Development and evaluation of an online, mindfulness-enhanced cognitive behavioural intervention for depression and anxiety in adults

Abstract

Transdiagnostic cognitive behavioural therapy delivered over the internet (iCBT) has gained empirical support as an efficacious and accessible way of providing evidence-based care to individuals with depression and anxiety disorders. However, a significant proportion of those who complete iCBT programs do not benefit, leaving room for improvement. The aim of this thesis was to explore whether integrating online mindfulness training into an existing iCBT program would enhance clinical outcomes by better targeting the transdiagnostic processes shared by depression and anxiety disorders. This aim was achieved across three clinical studies. The first pilot study demonstrated feasibility, acceptability, and positive outcomes of the new Mindfulness-Enhanced iCBT program (MEiCBT). The second study, a randomised controlled trial (RCT), showed that both the MEiCBT program and its constituents – the original iCBT program and the online mindfulness training program – were more efficacious that usual care in reducing symptoms of depression and anxiety, with small between-group differences in favour of the combined MEiCBT intervention, particularly for symptoms of depression. The results were in line with the hypothesis that iCBT containing mindfulness training would yield better clinical outcomes than standard iCBT, and showed for the first time that stand-alone mindfulness training delivered online could also be a viable and comparably efficacious transdiagnostic intervention for these emotional disorders. The third study, used data gathered during the RCT to test treatment effects of the three online programs on mindfulness, emotion regulation, repetitive negative thinking, and experiential avoidance, and to explore the role of these transdiagnostic factors in mediating treatment gains. Consistent with the hypotheses, the MEiCBT program showed large positive effects on these processes, which in turn were significant mediators of symptom improvement. Overall, this thesis showed that the new transdiagnostic MEiCBT intervention achieved large positive effects on symptoms of depression and anxiety, functional impairment, and diagnostic status, as well as the underlying processes shared by these emotional disorders, and that, pending replication with larger samples, this new online program may result in better clinical outcomes than standard iCBT.