The participants were invited to attend an assessment interview for possible participation in the present study. None of them were under CBT. Assessment of all of them was undertaken by psychiatrists who were trained in administering the Structured Clinical Interview for DSM-IV (SCID I and II; Liebowitz, 1987; Di Nardo et al., 1994; First et al., 1997). The participants completed the first battery of self-report measures before attending the assessment interview. The baseline period for them was a minimum of 3 weeks showing stable FNE scores (Watson and Friend, 1969; the primary outcome measure). Subsequently, after the assessment interview, they rated themselves on the FNE and LSAS (Liebowitz, 1987) over the succeeding weeks (preintervention). All of the participants had a stable FNE score over the 3 consecutive weeks and were therefore scheduled for intervention within a week after the third-baseline measuring point.
This investigation was conducted according to the principles expressed in the Declaration of Helsinki. All experimental protocols were consistent with the Guide for Experimentation with Humans and were approved by the Institutional Ethics Committee of Kyoto University (#2018-150), the regional committee for medical and health research ethics (#2018/1783), and the Japanese Data Inspectorate for clinical trials (JCT0018004564). The author obtained written informed consent from all of the participants involved in the study. Written informed consent was additionally obtained from the parent/legal guardian of all participants who were younger than the age of consent at the time of the study.
At the follow-up conducted after the completion of the intervention, none of the participants had any significant health complaint, although no systematic evaluation of side effects was conducted. At that time, among the 17 participants included in the CBD group, nine reported that they decided to receive some form of treatment (medication and CBT) by regularly visiting hospitals, while none of the 20 participants in the control group was found to make such a decision. The participants of the CBD group were more likely to make such decision than those of the placebo group were (χ 2 (1) = 13.99, p < 0.001).
Figure 2 presents the results of the measurements with LSAS of the level of the symptoms that are associated with SAD. The results were strikingly similar to those shown in Figure 1 . The main effect was statistically significant for MEASUREMENT (F1,35 = 10.35, p = 0.003, η p 2 = 0.023) but not for PARTICIPANT (F1,35 = 0.45, p = 0.57, η p 2 = 0.011). The interaction between these factors was significant (F1,35 = 39.16, p < 0.001, η p 2 = 0.528). The mean LSAS score (SD) of the CBD group was 74.2 (7.5) in the preintervention measurement and 62.1 (8.7) in the postintervention measurement and that of the placebo group was 69.9 (10.3) in the preintervention measurement and 66.8 (11.2) in the postintervention measurement.
Another post hoc test revealed that the mean LSAS score of the CBD group was lower in the postintervention measurement than in the preintervention measurement (p = 0.03), but no such difference was found in the placebo group (p = 0.42). Scores of the participants in the CBD group were smaller than those of the placebo group in the postintervention measurement (p = 0.0018), but the scores in the two groups were not statistically significantly different from one another in the preintervention measurement (p = 0.66).
Neurobiology and Developmental Biology Laboratory, School of Biosciences, Pontifical Catholic University, Porto Alegre, RS, Brazil
de Lima Osório F, Crippa JA, Loureiro SR (2007). A study of the discriminative validity of a screening tool (MINI-SPIN) for social anxiety disorder applied to Brazilian university students. Eur Psychiatry 22: 239–243.
A total of 24 subjects with generalized SAD and 12 HC subjects were selected by the screening procedure described below (see section). The SAD patients were randomly assigned to the two groups with 12 subjects each to receive CBD (600 mg—SAD-CBD) or placebo (SAD-PLAC), in a double-blind study design. To ensure the adequacy of the matching procedure, the first participant had his treatment blindly chosen between the two treatment options available; the next participant (whose characteristics were matched to the first one’s) had his treatment drawn from the remaining option. An equal number of healthy controls (n=12) performed the test without receiving any medication (HC). The groups were matched according to gender, age, years of education, and socioeconomic status. Moreover, the two SAD groups were balanced according to the Social Phobia Inventory (SPIN (Connor et al, 2000)). All participants were treatment-naïve (either with pharmacotherapy or psychotherapy) and did not present any other concomitant psychiatric disorder. No subject had a history of head trauma, neurological illness, ECT, substance abuse, or major medical illnesses, based on a semi-standardized medical questionnaire and physical examination. They were all non-smokers (of tobacco) and had not taken any medications for at least 3 months before the study. None of the subject had used marijuana more than five times in their lives (no use in the last year) and none had ever used any other illegal drug. All subjects gave written informed consent after being fully informed about the research procedure, following approval by the local ethical committee (HCRP No. 12407/2009).
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Zuardi AW, Karniol IG (1981). Transcultural evaluation of a self-evaluation scale of subjective states. J Brasileiro Psiquiatr 131: 403–406.
Blanco C, Antia SX, Liebowitz MR (2002). Pharmacotherapy of social anxiety disorder. Biol Psychiatry 51: 109–120.
Generalized Social Anxiety Disorder (SAD) is one of the most common anxiety conditions with impairment in social life. Cannabidiol (CBD), one major non-psychotomimetic compound of the cannabis sativa plant, has shown anxiolytic effects both in humans and in animals. This preliminary study aimed to compare the effects of a simulation public speaking test (SPST) on healthy control (HC) patients and treatment-naïve SAD patients who received a single dose of CBD or placebo. A total of 24 never-treated patients with SAD were allocated to receive either CBD (600 mg; n=12) or placebo (placebo; n=12) in a double-blind randomized design 1 h and a half before the test. The same number of HC (n=12) performed the SPST without receiving any medication. Each volunteer participated in only one experimental session in a double-blind procedure. Subjective ratings on the Visual Analogue Mood Scale (VAMS) and Negative Self-Statement scale (SSPS-N) and physiological measures (blood pressure, heart rate, and skin conductance) were measured at six different time points during the SPST. The results were submitted to a repeated-measures analysis of variance. Pretreatment with CBD significantly reduced anxiety, cognitive impairment and discomfort in their speech performance, and significantly decreased alert in their anticipatory speech. The placebo group presented higher anxiety, cognitive impairment, discomfort, and alert levels when compared with the control group as assessed with the VAMS. The SSPS-N scores evidenced significant increases during the testing of placebo group that was almost abolished in the CBD group. No significant differences were observed between CBD and HC in SSPS-N scores or in the cognitive impairment, discomfort, and alert factors of VAMS. The increase in anxiety induced by the SPST on subjects with SAD was reduced with the use of CBD, resulting in a similar response as the HC.
Chagas MH, Nardi AE, Manfro GG, Hetem LA, Andrada NC, Levitan MN et al (2010). Guidelines of the Brazilian medical Association for the diagnosis and differential diagnosis of social anxiety disorder. Rev Bras Psiquiatr 32: 444–452.
The anxiolytic effects of CBD had been extensively demonstrated in animal studies and in healthy volunteers submitted to anxiety induced by several procedures, including the simulation of public speaking (Crippa et al, 2010, 2011). However, there is only one published report of the anxiolytic effect of CBD in an anxiety disorder (Crippa et al, 2010, 2011). This study was performed with SAD patients and the anxiolyic effects of CBD were detected before provoking anxiety by the tracer injection and scanning procedure of SPECT, suggesting that CBD facilitates habituation of anticipatory anxiety. The SPECT analysis of this study and of a previous one with healthy volunteers (Crippa et al, 2004) showed that the CBD effects were associated with the activity of the parahippocampal gyrus and hippocampus. Functional magnetic resonance imaging (fMRI) detected attenuated responses in the amygdala and in the cingulated cortex induced by CBD (600 mg) during the viewing of fearful facial stimuli (Fusar-Poli et al, 2009a). Moreover, CBD has shown to disrupt forward intrinsic connectivity between the amygdala and the anterior cingulate during the neural response to fearful faces (Fusar-Poli et al, 2009b). Taken together, these studies demonstrate the action of CBD in limbic and paralimbic brain areas, which are known to be associated with anxiety.