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Expectancy effects on serotonin and dopamine transporters during SSRI treatment of social anxiety disorder: a randomized clinical trial

ABSTRACT: It has been extensively debated whether selective serotonin reuptake inhibitors (SSRIs) are more efficacious than placebo in affective disorders, and it is not fully understood how SSRIs exert their beneficial effects. Along with serotonin transporter blockade, altered dopamine signaling and psychological factors may contribute. In this randomized clinical trial of participants with social anxiety disorder (SAD) we investigated how manipulation of verbally-induced expectancies, vital for placebo response, affect brain monoamine transporters and symptom improvement during SSRI treatment. Twenty-seven participants with SAD (17 men, 10 women), were randomized, to 9 weeks of overt or covert treatment with escitalopram 20 mg. The overt group received correct treatment information whereas the covert group was treated deceptively with escitalopram, described as an active placebo in a cover story. Before and after treatment, patients underwent positron emission tomography (PET) assessments with the [11C]DASB and [11C]PE2I radiotracers, probing brain serotonin (SERT) and dopamine (DAT) transporters. SAD symptoms were measured by the Liebowitz Social Anxiety Scale. Overt was superior to covert SSRI treatment, resulting in almost a fourfold higher rate of responders. PET results showed that SERT occupancy after treatment was unrelated to anxiety reduction and equally high in both groups. In contrast, DAT binding decreased in the right putamen, pallidum, and the left thalamus with overt SSRI treatment, and increased with covert treatment, resulting in significant group differences. DAT binding potential changes in these regions correlated negatively with symptom improvement. Findings support that the anxiolytic effects of SSRIs involve psychological factors contingent on dopaminergic neurotransmission while serotonin transporter blockade alone is insufficient for clinical response.

SUBMITTER: Hjorth O

PROVIDER: S-EPMC8566580 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:Background and aimsInternet-based cognitive-behavioral therapy (iCBT) for social anxiety disorder has been found effective, as attested by independently conducted randomized controlled trials in four languages. The study aim is to test the efficacy of an iCBT program in a culture where it was not tested before (i.e. Romania).MethodsParticipants (n = 76) were recruited, screened and randomized to either a nine-week guided iCBT or a wait-list control group in April and May 2012. Self-report measures were collected before (April 2012) and after the intervention (July 2012), as well as six months later (January 2013). Although social anxiety was assessed with multiple measures, the Liebowitz Social Anxiety Scale - Self Report version (LSAS-SR) and Social Phobia Inventory (SPIN) were used as the primary outcome measures.ResultsA significant difference with a large between-group effect size in favor of iCBT was found (Cohen's d = 1.19 for LSAS-SR and d = 1.27 for SPIN). Recovery rates show that 36.8% (n = 14) in the treatment group score below the SPIN clinical cut-off compared to only 2.6% (n = 1) in the wait-list control group. Post-intervention clinical interviews also revealed that 34.2% (n = 13) of the treatment group was completely recovered (full remission) while additionally 36.8% (n = 14) retained some social anxiety symptoms (partial remission). However, an important study limitation is that post-intervention interviewers were not blinded to the study conditions. The program also effectively reduced depression and dysfunctional thinking (between-group Cohen's d = 0.84 for depression and d = 0.63 for dysfunctional thinking). Moreover, the iCBT intervention appears to have a long-term impact for participants' functioning, as the treatment gains were maintained six months later.ConclusionsInternet-delivered interventions display a high potential to quickly and widely disseminate effective evidence-based programs around the world. This study provides support for guided iCBT as a promising treatment approach in Romania.Trial registrationClinicalTrials.gov NCT01557894.

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Expectancy effects on serotonin and dopamine transporters during SSRI treatment of social anxiety disorder: a randomized clinical trial

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