Transdiagnostic cognitive behavioural therapy

KEYWORDS:

• Transdiagnostic
• unified
• comorbidity
• CBT

In 1999, while a young doctoral student at the University of Nebraska-Lincoln under the tutelage of Professor Debra Hope, I began working on the framework of what would become my dissertation. The seeds for this idea were planted a year earlier by a fellow lab member, and now Associate Professor, Melanie VanDyke, and involved treating individuals with different anxiety disorder diagnoses together using the same cognitive behavioural therapy (CBT) group protocol. However, this idea was quite heretical as it deviated from the established idea that each of the DSM-IV anxiety disorder diagnoses was distinct (although related). This point was quite firmly noted by more than a few manuscript and grant application reviewers at the time. Even so, the dissertation project, a small randomised controlled trial (RCT) comparing this new transdiagnostic CBT against waitlist control, was completed in 2002, defended in 2003, and published in 2005 after convincing enough anonymous manuscript reviewers and journal editors that it was not a completely terrible idea after all (Norton & Hope, 2005).

Now, over two decades later, the difficulty has shifted from convincing reviewers that an efficacy trial of transdiagnostic CBT is a good idea, to convincing them that it is a novel idea. A very superficial literature search identifies over two dozen randomised controlled efficacy trials, including multiple RCTs directly comparing the efficacy of transdiagnostic and diagnosis-specific CBT for anxiety disorders in face-to-face (Barlow et al., 2017; Norton & Barrera, 2012) and internet-delivered formats (Dear et al., 2016, 2015; Fogliati et al., 2016; Newby et al., 2017; Titov et al., 2015), as well as multiple meta-analyses (e.g., Newby et al., 2015; Păsărelu et al., 2017; Pearl & Norton, 2017). As such, many transdiagnostic research teams have shifted their focus from efficacy to investigations of effectiveness in community or primary care settings (e.g., Cano-Vindel et al., 2021; Roberge et al., 2020), as well as studies of cost-effectiveness (e.g., Chapdelaine et al., 2021), mediators and mechanisms (e.g., Newby et al., 2014; Talkovsky & Norton, 2018), client and therapist perspectives of treatment acceptability (e.g., Smith et al., 2013), and dissemination and implementation (e.g., Gros et al., 2017). The primary purpose of this special issue is to provide a forum for the systematic presentation of theory, empirical evidence, and directions for future work as it pertains to the future of transdiagnostic CBT for the treatment of anxiety and emotional disorders.

The first paper in this special issue, by Plamondon and Provencher (2022), reports on the results of an open clinical effectiveness and feasibility trial of a transdiagnostic CBT for anxiety disorders in a mental health hospital outpatient clinic. Real-world clinical effectiveness studies, as opposed to tightly controlled efficacy trials, such as this, are a critical next-step in determining not only whether, but under what conditions, transdiagnostic CBT can be effectively transported out of research-based clinics and into general practice.

The next set of papers look directly at stakeholder perspective on the acceptability and utility of transdiagnostic CBT. The first (Huynh, et al., 2022) conducted semi-structured qualitative interviews with clients who had completed transdiagnostic CBT as part of a larger published pragmatic effectiveness trial in Quebec, Canada (Roberge et al., 2020). Similarly, Christensen et al. (2022) conducted qualitative interviews with both clients and therapists following a separate transdiagnostic CBT trial in Denmark (Reinholt et al., 2021). Finally, Galea et al. (2022) report the results of a qualitative analysis of interview from 10 anxious parents who had enrolled in a trial of a transdiagnostic CBT trial in Australia that was designed to concurrently treat anxiety disorders in parent/child dyads where both have an anxiety disorder diagnosis (Galea et al., 2021). Studies of client and therapist perspectives such as these will be essential for ongoing transdiagnostic dissemination and implementation efforts, as demonstrations of efficacy or even effectiveness are of little value if either therapists will not implement the treatments or clients will not accept them.

A vast majority of the data on the efficacy or effectiveness of transdiagnostic CBT has been conducted in Western nations, which limits our ability to generalise the results in other national or cultural contexts. The fifth paper (Arai et al., 2022) tackles this limitation head on, reporting the treatment of anxiety disorders in Japan using a translated transdiagnostic CBT protocol in a case series involving six Japanese men.

Finally, in the sixth paper, Kladnitski et al. (2022) examine the potential role of several key variables, emotion dysregulation, repetitive negative thinking, and experiential avoidance, in mediating treatment effects during transdiagnostic internet CBT for anxiety and depressive disorders. Only a handful of prior studies have examined potential mediator variables in transdiagnostic CBT, which will be crucial in moving beyond “does transdiagnostic CBT work?” to “how does transdiagnostic CBT work?”.

Does transdiagnostic CBT work? The quantum of efficacy evidence indicates the answer is Yes. It works. It works at least as well as traditional CBT for specific DSM diagnoses (Barlow et al., 2017; Norton & Barrera, 2012; Pearl & Norton, 2017) and it appears to work better than traditional CBT at treating the full diagnostic picture rather than just a specific principal diagnosis (e.g., Norton et al., 2021). It works, but we should also be reminded of the words of my former colleague and friend, the late Gordon Paul, who noted that the ultimate question in psychotherapy research is not “does it work” but rather “what treatment, by whom, is most effective for this individual, with that specific problem, under which set of circumstances, and how does it come about?” (Paul, 1969, p. 44). The papers presented in this special issue provide a snapshot of the cutting-edge research to begin to answer this question.

Acknowledgments

For this Editorial and the Huynh et al. paper, Editor in Chief Dr. Bethany Wootton served as action editor. The guest editor for the special issue thanks Dr. Wootton for her efforts in this capacity.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability statement

There are no data to share.