Increasing anandamide levels by blocking its breakdown enzyme completely reversed social impairment in two different mouse models of autism, with the effect mediated through CB1 receptors.
Read this if you or someone you know has autism and you want to understand emerging research on endocannabinoid-based treatments.
FAAH inhibition completely reversed social impairment in two different autism mouse models.
What the researchers found
Researchers tested whether enhancing the endocannabinoid system could correct the core social impairment seen in autism spectrum disorder (ASD). They used URB597, a compound that increases anandamide levels by blocking the enzyme (FAAH) that breaks it down.
The results were striking: FAAH inhibition completely reversed social impairment in both the BTBR mouse model (a widely used autism model) and the fmr1 knockout mouse (a model of Fragile X Syndrome, the most common genetic cause of autism).
The social improvement was blocked by a CB1 receptor antagonist, confirming the mechanism operates through the endocannabinoid system. The effect was likely independent of anxiety changes, as FAAH inhibition did not alter BTBR mouse behavior in an anxiety test.
This builds on the researchers' earlier discovery that anandamide mediates the social reward effects of oxytocin, the "social bonding" hormone, through the endocannabinoid system.
Why it matters
Autism spectrum disorder currently has no pharmacological treatment for its core symptom: social impairment. The finding that endocannabinoid enhancement reversed social deficits in two different genetic models suggests a potentially broad therapeutic approach that addresses the core of ASD rather than peripheral symptoms.
The numbers in context
URB597 completely reversed social impairment in both BTBR and fmr1-/- mice. CB1 receptor blockade prevented the prosocial effect. No change in anxiety behavior (elevated plus maze) in BTBR mice treated with URB597.
How the study worked
Two mouse models of ASD were tested: BTBR mice and fmr1-/- mice (Fragile X model). Social behavior was assessed using the three-chambered social approach test, a standard paradigm measuring preference for social interaction. URB597 (FAAH inhibitor) was administered to increase anandamide levels. The CB1 receptor antagonist rimonabant was used to confirm receptor specificity. The elevated plus maze tested anxiety independently.
What this study cannot tell us
Mouse models of autism, while useful, cannot fully capture the complexity of human ASD. The three-chambered test measures social approach, which is only one aspect of social behavior. FAAH inhibitors have not been tested for social behavior in humans with ASD. The study used acute drug administration, not chronic treatment.
How to read the evidence
Moderate evidence from well-controlled animal experiments using two independent ASD models with pharmacological confirmation of the mechanism.
When this study was published
Published in 2016. Clinical investigation of endocannabinoid-based treatments for ASD social impairment is in early stages.
The bigger picture
The connection between oxytocin, anandamide, and social reward represents a mechanistic framework that could transform ASD treatment. If the endocannabinoid system mediates social bonding through oxytocin, then pharmacologically enhancing this system could address the neurobiological root of social impairment rather than managing symptoms.
Questions still open
- Would FAAH inhibitors improve social behavior in humans with ASD? Could CBD, which increases anandamide levels through a different mechanism, have similar effects? Would chronic treatment sustain the social improvement or would tolerance develop? Is this mechanism specific to ASD or would it enhance social behavior generally?
Common questions
Could cannabis-based treatments help autism?
How does the endocannabinoid system relate to autism?
Read the original research
Enhancement of Anandamide-Mediated Endocannabinoid Signaling Corrects Autism-Related Social Impairment.
Cannabis and cannabinoid research, 1(1), 81-89
Citation
Wei, Don; Dinh, Drake; Lee, DaYeon; Li, Dandan; Anguren, Allison; Moreno-Sanz, Guillermo; Gall, Christine M; Piomelli, Daniele. (2016). Enhancement of Anandamide-Mediated Endocannabinoid Signaling Corrects Autism-Related Social Impairment.. Cannabis and cannabinoid research, 1(1), 81-89. https://doi.org/10.1089/can.2015.0008
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