A meta-analysis of 372 participants found that THC's effects on brain activation are dose-dependent and strongest in regions with the highest CB1 receptor expression.
Neuroscientists, pharmacologists, and clinicians interested in the neurobiological mechanisms of THC.
372 participants; THC effects scaled with dose and CB1 receptor density
What the researchers found
THC had neuromodulatory effects across a core network of brain regions central to many cognitive tasks and processes. These effects were related to dose, with greater effects in regions with higher levels of CB1 receptor expression.
Why it matters
Identifying where THC acts most strongly in the brain, and why, helps explain the wide range of cognitive effects reported by cannabis users and could inform dosing strategies for therapeutic applications.
The numbers in context
372 participants across multiple studies. Effects were strongest in regions with the highest CB1R expression and scaled with dose. CB2R expression was also investigated.
How the study worked
Meta-regression analysis of within-subject, repeated-measures fMRI studies examining acute THC effects on regional brain activation or blood flow in 372 participants under experimental conditions.
What this study cannot tell us
Meta-analysis limited to studies using acute THC challenges under experimental conditions, which may not fully represent chronic use patterns. Individual variation in receptor density was not captured.
How to read the evidence
Meta-regression analysis pooling data from multiple controlled neuroimaging studies with within-subject designs.
When this study was published
Published in 2022.
The bigger picture
By mapping THC's effects to receptor distribution, this analysis provides a biological framework for understanding why THC impairs some cognitive functions more than others.
Questions still open
- Could individual differences in CB1R density predict who is most sensitive to THC's cognitive effects? Does chronic use alter the receptor-dose relationship?
Common questions
Why does THC affect some brain regions more than others?
Does higher THC dose mean stronger brain effects?
Read the original research
Task-independent acute effects of delta-9-tetrahydrocannabinol on human brain function and its relationship with cannabinoid receptor gene expression: A neuroimaging meta-regression analysis.
Neuroscience and biobehavioral reviews, 140, 104801
Citation
Gunasekera, Brandon; Davies, Cathy; Blest-Hopley, Grace; Veronese, Mattia; Ramsey, Nick F; Bossong, Matthijs G; Radua, Joaquim; Bhattacharyya, Sagnik. (2022). Task-independent acute effects of delta-9-tetrahydrocannabinol on human brain function and its relationship with cannabinoid receptor gene expression: A neuroimaging meta-regression analysis.. Neuroscience and biobehavioral reviews, 140, 104801. https://doi.org/10.1016/j.neubiorev.2022.104801
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