Anxiolytic effect of cannabidiol in subjects with social anxiety disorder

Introduction: Generalized Social Anxiety Disorder (SAD) is one of the most common anxiety conditions, with lifetime prevalence estimates of 7-12% of the general population[1]. SAD is characterized by excessive and persistent fear and anxiety avoidance of a wide variety of social situations[2]. Cannabidiol (CBD), one major non-psychotomimetic compound from the Cannabis sativa, has shown anxiolytic effects both in animals and in human studies[3]. Objective: The objective of the present study was to evaluate the anxiolytic effects of cannabidiol in volunteers with social anxiety disorder (SAD) submitted to the simulation of public speaking test (SPST). Method: 24 subjects with generalized SAD and 12 healthy controls subjects were selected. All participants were undergraduate students, never treated (either by pharmacotherapy or psychotherapy) and without any other concomitant psychiatric disorder. Informed consent was obtained from each subject. The protocol was approved by the local Ethical Committee. The subjects were randomly allocated into three experimental groups: 1) 12 SAD subjects received CBD 600 mg (SAD-CBD); 2) 12 SAD subjects received placebo (SAD-PLAC) and 3) 12 healthy controls (HC). The groups were matched according to gender, age, years of education and socioeconomic level. Each volunteer participated in only one experimental session. Subjective ratings on the Visual Analogue Mood Scale (VAMS) and Negative Self-Statement scale (SSPS-N) were applied at six different time points, during SPST. After a 15min adaptation period, baseline measurements (B) were taken followed by a single dose of oral cannabidiol or placebo, in a double-blind procedure. Pre-stress measurements (P) were made after 80min the drug ingestion. Immediately thereafter the subjects received the instructions and had 2 minutes to prepare a 4 minutes speech about "the public transportation system of your city". Anticipatory speech measurements (A) were taken before the subject started speaking. The speech was interrupted in the middle, and speech measurements (S) were taken. Poststress measurements (F1 and F2) were made 15 and 35min after the end of the speech, respectively. The results were submitted to a repeated measures analysis of variance (ANOVA). Whenever a significant phase by group interaction occurred, comparisons among groups were made at each phase using one-factor ANOVA followed by multiple comparisons with the Bonferroni's test. Results: The increased of VAMS anxiety factor scores were significantly higher for the SAD-PLAC in relation to HC in the A, S, and F1 measures. The SAD-CBD showed an intermediate score that differed significantly from the SAD-PLAC and HC during the phase S. The scores of the SSPS-N evidenced significant differences between SAD-PLAC and SAD-CBD at the A and S phases and between SAD-PLAC and HC at the S phases. No significant differences were observed between SAD-CBD and HC. Conclusion: The increase in anxiety induced by the SPST on subjects with SAD was mitigated by the CBD, making a similar response by the HC in some measures.