Cannabidiol Does Not Dampen Responses to Emotional Stimuli in Healthy Adults

Abstract

Introduction: Cannabidiol (CBD) is a nonpsychoactive constituent of whole plant cannabis that has been reported to reduce anxiety-like behaviors in both pre-clinical and human laboratory studies. Yet, no controlled clinical studies have demonstrated its ability to reduce negative mood or dampen responses to negative emotional stimuli in humans. The objective of this study was to investigate the effects of CBD on responses to negative emotional stimuli, as a model for its potential anxiety-reducing effects. Materials and Methods: The study used a double-blind, placebo (PLB)-controlled, within-subjects design in which 38 healthy, drug-free participants consumed oral CBD (300, 600, and 900 mg) or PLB before completing several behavioral tasks selected to assess reactivity to negative stimuli. Dependent measures included emotional arousal to negative and positive visual stimuli, perceptual sensitivity to emotional facial expressions, attentional bias toward emotional facial expressions, and feelings of social rejection. In addition, subjective drug effects and physiological data were also gathered during each experimental session to assess drug effects. Discussion: CBD did not dampen responses to negative emotional stimuli and did not affect feelings of social rejection. The high dose of CBD (900 mg) marginally reduced attentional bias toward happy and sad facial expressions, and produced a slight increase in late-session heart rate. CBD did not produce detectable subjective effects or alterations in mood or anxiety. Conclusion: These findings indicate that CBD has minimal behavioral and subjective effects in healthy volunteers, even when they are presented with emotional stimuli. Further research into the behavioral and neural mechanisms of CBD and other phytocannabinoids is needed to ascertain the clinical function of this drug.

Keywords: behavior; cannabidiol; emotional stimuli; psychopharmacology.

FIG. 1.

Mean±SEM reaction times for emotional words in the Emotional Stroop task. Asterisk (*) indicates that both the reaction times for the negative and positive words were significantly shorter than the reaction times for the color control words, but the reaction times for the negative and positive words did not significantly differ from one another. CBD had no effect on reaction times for any words. CBD, cannabidiol; SEM, standard error of the mean.

FIG. 2.

Mean±SEM negativity ratings for (A) nonsocial and (B) social images of positive, negative, or neutral valence in the IAPS picture rating task. All image valence groups significantly differed from all other image valence groups, but CBD did not alter ratings of either positive or negative stimuli. A similar trend in positivity ratings was observed for both nonsocial and social images. IAPS, International Affective Picture System.

FIG. 3.

Mean±SEM response intensity of facial expressions at time of identification in the DEIT. Asterisk (*) indicates that participants identified angry faces significantly faster than any of the other facial emotions. None of the other facial emotions differed from one another, and CBD did not affect the ability to identify facial expressions, regardless of emotion. DEIT, Dynamic Emotion Identification Task.

FIG. 4.

Mean±SEM attentional bias scores toward angry, fearful, happy, or sad facial expressions. With all emotions taken together, CBD affected attentional bias (p=0.031). This effect of CBD was not specific to certain emotions.

FIG. 5.

Mean±SEM feelings of positive mood (A) and self-esteem (B) after the Cyberball games conditions of “accepted” and “rejected.” Asterisks (*) indicate that subjects reported reduced feelings of positive mood and self-esteem after the rejection game, but CBD did not change their responses.

FIG. 6.

Mean±SEM (A) heart rate and (B) blood pressure (BP) throughout the experimental session before and after CBD (300, 600, and 900 mg) or placebo administration. Asterisk (*) indicates that the highest dose of CBD (900 mg) resulted in a slight increase in heart rate at the last time point of the session. CBD had no effect on BP (MAP, p>0.05). MAP, mean arterial pressure.