PET imaging studies found altered CB1 receptor binding in cannabis use disorder, alcohol use disorder, schizophrenia, PTSD, and eating disorders, with cannabis users showing decreased binding that normalizes with abstinence.
Neuroscience researchers, psychiatrists, and anyone interested in how the brain's cannabinoid system relates to mental health.
Cannabis-related CB1 decreases normalized with short-term abstinence
What the researchers found
Cannabis users consistently had decreased CB1 receptor binding compared to controls, normalizing after short abstinence periods. Alcohol use disorder and schizophrenia showed inconsistent results (some studies finding increased, others decreased binding). Preliminary evidence of altered CB1 binding was also found in anorexia nervosa and PTSD.
Why it matters
This review consolidates brain imaging evidence that the endocannabinoid system is disrupted across a wide range of psychiatric disorders, not just cannabis-related conditions. This supports the endocannabinoid system as a transdiagnostic treatment target.
The numbers in context
Five psychiatric disorders studied via PET: cannabis use disorder, alcohol use disorder, schizophrenia, PTSD, eating disorders. Cannabis users: consistent CB1 decrease. Alcohol/schizophrenia: inconsistent results.
How the study worked
Comprehensive review of PET imaging studies comparing endocannabinoid signaling (primarily CB1 receptor binding) between psychiatric patients and healthy controls across five disorder categories.
What this study cannot tell us
Most studies used CB1 radiotracers, limiting assessment of other endocannabinoid components. Small sample sizes in many PET studies. Inconsistent findings in some disorders make it hard to draw firm conclusions.
How to read the evidence
Moderate: comprehensive systematic review of PET imaging studies, limited by small sample sizes in original studies.
When this study was published
Published in 2019.
The bigger picture
The normalization of CB1 binding after cannabis abstinence suggests the brain's endocannabinoid system can recover, which is an encouraging finding for people trying to quit.
Questions still open
- Would targeting the endocannabinoid system with medications benefit multiple psychiatric disorders? How long does it take for CB1 binding to fully normalize after cannabis cessation? Could PET imaging predict treatment response?
Common questions
What does decreased CB1 binding mean?
How quickly does the brain recover after quitting cannabis?
Read the original research
Endocannabinoid signaling in psychiatric disorders: a review of positron emission tomography studies.
Acta pharmacologica Sinica, 40(3), 342-350
Citation
Sloan, Matthew E; Grant, Caroline W; Gowin, Joshua L; Ramchandani, Vijay A; Le Foll, Bernard. (2019). Endocannabinoid signaling in psychiatric disorders: a review of positron emission tomography studies.. Acta pharmacologica Sinica, 40(3), 342-350. https://doi.org/10.1038/s41401-018-0081-z
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