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
Authors:
Giordano Novak Rossi, Flávia L. Osório, Celia J. A. Morgan, José Alexandre S. Crippa, José Carlos Bouso, Juliana Mendes Rocha, Antônio W. Zuardi, Jaime E. C. Hallak, and Rafael G. dos Santos.
Journal:
Neuroscience and Biobehavioral Reviews
Year:
2020
About the study
The aim of this systematic review was to evaluate how THC and CBD alter the recognition of emotions in facial expressions analyzing all randomized control trials done to date regarding the effect of these substances on this measure of social cognition.
Data for this systematic review was collected in accordance with the systematic reviews and meta-analyses guidelines, and the electronic search was performed using the PubMed, Web of Science, SciELO and LiLacs databases.
The authors found only ten studies that directly evaluated the effects of these phytocannabinoids on the recognition of emotions in facial expressions. Studies showed high heterogeneity regarding route of administration, dosage, vehicle, time between administration and assessment, etc.
Abstract
Background: Tetrahydrocannabinol (THC) and cannabidiol (CBD) are phytocannabinoids being linked with modulation of anxiety and depression. The recognition of emotions in facial expressions (REFE) is impaired in these disorders. Both drugs could modulate anxiety and mood by interfering with REFE.
Methods: Thus, a systematic review of controlled trials assessing the effects of THC and CBD on REFE was performed.
Results: Ten studies describing seven distinct experiments were found (n = 170). THC (7.5-15 mg) did not alter REFE in three experiments, but reduced task performance in other three experiments. CBD did not alter REFE in two experiments, but improved task performance and counteracted the effects of THC in one experiment. THC (≥ 10 mg) and CBD (600 mg) showed opposite effects on brain activation, skin conductance, and anxiety measures with negative/threatening faces.
Conclusions: The limited number of studies precludes firm conclusions on the effects of these substances on REFE. Further controlled trials are needed to elucidate the effects of THC and CBD on REFE.
Photo by Alexandru Zdrobău on Unsplash.
Categories:
Studies & papers
, Cannabis
Tags:
cannabis
, scientific research
, study
, CBD
, medical cannabis
, THC
, social cognition
, emotion processing
, facial expressions