involvement confirmed; RNA sequencing showed neurotransmission gene changes; THC appeared more important than CBD for behavioral effects

How the study worked

Controlled animal study using Shank3 mutant mice (a human mutation-based autism model). Long-term oral treatment with CBD-enriched medical cannabis oil (Avidekel). Behavioral testing for anxiety and repetitive behaviors. Biochemical analysis of CB1R signaling, CSF glutamate, and RNA sequencing of cerebellar tissue.

What this study cannot tell us

Animal model of one specific autism-causing mutation (Shank3); autism has hundreds of genetic causes. Mouse behavior does not fully model human ASD. Single cannabis formulation tested.

How to read the evidence

Well-designed animal study with genetic autism model, multiple outcome measures, and RNA sequencing, but preclinical only.

When this study was published

Published in 2021; clinical trials of cannabis for autism are ongoing.

The bigger picture

The clinical interest in CBD for autism has far outpaced the evidence, partly because CBD is perceived as safer than THC. This study's finding that THC may be more therapeutically relevant challenges the CBD-first approach and suggests the non-intoxicating component alone may not be sufficient.

Questions still open

Would THC-dominant formulations be more effective than CBD-dominant ones for autism? Can the glutamate reduction explain the behavioral improvements? How do these findings translate to the diverse genetic landscape of human ASD?

Common questions

Can cannabis help with autism?

In this genetic mouse model, medical cannabis oil reduced repetitive behaviors by over 70% and alleviated anxiety. However, these are animal findings and clinical trials in humans are still ongoing.

Is CBD or THC better for autism?

Despite using a CBD-enriched formulation, the researchers found evidence that THC was the more important component for reducing repetitive and social behavior deficits. This challenges the common preference for CBD-only products in autism.

Read the original research

Behavioral aspects and neurobiological properties underlying medical cannabis treatment in Shank3 mouse model of autism spectrum disorder.

Translational psychiatry, 11(1), 524

View on PubMed ↗Publisher’s paper ↗

Citation

Poleg, Shani; Kourieh, Emad; Ruban, Angela; Shapira, Guy; Shomron, Noam; Barak, Boaz; Offen, Daniel. (2021). Behavioral aspects and neurobiological properties underlying medical cannabis treatment in Shank3 mouse model of autism spectrum disorder.. Translational psychiatry, 11(1), 524. https://doi.org/10.1038/s41398-021-01612-3