Neural correlates of the distortion of attentional focus in social anxiety disorder

Abstract

Social anxiety disorder is characterized by heightened anxiety and avoidance of social situations. Emotional and physiological anxiety reaction in social anxiety disorder is known to be triggered by cognitive distortions that automatically appear in social situations. The present study aimed to elucidate the neural basis of attentional bias toward internal and external threats as a core element of social anxiety. In addition, this study aimed to investigate serotonin-1A receptor binding potentials in social anxiety disorder to figure out the association between the distortion of attentional focus and serotonin, which has a pivotal role in the modulation of anxiety and fear reactions. The modified face-in-the-crowd-effect task was performed by 22 patients with social anxiety disorder and 20 comparison subjects while undergoing functional magnetic resonance imaging (fMRI). Participants were instructed to find contempt face among angry or happy faces of the crowd with different levels of internal threat (participants’ own pulse-sound versus control-sound) and external threat (8-crowd versus 4-crowd of faces). Fifteen patients with social anxiety disorder and 15 comparison subjects underwent positron emission tomography (PET) scanning with the 18F-FCWAY. The 2 x 2 (internal x external factor) repeated measures analyses of variance in each group showed that the accuracy of the patient group revealed significant internal x external interaction effect and main effects for these factors. The accuracy of the comparison group was shown significant main effects for the internal and the external factors, but no interaction effect. The fMRI result showed that the patient group revealed main effect of internal threat in the orbitofrontal cortex, insula, and rostral anterior cingulate cortex, main effect of external threat and interaction effect in the posterior cingulate cortex. The comparison group showed main effect of internal threat and interaction effect in the temporo-parietal junction, but no main effect of external threat. The orbitofrontal activity, during the internal and external attention with the modified face-in-the-crowd-effect task, positively correlated with the level of depression and negatively correlated with the level of global functioning in patients. In addition, there were significant associations between the insular activity and the severity of social anxiety, and between the anterior cingulate activity and the level of fear of negative evaluation. The PET result showed greater binding potentials of serotonin-1A receptor in midline structures, such as the orbitofrontal, anterior cingulate, and frontopolar cortices. Behavioral results imply the interactive process of internal and external focus of attention throughout the course of social situationss. The fMRI results of distinctive neural activity on the limbic and paralimbic system during self-focused attention and attentional bias toward external threats suggest the role of the orbitofrontal cortex, insula, and anterior cingulate cortex as compensatory response, anxiety reaction related to self-focused attention, and distorted cognitive control, respectively, in patient with social anxiety disorder. Finally, the PET results of increased binding potentials in these regions support the role of serotonin-1A receptor on the distortion of attentional focus in patients with social anxiety disorder.