PET brain imaging revealed that women with cannabis use disorder had significantly fewer CB1 receptors in key brain regions compared to female non-users, and healthy women naturally had more CB1 receptors than healthy men.
Addiction neuroscientists, sex-differences researchers, cannabis use disorder treatment developers
Healthy women had significantly higher CB1 receptor availability than healthy men across all brain regions
What the researchers found
Females with CUD (n=10) showed significantly lower CB1 receptor availability than female healthy controls (n=10) in the hippocampus, amygdala, cingulate, and insula. Among healthy controls, females had significantly higher CB1 availability than males (n=7) across all brain regions examined.
Why it matters
This is one of the first PET studies of CB1 receptors in women with cannabis use disorder. The finding that women start with higher CB1 availability but show the same pattern of downregulation as men raises questions about whether sex-specific treatment approaches are needed.
The numbers in context
10 women with CUD; 10 female healthy controls; 7 male healthy controls; significant CB1 reduction in hippocampus, amygdala, cingulate, and insula in CUD women; amygdala CB1 negatively correlated with anger/hostility during abstinence; females had higher CB1 than males across all regions.
How the study worked
PET imaging study using [11C]OMAR radiotracer comparing CB1 receptor availability between women with cannabis use disorder (after 3 days monitored abstinence) and age/BMI-matched female non-users, plus comparison between male and female healthy controls.
What this study cannot tell us
Very small sample sizes; only 3 days of monitored abstinence (may not represent full receptor recovery); cross-sectional design cannot determine if lower CB1 preceded or resulted from cannabis use; limited to one radiotracer.
How to read the evidence
Novel PET imaging study with very small samples, providing preliminary neurobiological evidence on sex differences in CB1 receptors.
When this study was published
Published in 2021.
The bigger picture
The sex difference in baseline CB1 receptor levels could help explain why women and men experience cannabis effects differently and may progress to cannabis use disorder through distinct neurobiological pathways.
Questions still open
- How long does it take for CB1 receptors to recover in women after sustained abstinence? Does the higher baseline CB1 in women affect initial sensitivity to cannabis?
Common questions
Does cannabis change the brain differently in women?
What are CB1 receptors?
Read the original research
Brain imaging of cannabinoid type I (CB1 ) receptors in women with cannabis use disorder and male and female healthy controls.
Addiction biology, 26(6), e13061
Citation
Spindle, Tory R; Kuwabara, Hiroto; Eversole, Alisha; Nandi, Ayon; Vandrey, Ryan; Antoine, Denis G; Umbricht, Annie; Guarda, Angela S; Wong, Dean F; Weerts, Elise M. (2021). Brain imaging of cannabinoid type I (CB1 ) receptors in women with cannabis use disorder and male and female healthy controls.. Addiction biology, 26(6), e13061. https://doi.org/10.1111/adb.13061
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