A meta-analysis of 45 fMRI studies found that cannabis-using youth showed altered brain activation in prefrontal and cingulate regions during cognitive tasks, with differences varying by sex, severity, and psychiatric comorbidity.
Neuroscientists, clinicians working with adolescents, parents, and policymakers concerned about youth cannabis use.
45 studies, 1,216 cannabis-using vs. 1,486 non-using youth
What the researchers found
Cannabis-using youth showed greater activation in the rostral medial prefrontal cortex during executive control tasks and decreased activation in the dorsal medial prefrontal cortex and dorsal anterior cingulate during social cognition and emotion processing, compared to non-using peers.
Why it matters
Understanding how cannabis changes brain function in young people is critical because the adolescent brain is still developing. This meta-analysis provides the most comprehensive picture to date of where those changes occur.
The numbers in context
45 fMRI studies. 1,216 cannabis-using youth vs. 1,486 non-using controls. Brain activation differences varied by sex, cannabis use disorder severity, psychiatric comorbidity, and length of abstinence.
How the study worked
Systematic review and seed-based d mapping (SDM) meta-analysis of 45 fMRI studies comparing BOLD response in 1,216 cannabis-using youth and 1,486 non-using typically developing participants.
What this study cannot tell us
Cross-sectional nature of most included studies makes it impossible to determine whether brain differences preceded or resulted from cannabis use. Heterogeneity in study designs and cannabis exposure measures.
How to read the evidence
Large meta-analysis using validated SDM methodology across 45 fMRI studies with over 2,700 participants.
When this study was published
Published in 2022.
The bigger picture
The finding that brain differences vary with sex, severity, and comorbidity suggests that youth cannabis use does not have a single uniform effect on the brain. Individual factors shape the neurological impact.
Questions still open
- Do the observed brain activation differences reverse with sustained abstinence? Are predispositional brain differences driving both cannabis use and the observed activation patterns?
Common questions
Does cannabis change the brains of young people?
Do boys and girls show the same brain changes from cannabis?
Read the original research
A Meta-Analysis of fMRI Studies of Youth Cannabis Use: Alterations in Executive Control, Social Cognition/Emotion Processing, and Reward Processing in Cannabis Using Youth.
Brain sciences, 12(10)
Citation
Hammond, Christopher J; Allick, Aliyah; Park, Grace; Rizwan, Bushra; Kim, Kwon; Lebo, Rachael; Nanavati, Julie; Parvaz, Muhammad A; Ivanov, Iliyan. (2022). A Meta-Analysis of fMRI Studies of Youth Cannabis Use: Alterations in Executive Control, Social Cognition/Emotion Processing, and Reward Processing in Cannabis Using Youth.. Brain sciences, 12(10). https://doi.org/10.3390/brainsci12101281
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