THC and CBD had opposing effects on how people read emotions in faces, but evidence is limited
A systematic review of 7 experiments found THC impaired or did not change facial emotion recognition, while CBD improved performance and counteracted THC effects, with opposing brain activation patterns for threatening faces.
Quick Facts
What This Study Found
Across 7 experiments (170 total participants), THC (7.5-15 mg) had no effect in 3 experiments and reduced facial emotion recognition in 3 others. CBD had no effect in 2 experiments but improved performance and counteracted THC effects in one. THC (≥10 mg) and CBD (600 mg) showed opposing effects on brain activation, skin conductance, and anxiety when viewing negative/threatening faces.
Key Numbers
7 experiments; 170 participants; THC 7.5-15 mg; CBD 600 mg; THC impaired REFE in 3 of 6 experiments; CBD improved in 1 of 3; opposing brain activation for threatening faces.
How They Did This
Systematic review (PROSPERO registered: CRD42019135085) of controlled trials assessing THC and/or CBD effects on recognition of emotions in facial expressions (REFE), searching standard databases.
Why This Research Matters
Impaired emotion recognition is a feature of anxiety and depression. If THC worsens and CBD improves this ability, it provides a mechanistic explanation for why THC can worsen anxiety while CBD may reduce it.
The Bigger Picture
The ability to accurately read emotions is fundamental to social functioning. THC impairing this while CBD improves it aligns with broader patterns: THC disrupts social cognition while CBD may enhance it. This has implications for both recreational and therapeutic use.
What This Study Doesn't Tell Us
Only 7 experiments (very limited data); small total sample (170); heterogeneous THC and CBD doses; mostly acute single-dose studies; REFE tasks vary across studies; limited to healthy volunteers.
Questions This Raises
- ?Does chronic cannabis use permanently alter emotion recognition?
- ?Would CBD pre-treatment prevent THC-induced social cognition impairment?
Trust & Context
- Key Stat:
- THC and CBD showed opposing effects on emotion recognition and brain response to threatening faces
- Evidence Grade:
- Moderate: registered systematic review of controlled trials, but very few studies (7 experiments) with small samples.
- Study Age:
- Published 2020.
- Original Title:
- The effects of Cannabidiol (CBD) and Delta-9-Tetrahydrocannabinol (THC) on the recognition of emotions in facial expressions: A systematic review of randomized controlled trials.
- Published In:
- Neuroscience and biobehavioral reviews, 118, 236-246 (2020)
- Authors:
- Rossi, Giordano Novak(2), Osório, Flávia L(2), Morgan, Celia J A(10), Crippa, José Alexandre S, Bouso, José Carlos, Rocha, Juliana Mendes, Zuardi, Antônio W, Hallak, Jaime E C, Santos, Rafael G Dos
- Database ID:
- RTHC-02809
Evidence Hierarchy
Analyzes all available research on a topic using a structured method.
What do these levels mean? →Frequently Asked Questions
Does cannabis affect how you read emotions?
THC impaired facial emotion recognition in half the experiments reviewed, while CBD improved it in one study and counteracted THC effects. They also showed opposing brain activation patterns when viewing threatening faces.
Why does this matter for anxiety?
Accurately reading emotions is essential for social interaction. THC making people worse at recognizing emotions, especially threatening ones, may contribute to social anxiety and paranoia. CBD improving this recognition could explain its anxiolytic effects.
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Cite This Study
https://rethinkthc.com/research/RTHC-02809APA
Rossi, Giordano Novak; Osório, Flávia L; Morgan, Celia J A; Crippa, José Alexandre S; Bouso, José Carlos; Rocha, Juliana Mendes; Zuardi, Antônio W; Hallak, Jaime E C; Santos, Rafael G Dos. (2020). The effects of Cannabidiol (CBD) and Delta-9-Tetrahydrocannabinol (THC) on the recognition of emotions in facial expressions: A systematic review of randomized controlled trials.. Neuroscience and biobehavioral reviews, 118, 236-246. https://doi.org/10.1016/j.neubiorev.2020.07.034
MLA
Rossi, Giordano Novak, et al. "The effects of Cannabidiol (CBD) and Delta-9-Tetrahydrocannabinol (THC) on the recognition of emotions in facial expressions: A systematic review of randomized controlled trials.." Neuroscience and biobehavioral reviews, 2020. https://doi.org/10.1016/j.neubiorev.2020.07.034
RethinkTHC
RethinkTHC Research Database. "The effects of Cannabidiol (CBD) and Delta-9-Tetrahydrocanna..." RTHC-02809. Retrieved from https://rethinkthc.com/research/rossi-2020-the-effects-of-cannabidiol
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.