Men With Opioid Use Disorder Had 15% Lower Brain Cannabis Receptor Levels
A brain imaging study found that men with opioid use disorder on stable treatment had 15% lower CB1 receptor availability than healthy controls, particularly in emotion-regulating brain regions.
Quick Facts
What This Study Found
Average CB1R availability (measured by volume of distribution) was 15% lower across 13 brain regions in men with OUD compared to healthy controls (p=0.04). Lower CB1R was also observed in several corticolimbic areas. No effects on CB1R were found for treatment medication type, stress levels, antidepressant use, treatment duration, or time since last illicit opioid use.
Key Numbers
n=10 OUD patients, n=18 healthy controls; 15% lower average CB1R volume of distribution (p=0.04); 13 brain regions assessed; no effect of treatment medication type or duration.
How They Did This
PET brain imaging study using High-Resolution Research Tomography and the CB1R-specific radiotracer [11C]OMAR, comparing 10 males with OUD on stable opioid agonist treatment (methadone or buprenorphine) to 18 healthy male controls. CB1R availability was measured across 13 brain regions.
Why This Research Matters
If confirmed, lower CB1R availability in OUD could provide a rationale for targeting the endocannabinoid system in opioid addiction treatment. Understanding how opioid use alters the brain's cannabinoid system may help explain why some opioid users also develop cannabis use patterns.
The Bigger Picture
The endocannabinoid system has been proposed as a target for developing new OUD medications. This is one of the first human brain imaging studies to directly measure CB1R in people with OUD, providing biological evidence for endocannabinoid system involvement in opioid addiction.
What This Study Doesn't Tell Us
Very small sample (n=10 OUD). Males only, limiting generalizability. All OUD participants were on opioid agonist treatment, so findings may reflect treatment effects rather than OUD itself. Cross-sectional design cannot determine whether lower CB1R preceded or resulted from opioid use.
Questions This Raises
- ?Would CB1R differences be similar in women with OUD?
- ?Is lower CB1R a cause or consequence of opioid use?
- ?Could CB1R availability predict treatment response in OUD?
Trust & Context
- Key Stat:
- 15% lower CB1 receptor availability in the brains of men with opioid use disorder
- Evidence Grade:
- Preliminary: Very small sample (n=10 OUD patients) in a pilot PET imaging study; findings require replication in larger, more diverse populations.
- Study Age:
- Published in 2025 (preprint).
- Original Title:
- A Preliminary Investigation of Brain Cannabinoid Receptor Type 1 (CB1R) Availability in Men with Opioid Use Disorder.
- Published In:
- Research square (2025)
- Authors:
- Nia, Anahita Bassir, Aghaei, Ardavan Mohammad, Weleff, Jeremy(2), Shi, Julia, Contreras, Angelina, Griffin, Mackenzie, Jegede, Oluwole, Pittman, Brian, Harpaz-Rotem, Ilan, Hillmer, Ansel, D'Souza, Deepak
- Database ID:
- RTHC-07253
Evidence Hierarchy
A snapshot of a population at one point in time.
What do these levels mean? →Frequently Asked Questions
What are CB1 receptors?
CB1 receptors are the main cannabinoid receptors in the brain. They are part of the endocannabinoid system and are involved in mood, reward, pain, and stress regulation. Both cannabis and the body's own endocannabinoids act on these receptors.
How does this relate to cannabis use?
The study did not involve cannabis use, but measured the same brain receptors that cannabis targets. Finding that these receptors are altered in opioid addiction suggests the endocannabinoid system may be involved in multiple types of substance use disorders and could be a treatment target.
Read More on RethinkTHC
- cannabis-dependence-physical-psychological-addiction-science
- cannabis-perception-vs-evidence-gap
- cannabis-use-disorder-test
- cross-addiction-quit-weed-start-drinking
- is-weed-addictive
- is-weed-addictive-science
- quitting-weed-and-alcohol
- rehab-for-weed-addiction-necessary
- signs-of-cannabis-use-disorder
- weed-vape-pen-addiction
Cite This Study
https://rethinkthc.com/research/RTHC-07253APA
Nia, Anahita Bassir; Aghaei, Ardavan Mohammad; Weleff, Jeremy; Shi, Julia; Contreras, Angelina; Griffin, Mackenzie; Jegede, Oluwole; Pittman, Brian; Harpaz-Rotem, Ilan; Hillmer, Ansel; D'Souza, Deepak. (2025). A Preliminary Investigation of Brain Cannabinoid Receptor Type 1 (CB1R) Availability in Men with Opioid Use Disorder.. Research square. https://doi.org/10.21203/rs.3.rs-7715611/v1
MLA
Nia, Anahita Bassir, et al. "A Preliminary Investigation of Brain Cannabinoid Receptor Type 1 (CB1R) Availability in Men with Opioid Use Disorder.." Research square, 2025. https://doi.org/10.21203/rs.3.rs-7715611/v1
RethinkTHC
RethinkTHC Research Database. "A Preliminary Investigation of Brain Cannabinoid Receptor Ty..." RTHC-07253. Retrieved from https://rethinkthc.com/research/nia-2025-a-preliminary-investigation-of
Access the Original Study
Study data sourced from PubMed, a service of the U.S. National Library of Medicine, National Institutes of Health.
This study breakdown was produced by the RethinkTHC research team. We analyze and report published research findings without making health recommendations. All interpretations are based solely on the published abstract and study data.