Emotion regulation in social anxiety disorder: exploration and neuro-modulation of underlying neural mechanisms of cognitive reappraisal

Up to 12 percent of the population experience Social Anxiety Disorder (SAD) in their lifetime, significantly impacting on quality of life. National guidance recommends Cognitive Behavioural Therapy (CBT); however, up to 40 percent of individuals experience symptoms post-treatment, with evidence for improved efficacy with a more cognitive approach. Cognitive reappraisal of negative thinking is a cognitive strategy utilised to regulate emotion. However, the neurophysiological mechanisms are not well understood.Therefore, a systematic review of the literature was completed, in which fourteen research papers were included. Methodologies utilised were varied in terms of imaging methodology, reappraisal task and sample utilised. However, the results support previous research with evidence for altered activation across the prefrontal cortices (PFC; dorso-lateral PFC, dorso-medial PFC, dorsal anterior cingulate cortex), in addition to the inferior parietal lobe and superior temporal gyrus in SAD. This may present the neural mechanisms by which cognitive reappraisal, exerts therapeutic effect in SAD, demonstrating a neural substrate consistent with the Threat Reappraisal Mediation Hypothesis.Furthermore, recent evidence suggests that transcranial direct current stimulation (tDCS) of the PFC can improve cognitive reappraisal success in healthy adults. Therefore, this study aimed to investigate the selective effects of PFC tDCS on cognitive reappraisal in adults experiencing symptoms of SAD, in comparison to active (cerebellar) and sham control groups. A secondary, exploratory aim was to investigate the effects of cerebellar tDCS on emotion recognition.Thirty-three healthy students with symptoms of social anxiety received 20-minutes of PFC, cerebellar or sham tDCS whilst completing an autobiographical social situations reappraisal task, before completing an emotion recognition task; within this multi-site, mixed, double-blind design. The main findings were that PFC and cerebellar tDCS improved cognitive reappraisal in the first trial block. Additionally, tDCS improved recognition sensitivity for happy faces and increased reaction times to angry faces. Clinical implications and suggestions for future research are discussed