DBT for Comorbid Depression and Anxiety: Treatment Effectiveness

Introduction: Comorbid Depression and Anxiety

Depression and anxiety are two of the most common mental health problems in the United States. These two conditions affect a significant percentage of the population, meaning that billions of dollars are spent every year caring for these conditions and their related complications. Additionally, depression and anxiety are associated with significant declines in patient social functioning and well-being. Both disorders have also been found to cause great suffering to patients and their close friends and family. Despite the existence of proven treatments, both conditions remain undertreated (Rizvi, 2011). The diagnosis and subsequent treatment of these disorders are made even more difficult by the fact that they share many signs and symptoms. Data from the National Comorbidity Survey shows that at least 58% of individuals with lifetime depression have a minimum of one anxiety disorder. Patients with comorbid anxiety and depression were also found to have significantly lower levels of productivity and higher use of healthcare resources (Ballenger, 2000).

Depression and anxiety have been found to frequently co-occur, both sequentially and concurrently, in both children and adults. The presence of one disorder has also been found to increase the risk of developing the other over time. The most prevalent anxiety disorder among adults is Generalized Anxiety Disorder (GAD), while the most prevalent depressive disorder is Major Depressive Disorder (MDD). GAD and MDD frequently appear together in many patients and have been shown to run through family lines (Garber & Weersing, 2010).

One of the most frequently used forms of psychotherapy today is Cognitive Behavioral Therapy (CBT). CBT helps individuals understand their thought processes so that they can change how they feel and behave. The majority of American psychotherapists who practice CBT use a version of it that is more goal-oriented and time-limited (Garber & Weersing, 2010). A version of CBT that is gaining prominence among therapists is Dialectical Behavior Therapy (DBT). DBT is based on the principles of CBT, which it uses to increase treatment effectiveness and to focus on specific issues. The founder of DBT, Marsha Linehan, developed this approach after identifying deficits in standard Cognitive Behavioral Therapy (Matusiewicz, Hopwood, Banducci, & Lejuez, 2010). This study therefore aims to support the understanding and delivery of best practices in psychological therapy.

Psychiatrists have long recognized the relationship between anxiety and depression, though detailed research into the phenomenon is still in relatively early stages. According to various studies, both conditions are known to occur together more often than as singular clinical illnesses. Many researchers believe that one or both conditions can emerge when a prolonged illness has persisted — for example, chronic anxiety can transform into depression over time. In short, anxiety may be considered a prodrome for depression. The co-presence of both conditions in a single patient can greatly worsen clinical outcomes, as the combination may slow the effectiveness of medication and clinical treatment. Newer antidepressants, however, are increasingly effective at targeting both mood and anxiety symptoms.

Diagnostic Challenges and Clinical Presentation

The prevalence of comorbid depression and anxiety as a combined presentation in a single individual is difficult to monitor due to numerous diagnostic overlaps. Available data suggests that as many as 10% of patients in primary care settings exhibit comorbid anxiety and depression. However, almost 60% of MDD patients also exhibit moderate levels of anxiety (20–25%), while the remainder exhibit severe anxiety, and there is no fixed diagnostic criterion that covers this combination (Ballenger, 2000).

In primary care settings, it is particularly difficult to diagnose patients with comorbid anxiety and depression because they do not fall neatly within specific criteria for either condition. This presentation has therefore been named "Mixed Anxiety-Depressive Disorder." To better establish a diagnostic basis for such patients, the American Psychiatric Association (APA) integrated the condition into the DSM-IV under a provisional category. The symptoms of this disorder are incomplete or low-intensity forms of both anxiety and depression. This disorder is typically characterized by the following symptoms:

• Difficulty in concentration
• Memory loss
• Lack of sleep
• Recurring dysphoric moods
• Fatigue
• Irritability
• Low energy and a tendency toward worrying

While these symptoms are congruent with both anxiety and depression, the evidence from any single symptom cluster is usually insufficient for a full diagnosis of either disorder. Even when both conditions coexist, one tends to be more dominant than the other. For example, if the coexisting depression is dominant, the patient will show hopelessness and an absence of positive affect, while dominant anxiety is more likely to manifest as motor tension and/or hyperactivity (Ballenger, 2000).

Even when diagnosis is not straightforward, the treatment process should begin with managing the patient's anxiety symptoms. Once one aspect is managed, the other can be addressed with a regimen of antidepressants. A combination of medication and therapy is generally required for full remission of depression. One pharmacological combination that is frequently recommended for comorbid anxiety and depression is benzodiazepines (BZD) or buspirone combined with an antidepressant. Because traditional anxiolytics have little to no effect on depression, coupling them with antidepressants is essential for managing this disorder (Koons et al., 2001). Clinicians must, however, exercise care in tapering such medications gradually, as withdrawal effects — particularly from drugs like BZD — can be significant.

Method: Literature Search and Data Collection

Data Sources

The purpose of this review is to evaluate the evidence for the efficacy of various psychological interventions used in the treatment or management of comorbid anxiety and depression. Three databases were used in conducting this literature review: MEDLINE (a database of the United States National Library of Medicine); PsycINFO (a database of psychology articles, reports, and related literature maintained by the APA); and the Cochrane Library (an evidence-based database for healthcare literature).

The search was restricted to literature published between 2011 and 2014. Given constraints of time and resources, only literature published in English was considered; previous reviews indicate that this kind of restriction has little impact on overall outcomes. The search was also restricted by age, with only adult populations considered. Further restrictions were applied based on study design, intervention settings, and outcome evaluation methods. Only empirical studies were included in the final selection (Valentine et al., 2015). The drawbacks of the systematic review approach identified in this paper include: a long time scale, a narrow focus, lack of cost-effectiveness analysis, a wasteful approach to data retrieval, and limited clinical relevance (Leitner et al., 2006).

Sample and Search Strategy

The following keywords were used in searches across the three databases: "depress*," "depression," "dysthymic disorder," "depressive disorder," "intent*," "Depression and anxiety," "DBT compared with CBT," "DBT Effectiveness," and "Success." (The asterisk indicates a wildcard search, which retrieves all records containing the phrase preceding the asterisk.) After removing duplicates and applying the restriction criteria described above, thirty-six individual texts were identified. Applying the intervention restriction criteria further reduced this number to eighteen texts. Random sampling of the excluded texts revealed that the majority were purely discursive and that many focused on risk rather than intervention (Farrell, Shaw, & Webber, 2009).

The abstracts of the remaining texts were individually reviewed to exclude those that did not meet the review criteria. Ambiguous texts or those lacking sufficient information were reviewed by additional readers. At the conclusion of this process, twelve papers out of the initial thirty-six were deemed sufficiently relevant for full-text review. Each was read in full before a final decision was made to include all twelve in the review (Valentine et al., 2015; Kvarstein et al., 2015).

Summary of Collected Data

The review identified a range of methodological problems relevant to the current research evidence that must be addressed if future research is to support evidence-based practice. The review also identified limitations in the scope and focus of the existing evidence base. Due to what might be described as a "scatter-gun" approach to the study and treatment of comorbid anxiety and depression, neither clinicians nor policymakers have been able to benefit fully from a poor evidence base consisting largely of small studies addressing a much larger issue (Campbell, 2000). The patients most affected by this gap are those with comorbid anxiety and depression across the full age spectrum, including cultural and ethnic minorities and individuals of varying socioeconomic status, groups that the literature has tended to overlook.

On the whole, the quality of the available research compares favorably to other larger studies examining anxiety and depression separately (Leitner et al., 2006). This relative favorability does not, however, mask significant methodological failings — many of which stem from ethical and practical restrictions on research involving suicidal behavior. For example, researchers have not been able to randomize participants, set standard treatment conditions, conduct blinded investigations, or control for outside stimuli. Participant dropout rates are also frequently high, complicating accurate analysis.

While much of the database material originates in the United States or Canada, the literature has an international focus, with contributions from 21 countries. The United Kingdom is notably active in this field, accounting for approximately 19% of empirical studies, though only five independent UK studies specifically address comorbid anxiety and depression, drawn from Scottish population data (Leitner et al., 2006).

A prominent trend in the literature is the association of comorbid anxiety and depression with mental illness more broadly. Nearly half (46%) of existing research focuses on interventions for a psychiatric population, particularly patients with depression and/or borderline personality disorder. While mental illness is indeed a significant risk factor, it is not a prerequisite for comorbid presentations, and this association represents an overgeneralization. The existing research also largely neglects community settings such as schools, colleges, and prisons, and emergency situations remain poorly studied (Chapman, 2006).

Data Analysis Approach

The data analysis approach utilized for this review was inductive. This approach better meets the rational and practical needs of clinical research by allowing iterative exploration of outcomes and following the empirical approaches used in primary research. An added benefit of inductive analysis for psychological research is that it allows thematic grouping of texts to be data-driven rather than imposed by a predetermined framework. This approach also enables analysis across different study designs and evaluates not only outcomes but also participant characteristics as variables, providing the flexibility required to address clinical issues in complex studies (Matusiewicz et al., 2010; Rizvi, 2011).

Findings: DBT Implementation and Treatment Outcomes

Content analysis was clustered based on the results and descriptions provided in the published literature. Data from all included studies was analyzed at least three times and reviewed against other studies containing similar variables or results. Where discrepancies were found, they were resolved through careful repeated reading and discussion of the relevant literature. Initially, data were gathered regarding the characteristics of populations receiving DBT (sex, race, and gender), along with comparisons between samples and other studies with similar demographics and implementation methods. All outcome measures and follow-up results were also captured. A second pass collected comparative data related to CBT as a treatment modality. Risk of bias was assessed using PRISMA standards (Liberati et al., 2009; Matusiewicz et al., 2010).

Thematic Area 1: DBT Implementation

Dialectical Behavior Therapy (DBT) is a comprehensive intervention initially developed for the management of suicidal behavior and borderline personality disorder (BPD). As a treatment system, DBT integrates behavioral therapy approaches designed to promote change with validation strategies focused on acceptance. These elements are delivered through weekly outpatient group skills training and individual psychotherapy sessions. Four core behavioral skills are both taught and reinforced through therapy:

• Mindfulness
• Emotion regulation
• Interpersonal effectiveness
• Distress tolerance (Matusiewicz et al., 2010)

Mindfulness is considered a pivotal skill in DBT because it is integrated into all other skill modules and is regarded as a central component of effective treatment. Since there is no single standardized method for conducting inpatient DBT, the treatment packages described in the reviewed studies varied considerably. However, a standard framework for outpatient DBT exists, and many authors reported working within it. Researchers Lynch, Trost, Salsman, and Linehan (2007) provide information about treatment stages but do not elaborate on the specific treatment strategies used. Most treatment periods in the reviewed studies ranged from two weeks to three months.

In DBT, several interventions and skills are oriented toward cultivating acceptance — both of the patient by the clinician and of the patient's self, others, and the world. Mindfulness exercises require active participation: attending to and remaining non-judgmental toward the full range of experience, describing the facts of a situation while maintaining present-moment awareness (Koons et al., 2001). A key goal of these exercises is to build skills and reinforce adaptive behavior.

Another acceptance-oriented technique within the distress tolerance module is "Radical Acceptance." This exercise invites patients to confront their current reality and accept it without struggle or willful resistance — not through the filter of their personal preferences, but as an honest acknowledgment of their feelings, events, and emotions. The skill of the clinician lies in guiding patients toward greater acceptance and acceptance-oriented responses (Ballenger, 2000).

Standard outpatient DBT includes weekly individual therapy sessions of approximately one hour. Of the eight studies that described their treatment strategies, only one did not include individual therapy (Valentine et al., 2015). Dialectical philosophy — most frequently associated with Hegel or Marx — forms the conceptual backbone of DBT's distinctiveness from other cognitive-behavioral therapies. Within a dialectical framework, reality consists of opposing forces in tension. For instance, the push to use change-oriented strategies creates tension by amplifying the patient's desire to be accepted rather than changed. The therapist must constantly balance these forces (Ballenger, 2000). Focusing exclusively on change-oriented strategies is an incomplete approach, as it lacks acceptance — a particular concern when working with suicidal individuals.

Dialectical thinking shapes many facets of a therapist's style. The therapist integrates both change and acceptance strategies to maintain therapeutic balance, working toward a framework in which validation of the patient's experience and acceptance of their situation become possible. When proposing resolutions, the therapist typically offers both acceptance-centered approaches (e.g., tolerating pain, radical recognition, mindful awareness of events and emotions) and change-centered approaches (e.g., modifying behaviors, solving problems, altering environments, changing cognitions). The dialectical mode allows the therapist to move away from being "right" and toward synthesizing their perspective with the patient's (Chapman, 2006). Additionally, DBT sessions are characterized by movement, natural flow, and variation in pace and intensity, which the therapist uses to maintain the dialectical balance.

Standard outpatient group skills training occurred approximately 2.5 hours per week across all reviewed studies. Sessions covered interpersonal effectiveness, emotional regulation, distress tolerance, and mindfulness. All studies included some form of skills training activity. In standard DBT, therapists also engage clients by phone to help them develop the ability to seek support between sessions; however, none of the reviewed articles described telephone consultations taking place (Valentine et al., 2015). Regarding therapist consultation groups, standard outpatient DBT includes weekly consultation meetings; six of the studies incorporated once- or twice-weekly meetings in their treatment plans. Of the twelve included studies, nine conducted comparison analyses between a group receiving DBT and a group receiving either CBT or another depression/anxiety intervention.

Thematic Area 2: Treatment Outcomes

Across all twelve studies, groups receiving DBT treatment reported improvements in at least one symptom or problematic behavior, with some individuals reporting changes across multiple areas. Of the eight studies that examined depressive symptoms, six reported a considerable reduction after DBT treatment, with many behavioral improvements maintained for up to 21 months post-discharge. One study reported a reduction in depressive symptoms that was not substantially greater than the reduction observed in the CBT comparison group. Three studies investigated anxiety symptoms; in two of these, symptoms were reduced and improvements maintained for more than one month (Valentine et al., 2015; Kvarstein et al., 2015).

Thematic Area 3: Cost-Effectiveness Data

After adjusting for initial depression severity, age, and the presence or absence of chronic disease, the cost-effectiveness of DBT intervention was reported at more than 50 depression-free days within the first six months, compared to groups receiving other psychotherapy interventions. This improved outcome was achieved at an additional cost of $36.70 above standard care alone. These findings suggest that DBT is more effective — and marginally more costly — than standard care in the treatment of comorbid anxiety and depression in adults (Garber & Weersing, 2010; Matusiewicz et al., 2010).

References

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