Comorbidity and Internet-Delivered Transdiagnostic Cognitive Behavioural Therapy for Anxiety Disorders

Abstract

Internet-delivered transdiagnostic anxiety interventions aim to reduce symptoms across several anxiety disorders using one treatment protocol. However, it is unclear whether comorbidity affects outcomes of such treatment. This study re-examined data from a recent randomised controlled trial (N = 129) that evaluated the efficacy of an Internet-delivered transdiagnostic cognitive behavioural therapy (iCBT) intervention for participants with principal diagnoses of generalised anxiety disorder (GAD), social phobia (SP) panic disorder and agoraphobia (PDA), of whom 72% met criteria for a comorbid anxiety disorder or depression. Participants were divided into two groups based on whether or not they had a comorbid disorder before treatment. Participants with comorbid conditions reported higher symptom levels at pre-treatment, post-treatment, and follow-up across a range of measures. Both groups showed significant reductions in symptoms over treatment; however, participants with comorbid disorders showed greater reductions in measures of GAD, PDA, SP, depression, and neuroticism. In addition, treatment significantly reduced the number of comorbid diagnoses at follow-up. These results indicate transdiagnostic iCBT protocols have the potential to reduce comorbidity.

Keywords:

• Internet-delivered cognitive behavioural therapy
• randomised controlled trial
• anxiety
• transdiagnostic
• treatment
• Internet
• comorbidity

Acknowledgements

The authors gratefully acknowledge the participants for their involvement and helpful comments, and the National Health and Medical Research Council of Australia (Dora Lush Priority PhD scholarship), the New South Wales Institute of Psychiatry, and the Australian Rotary Health Research Fund for their financial support of this study.