title: Acute effects of delta-9-tetrahydrocannabinol, cannabidiol and their combination on facial emotion recognition: a randomised, double-blind, placebo-controlled study in cannabis users.
abstract: Acute administration of the primary psychoactive constituent of cannabis, Δ-9-tetrahydrocannabinol (THC), impairs human facial affect recognition, implicating the endocannabinoid system in emotional processing. Another main constituent of cannabis, cannabidiol (CBD), has seemingly opposite functional effects on the brain. This study aimed to determine the effects of THC and CBD, both alone and in combination on emotional facial affect recognition. 48 volunteers, selected for high and low frequency of cannabis use and schizotypy, were administered, THC (8mg), CBD (16mg), THC+CBD (8mg+16mg) and placebo, by inhalation, in a 4-way, double-blind, placebo-controlled crossover design. They completed an emotional facial affect recognition task including fearful, angry, happy, sad, surprise and disgust faces varying in intensity from 20% to 100%. A visual analogue scale (VAS) of feeling 'stoned' was also completed. In comparison to placebo, CBD improved emotional facial affect recognition at 60% emotional intensity; THC was detrimental to the recognition of ambiguous faces of 40% intensity. The combination of THC+CBD produced no impairment. Relative to placebo, both THC alone and combined THC+CBD equally increased feelings of being 'stoned'. CBD did not influence feelings of 'stoned'. No effects of frequency of use or schizotypy were found. In conclusion, CBD improves recognition of emotional facial affect and attenuates the impairment induced by THC. This is the first human study examining the effects of different cannabinoids on emotional processing. It provides preliminary evidence that different pharmacological agents acting upon the endocannabinoid system can both improve and impair recognition of emotional faces.
authors.affiliation: Clinical Psychopharmacology Unit, University College London, United Kingdom. Electronic address: c.hindocha@ucl.ac.uk.
authors.forename: Chandni
authors.initials: C
authors.lastname: Hindocha
authors.affiliation: Clinical Psychopharmacology Unit, University College London, United Kingdom.
authors.forename: Tom P
authors.initials: TP
authors.lastname: Freeman
authors.affiliation: Clinical Psychopharmacology Unit, University College London, United Kingdom.
authors.forename: Grainne
authors.initials: G
authors.lastname: Schafer
authors.affiliation: Clinical Psychopharmacology Unit, University College London, United Kingdom.
authors.forename: Chelsea
authors.initials: C
authors.lastname: Gardener
authors.affiliation: Clinical Psychopharmacology Unit, University College London, United Kingdom.
authors.forename: Ravi K
authors.initials: RK
authors.lastname: Das
authors.affiliation: Clinical Psychopharmacology Unit, University College London, United Kingdom; Department of Psychology, University of Exeter, United Kingdom.
authors.forename: Celia J A
authors.initials: CJ
authors.lastname: Morgan
authors.affiliation: Clinical Psychopharmacology Unit, University College London, United Kingdom.
authors.forename: H Valerie
authors.initials: HV
authors.lastname: Curran
mesh_terms: D000280:Administration, Inhalation; D002185:Cannabidiol / Q000494:pharmacology*; D018592:Cross-Over Studies; D004311:Double-Blind Method; D013759:Dronabinol / Q000494:pharmacology*; D004338:Drug Combinations; D004347:Drug Interactions; D004644:Emotions / Q000187:drug effects; D000066499:Facial Recognition / Q000187:drug effects*; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008385:Marijuana Smoking / Q000188:drug therapy / Q000523:psychology*; D010775:Photic Stimulation; D011619:Psychotropic Drugs / Q000494:pharmacology; D012569:Schizotypal Personality Disorder / Q000139:chemically induced* / Q000523:psychology; D011795:Surveys and Questionnaires; D064232:Visual Analog Scale; D055815:Young Adult
chemical_list: D004338:Drug Combinations; D011619:Psychotropic Drugs; D002185:Cannabidiol; D013759:Dronabinol
keywords: Cannabidiol (CBD); Emotional processing; Endocannabinoid system; Schizotypy; Δ9-tetrahydrocannabinol (THC)