Despite the vast majority of evidence indicating the efficacy of traditional and recent cognitive behaviour therapy (CBT) therapies in treating social anxiety disorder (SAD), some individuals with SAD do not improve by these interventions, particularly when co-morbidity is present.

It is not clear how emotion regulation therapy (ERT) can improve SAD co-morbid with symptoms of generalized anxiety disorder (GAD) and depression. This study investigated this gap.

Treatment efficacy was assessed using a single case series methodology. Four clients with SAD co-occurring with GAD and depression symptoms received a 16-session version of ERT in weekly individual sessions. During the treatment, self-report measures and clinician ratings were used to assess the symptom intensity, model-related variables, and quality of life, work and social adjustment of participants every other week throughout the treatment. Follow-up was also conducted at 1, 2 and 3 months after treatment. Data were analysed using visual analysis, effect size (Cohen’s d) and percentage of improvement.

SAD clients with depression and GAD symptoms demonstrated statistically and clinically significant improvements in symptom severity, quality of life, work, social adjustment and model-related measures (i.e. negative emotionality/safety motivation, emotion regulation strategies). The improvements were largely maintained during the follow-up period and increased for some variables.

These findings showed preliminary evidence for the role of emotion dysregulation and motivational factors in the aetiology and maintenance of SAD and the efficacy of ERT in the treatment of co-morbid SAD.