See figure 4. The DCS group had a significant improvement in OCD symptoms assessed by the Y-BOCS as compared with the placebo group at mid-treatment, with large effect size. However, there was no statistically significant difference between groups after treatment and at the 1-month follow-up. Also, the DCS group showed significant reduction of depression symptoms at the end of treatment, with large effect size. However, there was no statistically significant difference between the groups at mid-treatment and 1-month follow-up. Storch et al. found no statistically significant difference between the comparison groups although reduction of symptoms occurred in both groups. Three controlled trials with patients with specific phobia were identified: two with acrophobia and one with snake phobia. One of the studies with acrophobia reported positive results. The other study with acrophobia and the one study with snake phobia reported negative results. The study by Ressler et al. was the first to use DCS to facilitate extinction of fear in humans; it was also the only one that used virtual reality and psychophysiological measures. Twenty-seven participants were randomized to three groups: placebo plus Virtual Reality Exposure therapy, 50 mg of DCS plus VRE therapy, or 500 mg of DCS plus VRE therapy. The two sessions of behavioral exposure Folinic acid calcium salt pentahydrate therapy were performed using virtual reality: exposure to height within a virtual glass elevator. The doses of DCS or placebo were administered acutely prior to each of the two sessions. Besides subjective and psychometric measures, an objective measure of fear electrodermal skin fluctuation was used as well. Participants who received exposure therapy plus DCS showed significantly greater reduction in symptoms of acrophobia in almost all primary outcome measures – Acrophobia Questionnaire with Avoidance and Attitudes Toward Heights Inventory. There was no statistically significant difference in the outcomes between the group that received 50 mg and the group that received 500 mg. The participants who received DCS showed higher proportions of individuals who reported ����much improvement���� or ����very much improvement����, significant reduction in number of skin PD-166866 (PD166866) conductance fluctuations per minute of virtual exposure and significantly greater improvements in measures of symptoms of acrophobia in the real world.