Acute effects of delta-9-tetrahydrocannabinol, cannabidiol and their combination on facial emotion recognition: a randomised, double-blind, placebo-controlled study in cannabis users - PubMed (original) (raw)

Randomized Controlled Trial

Acute effects of delta-9-tetrahydrocannabinol, cannabidiol and their combination on facial emotion recognition: a randomised, double-blind, placebo-controlled study in cannabis users

Chandni Hindocha et al. Eur Neuropsychopharmacol. 2015 Mar.

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.

Keywords: Cannabidiol (CBD); Emotional processing; Endocannabinoid system; Schizotypy; Δ9-tetrahydrocannabinol (THC).

Copyright © 2014 The Authors. Published by Elsevier B.V. All rights reserved.

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Figures

Figure 1

Figure 1

Percentage accuracy for each intensity, over all emotions and single trial design. Asterisks indicate a significant drug×intensity interaction. (a) Percentage accuracy at 20%, (b) significant contrast between THC and Placebo at 40%, (c) significant contrast between CBD and Placebo at 60%, (d) percentage accuracy at 80%, (e) percentage accuracy at 100%, and (f) design of a single trial in the emotional processing task. Error bars represent standard error of the mean (±SEM).

Figure 2

Figure 2

(a) Recognition of all emotions over the different intensities. Asterisks׳ illustrate a significant drug by intensity interaction where at 40%, we found a significant contrast between placebo and THC; at 60%, a significant contrast between placebo and CBD and at 100%, no significant contrast after correction for multiple comparisons.

Figure 3

Figure 3

Subjective ratings of feeling ‘stoned’ averaged across all participants for all time points. Significant differences between cannabinoid conditions are indicated as followed: ⁎⁎⁎THC vs. placebo (_p_≤0.001); ♯♯♯THC+ vs. placebo (_p_≤0.001); †††THC vs. CBD (P<0.001); •••THC+CBD vs. CBD (p<0.001). Error bars represent standard error mean (±SEM).

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