Cannabis Affects Brain Volume Differently in Males and Females, and Fitness May Help
Among 74 young people, cannabis use affected brain volume differently by sex: females showed greater volume while males showed less, and higher aerobic fitness was linked to greater brain volume regardless of cannabis use.
Quick Facts
What This Study Found
No overall brain volume differences were found between cannabis users and controls, but sex-by-cannabis interactions revealed that female users had greater frontal and temporal volumes while male users had less volume compared to same-sex controls. Higher aerobic fitness was positively associated with frontal, parietal, cerebellum, and caudate volumes.
Key Numbers
74 participants (36 users, 38 controls); 3 weeks monitored abstinence; sex-by-cannabis interactions in frontal, temporal, and paracentral volumes; female users had greater volume, male users had less; aerobic fitness positively associated with brain volume in multiple regions; abnormal volumes not linked to better cognition.
How They Did This
Cross-sectional study of 74 adolescents and young adults (36 cannabis users, 38 controls) who completed 3 weeks of monitored cannabis abstinence, aerobic fitness testing, structural MRI, and neuropsychological testing.
Why This Research Matters
The sex-specific effects on brain volume may help explain inconsistent findings in the cannabis neuroimaging literature, while the fitness association suggests aerobic exercise could potentially buffer against cannabis-related brain changes.
The Bigger Picture
The finding that aerobic fitness is associated with greater brain volume opens a potential intervention avenue, suggesting exercise programs might promote neurocognitive health in young cannabis users.
What This Study Doesn't Tell Us
Small sample size; cross-sectional design; 3 weeks abstinence may not fully eliminate acute effects; aerobic fitness measured at one time point; directionality of brain volume differences unclear.
Questions This Raises
- ?Would aerobic exercise interventions improve brain outcomes in young cannabis users?
- ?Why do female and male cannabis users show opposite brain volume patterns?
Trust & Context
- Key Stat:
- Female cannabis users showed greater brain volume while males showed less compared to same-sex controls
- Evidence Grade:
- Small cross-sectional neuroimaging study with monitored abstinence, limited by sample size and cross-sectional design.
- Study Age:
- Published in 2021 with adolescent and young adult participants.
- Original Title:
- Cannabis Use and Brain Volume in Adolescent and Young Adult Cannabis Users: Effects Moderated by Sex and Aerobic Fitness.
- Published In:
- Journal of the International Neuropsychological Society : JINS, 27(6), 607-620 (2021)
- Authors:
- Sullivan, Ryan M(9), Wallace, Alexander L(14), Wade, Natasha E(18), Swartz, Ann M, Lisdahl, Krista M
- Database ID:
- RTHC-03561
Evidence Hierarchy
A snapshot of a population at one point in time.
What do these levels mean? →Frequently Asked Questions
Does cannabis shrink the brain?
It depends on sex. In this study, male cannabis users had less brain volume than male controls, while female users actually had more volume than female controls. Neither pattern was linked to better cognitive performance.
Can exercise protect the brain from cannabis effects?
Higher aerobic fitness was associated with greater brain volume in several regions. While this study cannot prove exercise is protective, it suggests that fitness interventions for young cannabis users warrant investigation.
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Cite This Study
https://rethinkthc.com/research/RTHC-03561APA
Sullivan, Ryan M; Wallace, Alexander L; Wade, Natasha E; Swartz, Ann M; Lisdahl, Krista M. (2021). Cannabis Use and Brain Volume in Adolescent and Young Adult Cannabis Users: Effects Moderated by Sex and Aerobic Fitness.. Journal of the International Neuropsychological Society : JINS, 27(6), 607-620. https://doi.org/10.1017/S135561772100062X
MLA
Sullivan, Ryan M, et al. "Cannabis Use and Brain Volume in Adolescent and Young Adult Cannabis Users: Effects Moderated by Sex and Aerobic Fitness.." Journal of the International Neuropsychological Society : JINS, 2021. https://doi.org/10.1017/S135561772100062X
RethinkTHC
RethinkTHC Research Database. "Cannabis Use and Brain Volume in Adolescent and Young Adult ..." RTHC-03561. Retrieved from https://rethinkthc.com/research/sullivan-2021-cannabis-use-and-brain
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.