The Expanding Cognitive-Behavioural Therapy Treatment Umbrella for the Anxiety Disorders: Disorder-Specific and Transdiagnostic Approaches

Abstract

Cognitive-behavioural therapy (CBT) is an empirically supported treatment for anxiety disorders. CBT treatments are based on disorder-specific protocols that have been developed to target individual anxiety disorders, despite that anxiety disorders frequently co-occur and are comorbid with depression. Given the high rates of diagnostic comorbidity, substantial overlap in dimensional symptom ratings, and extensive evidence that the mood and anxiety disorders share a common set of psychological and biological vulnerabilities, transdiagnostic CBT protocols have recently been developed to treat the commonalities among the mood and anxiety disorders. We conducted a selective review of empirical developments in the transdiagnostic CBT treatment of anxiety and depression (2008–2013). Preliminary evidence suggests that theoretically based transdiagnostic CBT approaches lead to large treatment effects on the primary anxiety disorder, considerable reduction of diagnostic comorbidity, and some preliminary effects regarding the impact on the putative, shared psychological mechanisms. However, the empirical literature remains tentative owing to relatively small samples, limited direct comparisons with disorder-specific CBT protocols, and the relative absence of the study of disorder-specific compared with shared mechanisms of action in treatment. We conclude with a treatment conceptualization of the new transdiagnostic interventions as complementary, rather than contradictory, to disorder-specific CBT.

Recently, the clarification of associations and distinctions between the anxiety disorders has become increasingly focused on 2 fundamental issues: what are the shared, overlapping features of each condition, and what are the unique features that differentiate each condition from another within the anxiety spectrum? Changes in the most current edition of the DSM (DSM-5)¹ reflect this conceptual challenge, with increasing attention toward specification of certain conditions; for instance, OCD and PTSD depart the anxiety disorders group to constitute their own diagnostic boundaries.¹ Despite this increasing diagnostic specification, comorbidity between the anxiety disorders and (major) depression is substantial,² making it the rule rather than the exception in clinical settings.^3,4 Comorbidity between the depressive and anxiety disorders is associated with poorer prognosis, greater symptom severity, increased suicidality, and more functional impairment.^5–8 Comorbidity is also associated with a more chronic and persistent course, compared with either disorder alone,^9–11 and with poorer treatment response, higher relapse and recurrence rates, and greater service use, compared with anxiety disorders alone.⁴

The classic CBT approach has been to develop disorder-specific, manualized treatment protocols that target the symptoms and the putative cognitive, behavioural, and emotional vulnerabilities related to the development and maintenance of each disorder. This approach has supported the diagnostic specificity framework and reflects Beck’s cognitive-content specificity hypothesis that each form of psychopathology has a distinct cognitive profile.¹² However, there are newer manual-based transdiagnostic approaches that attempt to target the shared mechanisms underlying the development and maintenance of anxiety and mood disorders. This approach has been framed to address diagnostic comorbidity and shared mechanisms of vulnerability. Our review aims to provide an update on the changing empirical landscape of CBT. We finish with a discussion around dissemination, training, and future directions for programmatic science in this expanding CBT umbrella.

Classic Cognitive-Behavioural Therapy Approach: Targeting Unique Features of the Anxiety Disorders

Cognitive-behavioural theory and treatment, first introduced in the cognitive-behavioural modelling and treatment of depression and extended to all of the anxiety disorders, has evolved along a coherent scientific framework to include the following: definition and psychometric operationalization of key disorder-specific cognitive, emotional, and behavioural constructs; laboratory investigation of operationalized disorder-specific processes; development of comprehensive CBT interventions to target the processes of empirically tested, disorder-specific models; testing of disorder-specific manuals in RCTs; and finally, examination of disorder-specific moderators and mediators of change in CBT treatment. In keeping with this framework, each of the empirically supported CBT treatment manuals for the DSM anxiety disorders is based on a disorder-specific formulation and includes specific targets for cognitive and behavioural features hypothesized to contribute to the maintenance of the specific condition.

Clinical Implications

• There is substantial empirical support for the CBT treatment of specific anxiety disorders, although there is comparatively less research testing the impact of anxiety and depression comorbidity on outcomes to CBT.

• There is preliminary evidence for the efficacy of brief, group-based transdiagnostic CBT protocols that aim to treat symptomatic comorbidity and shared vulnerability factors.

• Research is required to test transdiagnostic, compared with disorder-specific, CBT protocols regarding impact on comorbidity, mechanisms of change, and attenuating relapse and recurrence of anxiety and mood disorders.

Limitation

• The conclusions regarding the transdiagnostic approaches to anxiety and mood disorders are based on a relatively small set of studies, with small samples that are not representative of the full breadth of anxiety and mood comorbidities. In particular, it remains unclear as to whether transdiagnostic protocols are appropriate for patients with OCD and (or) PTSD.

For example, cognitive-behavioural models of SAD assert that, when people enter social situations, underlying dysfunctional assumptions and beliefs are activated that result in exaggerated perceived social danger.^13,14 This perception of danger or threat activates autonomic arousal, leading to the production of anxiety symptoms that then become the focus of the person during interactions. This makes the person more aware of, and in tune with, interoceptive information, which is then used in the construction of a negatively appraised self-image of how they think they appear to others, contributing to their anxiety in social situations (that is, “If I feel awkward then I must be coming across awkwardly”). After a social event, people with SAD also engage in a postmortem analysis of their social interactions, known as PEP, which is thought to maintain social anxiety through attention and repetitive processing of negative social information.¹³ Experimental studies have provided strong empirical support for this highly idiosyncratic model of SAD, with patients with SAD reporting more negative evaluative thoughts,¹⁵ self-focused attention,¹⁶ negative images,¹⁷ and PEP.^18–20 Further, CBT treatments that have been developed to target these disorder-specific cognitive and behavioural vulnerabilities have been shown to produce exceedingly large treatment effects (for example, d = 2.63).²¹ Evidence also suggests that CBT works, in part, through targeting these disorder-specific cognitive variables: treatment mediation studies show that reductions in probability and cost biases account for fear reductions during treatment,²² and changes in cognitions about loss of control mediate treatment outcome of exposure therapy.²³

During the past 3 decades, significant research support has accrued from RCTs for the efficacy of CBT in the treatment of all DSM anxiety disorders.^24–28 Based on meta-analytic reviews, the treatment effects for disorder-specific, manualized CBT treatments are extremely large, with pre–post effect sizes in the range of d = 1.97 for PD/A, d = 2.03 for OCD, d = 2.02 for GAD, d = 1.74 for PTSD, and d = 1.16 for SAD, with an overall average d of 1.56.²⁸ Additional meta-analyses demonstrate that structured, short-term CBT treatments for the anxiety disorders translate well into interventions in the community, with substantial effectiveness data from application in real-life clinical contexts.²⁹ Collectively, these findings have led to the recognition of CBT as an empirically supported therapy and to its inclusion in prominent treatment guidelines^30–37 for the spectrum of anxiety disorders.

While there is substantial empirical support for the CBT treatment of specific anxiety disorders, there is comparatively less research directly testing whether the treatment of anxiety disorders is adversely affected by the presence of anxiety and depression comorbidity, or investigating the extent to which the successful treatment of one anxiety disorder produces secondary treatment effects on other conditions within the mood and anxiety spectrum. Recently, our team conducted an empirical review of the extant literature to determine whether the CBT treatment of primary anxiety disorders is moderated (that is, attenuated) by the presence of comorbid depression, and the extent to which treatment produces secondary effects on depression symptoms.^3,4 Generally, the findings appear to differ based on the primary anxiety disorder under consideration and the degree of depression severity. Depression does not typically moderate either the effect of CBT for PD (with or without agoraphobia) or, when depression is in the mild-to-moderate range, the response to CBT for OCD. However, diagnostic threshold depression does moderate outcomes in the exposure and response prevention treatment of OCD. Further, there is considerable support to suggest that diagnostic threshold depression moderates the effects of CBT in GAD and SAD. There is comparatively less research investigating the impact of depression on treatment response for PTSD.³ In gauging the impact of CBT on comorbid depressive symptoms when the anxiety disorder is the principal target, our review demonstrated that there is typically significant reduction of comorbid depressive symptoms but not necessarily to the point of full remission. This parallels a meta-analytic investigation of the effects of CBT on comorbid depression in the treatment of primary anxiety disorders²⁹ that demonstrated impressive moderate-to-large treatment effects, but still less than what is commonly observed when depression is directly targeted with CBT.³⁸

Based on these empirical findings, the recent Canadian Network for Mood and Anxiety Treatments task force recommendations for the management of patients with mood and anxiety comorbidity concluded that for depression in the severe range and (or) that meets the diagnostic threshold, one should consider first treating the depression with disorder-specific CBT manuals to enhance engagement, increase tolerability of exposure-based approaches, improve motivation, and, consequently, the successful completion of between-session homework. The anxiety disorder should then be treated in the second instance within evidence-based, disorder-specific manuals for the appropriate anxiety disorder. For mild-to-moderate and (or) diagnostically subthreshold depression, the recommendation is to proceed with the CBT treatment of the primary anxiety disorder with relatively minimal adjustment to the standard protocols. Following successful treatment of the anxiety disorder, the aim should be to directly treat the secondary depressive episode or reduce residual symptoms of depression to the status of remission to diminish relapse and recurrence risk.⁴

While the empirical literature currently appears to justify these treatment guidelines, the literature is sparse as to how CBT clinicians should determine the particular sequence of treatments for multiple mood and anxiety disorders; attempt to limit comorbid disorders from interfering in treatment of primary disorders; deliver treatment protocols to maximize impact on a range of present conditions; and ensure that various disorders are treated through to remission. From this, numerous key questions appear to be unresolved in the CBT literature, including where clinicians should begin in the face of multiple clinical conditions, and what adjustments to standard protocols may be required to maximize clinical outcomes. For these reasons and others, the disorder-specific approach has not remained uncontested. However, there has been a growing interest in transdiagnostic treatment approaches as potential solutions to the perceived challenges associated with the classic CBT approach, reflecting the emerging empirical evidence for common psychological mechanisms underlying anxiety and depression.

Higher-Order Factors Shared Across Disorders

The extent of diagnostic comorbidity between the anxiety and mood disorders, as well as the overlap in dimensional symptom ratings, has led to new structural models of the mood and anxiety disorders, which postulate that each disorder has a shared component that can account for comorbidity and its own unique component that distinguishes it from others. During the past decade, considerable empirical evidence has been generated for hierarchical structures of mental disorders^39–42 that demarcate into higher-order dimensions of internalizing disorders, including the mood and anxiety disorders, and externalizing disorders, including conduct and antisocial disorders, and substance use disorders. Recent advances in research on personality structure have similarly focused on an empirically based, quantitative, hierarchical structure, with broader traits occupying higher levels of the hierarchy, and subsumed narrowly defined traits at lower levels. Structural models of personality, such as the tripartite model^43,44 and the five-factor model of personality⁴⁵ provide a common and comprehensive taxonomy for comparing and contrasting a multiplicity of traits at different levels within a single hierarchical structure.⁴⁶ The tripartite model⁴³ draws heavily on psychiatric comorbidity surveys and structural analyses of genotypic and phenotypic datasets^39,47–50 to postulate that common, genetically determined personality traits underlie DSM mood and anxiety disorders.

Initially, Watson et al⁵¹ proposed that depression and anxiety disorders share a common component, negative affectivity, whereas positive affectivity was a feature specific to depression. Numerous studies have demonstrated that these 2 dimensions are differentially related to depression and anxiety, with negative affectivity constituting a nonspecific factor common to mood and anxiety disorders, and low positive affectivity being differentially associated with depression.^40,52 Similarly, there is considerable evidence demonstrating high levels of neuroticism to be associated with all of the mood and anxiety disorders (excluding simple phobia) in community samples.^53–57 Moreover, there is support for the role of low extraversion in depression, although in contrast to the hypothesized specificity of low positive affectivity and depression; low extraversion also appears to be associated with the anxiety disorders^53–55 and social phobia in particular.^54,57–63 In summary, structural models of affect and personality see the broad personality traits of negative affectivity and (or) neuroticism as being closely linked to all of the mood and anxiety disorders, and accounting largely for their comorbidity. As such, there is growing support for the commonalities among the mood and anxiety disorders through high rates of diagnostic comorbidity, substantial overlap in dimensional symptom ratings, and the extensive evidence that the mood and anxiety disorders share a common set of psychological vulnerability factors. This has provided the impetus to the development of new CBT treatments that focus on psychological processes and treatment strategies that cut across the mood and anxiety disorders, referred to as transdiagnostic treatments.

New Transdiagnostic Approaches

Unified Protocol

The UP⁶⁴ in the treatment of the emotional disorders is a new manual-based CBT intervention that has been designed to target all anxiety disorders and MDD by treating common underlying factors, instead of addressing disorder-specific symptoms. Specifically, the UP has been designed to address the tendencies to experience negative emotions (for example, heightened neuroticism) and to interpret such emotional experiences as harmful. The treatment is comprised of 8 modules, targeting the following:

1. motivational enhancement;

2. psychoeducation and understanding emotions;

3. emotional awareness training;

4. cognitive reappraisal;

5. attenuation of emotional and behavioural avoidance;

6. awareness and tolerance of physical sensations;

7. interoceptive and situational exposure; and finally,

8. relapse prevention.⁶⁴

Preliminary evidence has begun to emerge in support of the efficacy of the unified protocol.^65,66 Ellard et al⁶⁶ clinically tested the efficacy of the UP in 2 open clinical trials of patients with a principal diagnosis of an anxiety disorder. Preliminary findings across both studies of very limited sample size suggest that the UP was associated with significant treatment effects, as evidenced by high rates of responder status and high end-state functioning. There was evidence of remission not only for the primary disorder but also for comorbid conditions. In the second study, these benefits were maintained and grew further during a 6-month follow-up period. While encouraging, these findings remain preliminary and lack a comparison control group.

Recent examinations have included comparisons of the UP with wait-list control subjects in samples of patients with a principal diagnosis of an anxiety disorder. A recent RCT examined the efficacy of the UP (n = 26) as compared to a wait-list control (n = 11) within a diagnostically heterogeneous group of patients with a primary anxiety disorder and secondary anxiety or mood disorder.⁶⁷ Consistent with preliminary evidence, subjects in the treatment condition exhibited improvement in symptom severity, levels of negative and positive affect, and overall functioning, compared with the wait list control subjects. At posttreatment, more than 50% of participants in the UP treatment condition no longer met diagnostic criteria for their primary diagnosis, with 45% of this subset not meeting criteria for any diagnosis. For participants with a comorbid mood disorder, 67% achieved responder status, indicating the potential for the UP to treat depression alongside anxiety. Within the same dataset, the contributions of negative affectivity and negative reactivity to emotions in predicting outcomes for the UP were examined.⁶⁸ Following the UP, large decreases were seen both in the frequency of negative emotions and in emotional reactivity, or, more specifically in line with the goals of the UP, acceptance and awareness of emotions increased, while fear of emotions and anxiety sensitivity decreased. Both the change in frequency of negative emotions and reactivity to their occurrence were significantly associated with change in clinician-rated anxiety, depression, and severity of principal diagnoses.

Finally, there have been recent attempts to tailor the UP to address younger populations. In an open clinical trial, Bilek and Ehrenreich-May⁶⁹ tested the feasibility and preliminary outcomes of a UP treatment of anxiety and depression comorbidity for youth. At posttreatment, significant and large improvements were observed in clinician-rated measures of anxiety (d = 1.38), the sum of anxiety and depressive disorder severity ratings (d = 1.07), child-reported anxiety (d = 0.47), and parent-reported depressive symptoms (d = 0.54). Transdiagnostic treatment was also found to have high retention rates and reports of satisfaction among school-aged children, providing preliminary evidence of the feasibility and efficacy of transdiagnostic CBT protocols for youth anxiety disorders with comorbid depression.

Transdiagnostic Cognitive-Behavioural Therapy Protocols

A second development in transdiagnostic treatment protocols is the development of a 12-session, manual-based group CBT protocol⁷⁰ for patients with co-occurring anxiety and depression. Similar to the UP approach, the transdiagnostic approach eschews diagnostic distinctions and instead focuses on common elements developed in disorder-specific CBT pertaining to psychoeducation and self-monitoring, cognitive restructuring, and exposure to feared stimuli. The final stages of the treatment focus on cognitive therapy strategies for nondisorder-specific anxiety beliefs pertaining to perceptions of uncontrollability, unpredictability, and threat. Recent empirical studies have demonstrated promise for this new approach. An RCT by Norton⁷¹ examined the efficacy of a 12-week transdiagnostic CBT group treatment, compared with a 12-week comprehensive RLX. It was found that transdiagnostic CBT and RLX showed statistically equivalent and significant treatment efficacy. Further, the effect size estimate for transdiagnostic CBT from session-by-session, self-report measures (d = 1.43) was somewhat comparable to average effects from diagnosis-specific CBT protocols (d = 1.58),⁷² and no difference in efficacy was seen between primary diagnoses (PD, SAD, and GAD).

Transdiagnostic CBT has also been directly compared to disorder-specific CBT protocols in a small-scale RCT of 12-week protocols for PD, SAD, and GAD (n = 46; 58.7%, with a comorbid diagnosis including MDD).⁷³ Results showed significant improvement for both disorder-specific and transdiagnostic protocols during treatment, with equivalence in effects across conditions and no differences in treatment credibility. However, pre–post means and effect sizes of the interventions were not reported, thus it was not possible to determine whether the interventions produced small, medium, or large equivalent effects. More recently, Norton et al⁷⁴ examined the effectiveness of a 12-week transdiagnostic CBT group treatment for anxiety in reducing comorbid diagnoses (n = 79). Data from 3 previous trials were used to compare treatment effects between patients, with and without comorbid diagnoses (most commonly depression, followed by other anxiety spectrum disorders). About two-thirds of patients with comorbid diagnoses at pretreatment no longer met criteria for a clinically severe comorbid diagnosis at posttreatment.

Other similar transdiagnostic CBT approaches for the anxiety disorders, but with different protocols, have also received empirical support. A transdiagnostic approach to anxiety and depression comorbidity was tested by randomly assigning patients with a primary anxiety disorder (n = 152; 43% with a comorbid diagnosis, and 30% meeting criteria for MDD) to 11 weeks of transdiagnostic CBT group or a wait-list control group.⁷⁵ The treatment group reported significantly greater reductions in anxiety than the wait-list group at posttreatment, with gains maintained at 6-month follow-up, and with treatment effects in the moderate range.

Another protocol using key elements of transdiagnostic CBT, but with a focus on targeting safety behaviours across anxiety disorders, has also been examined.⁷⁶ Patients with a primary anxiety disorder diagnosis of GAD, PD, or SAD (n = 96; 39.1% comorbid MDD) were randomly assigned either to 10-weeks of transdiagnostic CBT or to a wait-list control group. Significantly more participants in the CBT condition demonstrated clinically significant improvement than control subjects at posttreatment, with gains maintained at 3-month follow-up, as well as on clinician-rated severity of symptoms, but again only medium treatment effects were evinced.

Finally, recent work has attempted to demonstrate the feasibility and efficacy of transdiagnostic approaches for older adults. A recent RCT tested the effectiveness of transdiagnostic CBT in a population of older adults (more than 60 years) with a DSM-IV diagnosis of comorbid anxiety and depression (n = 62), whom were randomly assigned to either 12 weeks of group CBT or a wait-list condition.⁷⁷ Compared with the wait-list condition, group CBT resulted in significantly greater reductions on symptoms of anxiety and depression, measured by both self-report and diagnostic interviews, with an overall medium effect size (d > 0.4). Interestingly, no differences were found when the effects of the CBT program on anxiety and depression symptoms were assessed separately, indicating that the program did not differ statistically in its efficacy in reducing primary anxiety and primary mood problems.

Cognitive-Behavioural Therapy Experts: Disorder-Specific, Transdiagnostic, or Combined Approach?

Given the solid rationale for developing transdiagnostic protocols in tandem with demonstrated emerging empirical support, we thought it would be informative to survey expert CBT clinicians to directly assess their typical assessment and treatment approach to anxiety disorders in the presence of comorbid depression.⁷⁸ Specifically, we investigated whether expert CBT clinicians focus on treating disorders within disorder-specific manuals with sequential delivery or whether they target shared symptoms and underlying vulnerabilities when presented with anxiety and depression comorbidity. Participants were recruited to form an expert CBT panel based on membership in the Association for the Advancement of Behavioral and Cognitive Therapies and the presence of internationally recognized significant contributions to the treatment of anxiety, mood, or their comorbidity. About two-thirds of respondents reported that they would treat the disorders sequentially or usually sequentially, while one-third of respondents indicated that they would focus on both shared features and (or) underlying vulnerabilities and also take a sequential approach to treatment. In total, about three-quarters of respondents reported usually using some type of sequential treatment approach.⁷⁸ These findings suggest that, currently, CBT experts report retaining a disorder-specific approach, although a significant number of respondents also included some degree of attention to transdiagnostic features.

These results also reflect current international guidelines for the development of CBT competence. The Improving Access to Psychological Therapies program in the United Kingdom suggests that the ability to formulate and treat anxiety and (or) depression comorbidity is at the highest level of CBT therapist competence.⁷⁹ According to this model, the competences required to effectively deliver CBT fall into 5 domains:

1. generic competences;

2. basic cognitive and behavioural therapy competences;

3. specific cognitive and behavioural therapy techniques;

4. problem-specific competences; and

5. meta-competences.

The second-highest level, problem-specific competences, includes knowledge of the cognitive-behavioural techniques used to treat specific psychological disorders, as outlined in empirically supported treatment manuals.^79,80 At the highest level, meta-competences would include the management of obstacles in treatment that emerge around a complex comorbidity that is not specifically addressed in treatment manuals, or at least require adjustments to the manuals.⁸¹ As such, the basis for current CBT training flows from developing disorder-specific expertise but with the ability to apply flexible, sequential approaches in the context of comorbidity. This model is largely reflected in how CBT experts currently assess and treat mood and anxiety comorbidity.

Summary and Conclusions

There are well-established grounds for proposing transdiagnostic approaches to treat the overlapping symptoms and psychological processes of anxiety disorders and MDD. Recently, numerous RCTs have demonstrated the potential efficacy of the transdiagnostic approach for primary and comorbid anxiety and for mood disorders. There has also been very preliminary research demonstrating the relation between symptomatic improvements, and the extent to which shared mechanisms are successfully targeted and reduced.⁶⁸ However, this extant empirical literature is still small, and most studies have used underpowered RCT designs to test treatment efficacy and differential mechanisms. There has also been a dearth of direct comparisons with disorder-specific CBT protocols, and thus it remains unclear as to whether these protocols match or exceed standard CBT protocols. Finally, studies have not addressed the extent to which clinical outcomes in transdiagnostic protocols occur due to the well-established, disorder-specific approaches that have been culled from existing manuals, or as a result of the new elements that target the shared features (for example, emotional reactivity in UP, or uncontrollability and predictability in the transdiagnostic anxiety approach). There also appear to be some attenuation of treatment effects as protocols move away from theoretically derived transdiagnostic approaches (that is, UP, and [or] Norton’s Transdiagnostic Approach), with treatment effects occurring only in the moderate range and well short of the very large treatment effects commonly observed in disorder-specific CBT.⁷² Moreover, the emphasis in the development of these protocols was the putative advantages offered in reducing diagnostic comorbidity. However, to date, no study has demonstrated empirical advantage to the transdiagnostic approaches, compared with disorder-specific CBT, in reducing mood and anxiety comorbidity, although studies reviewed demonstrate the promise of the transdiagnostic approach to reduce anxiety and depression comorbidity. Finally, it has been previously suggested that transdiagnostic CBT may not be as effective with patients with OCD and (or) PTSD.^82,83 Studies have included either no OCD or PTSD samples^69,73,76 or only a few.^71,74,77 This parallels the DSM-5, and structural models of symptom and personality ratings^55,84 that locate OCD and PTSD outside the anxiety disorder umbrella. Future research will require clarifications as to whether these patients are suitable for the transdiagnostic approach.

Notwithstanding these limitations, the potential advantages of these new approaches include the extent to which evidence-based CBT—in the presence of a single, manualized protocol that can be effective for a wide range of anxiety disorders and depression—could be efficient, cost-effective, and improve access and availability, particularly in geographic locations where resources are limited. Transdiagnostic approaches, with the easy-to-engage group CBT format, may represent a more tolerable starting point, particularly for patients with significant anxiety and mood comorbidity, which could then be followed by high-intensity, disorder-specific interventions. Alternatively, treatment pathways to evidence-based CBT could follow from narrow to broad, with disorder-specific protocols being delivered for the primary Axis I anxiety disorder, followed by transdiagnostic approaches targeting remaining comorbid symptoms and transdiagnostic vulnerabilities (again particularly for patients with high comorbidity). This sequencing framework, as illustrated in Figure 1, will undoubtedly require scientific examination. Importantly, progress within this expanding umbrella of CBT treatments for the anxiety disorders will be best achieved by conceptualizing these newer transdiagnostic approaches as complementary rather than contradictory to the well-established, empirically-supported, disorder-specific CBT approach.

Figure 1.

Hierarchical structure of the specificity of factors contributing to anxiety, and corresponding interventions

Abbreviations

CBT

cognitive-behavioural therapy

DSM

Diagnostic and Statistical Manual of Mental Disorders

GAD

generalized anxiety disorder

MDD

major depressive disorder

OCD

obsessive–compulsive disorder

PD

panic disorder

PD/A

PD with agoraphobia

PEP

post–event processing

PTSD

posttraumatic stress disorder

RCT

randomized controlled trial

RLX

relaxation training program

SAD

social anxiety disorder

UP

unified protocol