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Background: Selective serotonin reuptake inhibitors (SSRIs) and cognitive-behavioural therapy (CBT) are often used concomitantly to treat social anxiety disorder (SAD), but few studies have examined the effect of this combination., Aims: To evaluate whether adding escitalopram to internet-delivered CBT (ICBT) improves clinical outcome and alters brain reactivity and connectivity in SAD., Method: Double-blind, randomised, placebo-controlled neuroimaging trial of ICBT combined either with escitalopram (n = 24) or placebo (n = 24), including a 15-month clinical follow-up (trial registration: ISRCTN24929928)., Results: Escitalopram+ICBT, relative to placebo+ICBT, resulted in significantly more clinical responders, larger reductions in anticipatory speech state anxiety at post-treatment and larger reductions in social anxiety symptom severity at 15-month follow-up and at a trend-level (P = 0.09) at post-treatment. Right amygdala reactivity to emotional faces also decreased more in the escitalopram+ICBT combination relative to placebo+ICBT, and in treatment responders relative to non-responders., Conclusions: Adding escitalopram improves the outcome of ICBT for SAD and decreased amygdala reactivity is important for anxiolytic treatment response., (© The Royal College of Psychiatrists 2016.)

Importance: Serotonin is involved in negative affect, but whether anxiety syndromes, such as social anxiety disorder (SAD), are characterized by an overactive or underactive serotonin system has not been established. Serotonin 1A autoreceptors, which inhibit serotonin synthesis and release, are downregulated in SAD, and serotonin transporter availability might be increased; however, presynaptic serotonin activity has not been evaluated extensively., Objective: To examine the serotonin synthesis rate and serotonin transporter availability in patients with SAD and healthy control individuals using positron emission tomography (PET) with the radioligands 5-hydroxytryptophan labeled with carbon 11 ([11C]5-HTP) and 11C-labeled 3-amino-4-(2-dimethylaminomethylphenylsulfanyl)-benzonitrile [11C]DASB., Design, Setting, and Participants: We performed a cross-sectional study at an academic clinical research center. Eighteen patients with SAD (9 men and 9 women; mean [SD] age, 32.6 [8.2] years) and 18 sex- and age-matched healthy controls (9 men and 9 women; mean [SD] age, 34.7 [9.2] years) underwent [11C]5-HTP PET imaging. We acquired [11C]DASB PET images for 26 additional patients with SAD (14 men and 12 women; mean [SD] age, 35.2 [10.7] years) and the same 18 sex- and age-matched healthy controls. Participants were recruited through newspaper advertisements. Data were acquired from March 12, 2002, through March 5, 2012, and analyzed from March 28, 2013, through August 29, 2014., Main Outcomes and Measures: The influx rate of [11C]5-HTP as a measure of serotonin synthesis rate capacity and [11C]DASB binding potential as an index of serotonin transporter availability were acquired during rest. We used the Liebowitz Social Anxiety Scale to measure severity of social anxiety symptoms., Results: The PET data were not available for analysis in 1 control for each scan. Increased [11C]5-HTP influx rate was observed in the amygdala, raphe nuclei region, caudate nucleus, putamen, hippocampus, and anterior cingulate cortex of patients with SAD compared with healthy controls (P < .05 corrected), supporting an enhanced serotonin synthesis rate. Increased serotonin transporter availability in the patients with SAD relative to healthy controls was reflected by elevated [11C]DASB binding potential in the raphe nuclei region, caudate nucleus, putamen, thalamus, and insula cortex (P < .05 corrected)., Conclusions and Relevance: Neurotransmission in SAD is characterized by an overactive presynaptic serotonin system, with increased serotonin synthesis and transporter availability. Our findings could provide important new insights into the etiology of anxiety disorders.

Social anxiety disorder (SAD) is associated with altered brain function and structure, but most structural studies include small samples and findings are mixed. This study compared regional gray matter volume between 48 SAD patients and 29 healthy controls (HC) as well as the relationship between volume and symptom severity. Structural magnetic resonance images from SAD patients and HC were evaluated using standard voxel-based morphometry (VBM) processing in the SPM8 software package. Social anxiety symptom severity was rated in SAD patients by a clinician using the Liebowitz Social Anxiety Scale (LSAS). SAD patients had greater regional gray matter volume in the lingual gyrus and lateral occipital cortex than the controls, and within the SAD group a positive correlation was found between symptom severity and regional gray matter volume in the lingual gyrus and the retrosplenial cortex. These findings replicate and extend earlier reports of enlarged visual processing areas in SAD. Increased gray matter volume in regions involved in visual processing and self-consciousness could underlie, or be the result of, abnormal emotional information processing and self-focused attention previously demonstrated in patients with SAD., (Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.)

Unlabelled: In patients with social anxiety disorder (SAD) it has been reported that selective serotonin reuptake inhibitors (SSRIs) and placebo induce anxiolytic effects by attenuating neural activity in overlapping amygdala subregions, i.e. left basolateral and right ventrolateral amygdala. However, it is not known whether these treatments inhibit amygdala subregions via similar or distinct brain pathways. As anxiolytic treatments may alter amygdala-frontal couplings we investigated differences and similarities in amygdala-frontal functional co-activation patterns between responders and nonresponders to SSRIs and placebo in patients with SAD. Positron emission tomography (PET) with oxygen-15-labeled water was used to measure anxiety-related regional cerebral blood flow in 72 patients with SAD before and after 6-8 wk of treatment under double-blind conditions. Functional couplings were evaluated with a seed region approach using voxel values from the left basolateral and right ventrolateral amygdala. Responders and nonresponders to SSRIs and placebo showed different treatment-induced co-activations between the left amygdala and the dorsolateral prefrontal cortex (dlPFC) as well as the rostral anterior cingulate cortex (ACC). Conjunction analysis suggested shared anxiolysis-dependent inverse co-activations in SSRI and placebo responders between the left amygdala-dlPFC and left amygdala-rostral ACC, and a shared positive co-activation between left amygdala-dorsal ACC. We demonstrate that amygdala-frontal co-activation patterns differentiate effective from ineffective anxiolytic treatments and that SSRI and placebo responders share overlapping neuromodulatory paths that may underlie improved emotion regulation and reduced expression of anxiety., Trial Registration: clinicaltrials.gov Identifier: NCT00343707.

Neuroimaging studies using functional magnetic resonance imaging (fMRI), positron emission tomography (PET) and single-photon emission computed tomography (SPECT) to evaluate neurofunctional and neurochemical alterations related to the generation and control of affect in patients with anxiety disorders are reviewed. We performed a meta-analysis of symptom provocation studies, where neural activity was measured using fMRI, PET or SPECT to test the hypothesis that prefrontal regions modulate amygdala activity. Data revealed that reactivity in the amygdala was enhanced in patients with phobia as well as posttraumatic stress disorder (PTSD). The dorsal anterior cingulate cortex was activated in concert with the amygdala, both in PTSD and in phobic states, suggesting a role in fear expression, rather than emotional control. Activity in emotion-regulating areas in the ventromedial prefrontal cortex including the subgenual anterior cingulate cortex and the medial orbitofrontal cortex was compromised in the symptomatic state in PTSD and phobic disorders, respectively. Increased amygdala reactivity was restored with psychological treatment. Treatment effects across different modalities including pharmacological and psychological interventions as well as with placebo regimens support that reduction of neural activity in the amygdala may be a final common pathway for successful therapeutic interventions irrespective of method, thereby linking neurotransmission to plasticity in a pivotal node of the core fear network of the brain., (Copyright © 2013 S. Karger AG, Basel.)

Background: Although the amygdala is thought to be a crucial brain region for negative affect, neuroimaging studies do not always show enhanced amygdala response to aversive stimuli in patients with anxiety disorders. Serotonin (5-HT)-related genotypes may contribute to interindividual variability in amygdala responsiveness. The short (s) allele of the 5-HT transporter linked polymorphic region (5-HTTLPR) and the T variant of the G-703T polymorphism in the tryptophan hydroxylase-2 (TPH2) gene have previously been associated with amygdala hyperresponsivity to negative faces in healthy controls. We investigated the influence of these polymorphisms on amygdala responsiveness to angry faces in patients with social anxiety disorder (SAD) compared with healthy controls., Methods: We used positron emission tomography with oxygen 15-labelled water to assess regional cerebral blood flow in 34 patients with SAD and 18 controls who viewed photographs of angry and neutral faces presented in counterbalanced order. We genotyped all participants with respect to the 5-HTTLPR and TPH2 polymorphisms., Results: Patients with SAD and controls had increased left amygdala activation in response to angry compared with neutral faces. Genotype but not diagnosis explained a significant portion of the variance in amygdala responsiveness, the response being more pronounced in carriers of s and/or T alleles., Limitations: Our analyses were limited owing to the small sample and the fact that we were unable to match participants on genotype before enrollment. In addition, other imaging techniques not used in our study may have revealed additional effects of emotional stimuli., Conclusion: Amygdala responsiveness to angry faces was more strongly related to serotonergic polymorphisms than to diagnosis of SAD. Emotion activation studies comparing amygdala excitability in patient and control groups could benefit from taking variation in 5-HT-related genes into account.

Placebo may yield beneficial effects that are indistinguishable from those of active medication, but the factors underlying proneness to respond to placebo are widely unknown. Here, we used functional neuroimaging to examine neural correlates of anxiety reduction resulting from sustained placebo treatment under randomized double-blind conditions, in patients with social anxiety disorder. Brain activity was assessed during a stressful public speaking task by means of positron emission tomography before and after an 8 week treatment period. Patients were genotyped with respect to the serotonin transporter-linked polymorphic region (5-HTTLPR) and the G-703T polymorphism in the tryptophan hydroxylase-2 (TPH2) gene promoter. Results showed that placebo response was accompanied by reduced stress-related activity in the amygdala, a brain region crucial for emotional processing. However, attenuated amygdala activity was demonstrable only in subjects who were homozygous for the long allele of the 5-HTTLPR or the G variant of the TPH2 G-703T polymorphism, and not in carriers of short or T alleles. Moreover, the TPH2 polymorphism was a significant predictor of clinical placebo response, homozygosity for the G allele being associated with greater improvement in anxiety symptoms. Path analysis supported that the genetic effect on symptomatic improvement with placebo is mediated by its effect on amygdala activity. Hence, our study shows, for the first time, evidence of a link between genetically controlled serotonergic modulation of amygdala activity and placebo-induced anxiety relief.

The amygdala is a key structure in the pathophysiology of anxiety disorders, and a putative target for anxiolytic treatments. Selective serotonin reuptake inhibitors (SSRIs) and placebo seem to induce anxiolytic effects by attenuating amygdala responsiveness. However, conflicting amygdala findings have also been reported. Moreover, the neural profile of responders and nonresponders is insufficiently characterized and it remains unknown whether SSRIs and placebo engage common or distinct amygdala subregions or different modulatory cortical areas. We examined similarities and differences in the neural response to SSRIs and placebo in patients with social anxiety disorder (SAD). Positron emission tomography (PET) with oxygen-15-labeled water was used to assess regional cerebral blood flow (rCBF) in 72 patients with SAD during an anxiogenic public speaking task, before and after 6-8 weeks of treatment under double-blind conditions. Response rate was determined by the Clinical Global Impression-Improvement scale. Conjunction analysis revealed a common rCBF-attenuation from pre- to post-treatment in responders to SSRIs and placebo in the left basomedial/basolateral and right ventrolateral amygdala. This rCBF pattern correlated with behavioral measures of reduced anxiety and differentiated responders from nonresponders. However, nonanxiolytic treatment effects were also observed in the amygdala. All subgroups, including nonresponders, showed deactivation of the left lateral part of the amygdala. No rCBF differences were found between SSRI responders and placebo responders. This study provides new insights into the brain dynamics underlying anxiety relief by demonstrating common amygdala targets for pharmacologically and psychologically induced anxiety reduction, and by showing that the amygdala is functionally heterogeneous in anxiolysis. [ABSTRACT FROM AUTHOR]

Social anxiety disorder (SAD) is associated with aberrant emotional information processing while little is known about non-emotional cognitive processing biases. The dorsal anterior cingulate cortex (dACC) has been implicated in SAD neuropathology and is activated both by emotional and non-affective cognitive challenges like the Multisource Interference Task (MSIT). Here, we used fMRI to compare dACC activity and test performance during MSIT in 69 SAD patients and 38 healthy controls. In addition to patient-control comparisons, we examined whether neural activity in the dACC correlated with social anxiety, trait anxiety or depression levels. The MSIT activated the dACC as expected but with no differences in task performance or neural reactivity between SAD patients and controls. There were no significant correlations between dACC activity and social or trait anxiety symptom severity. In patients, there was a significant negative correlation between dACC activity and depressive symptoms. In absence of affective challenge, we found no disorder-related cognitive profile in SAD patients since neither MSIT task performance nor dACC neural activity deviated in patients relative to controls. • Cognitive task performance and neural activity is unaffected in social anxiety disorder. • Anxiety severity does not correlate with dorsal anterior cingulate cortex activity. • Depressive symptoms correlate with neural activity in social anxiety disorder. [ABSTRACT FROM AUTHOR]