DBT for Comorbid Depression and Anxiety: Clinical Effectiveness

Introduction

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 to care for them and their related complications. Additionally, depression and anxiety are associated with significant declines in patients' social functioning and overall well-being. Both disorders have also been found to cause great suffering and pain to patients as well as to their close friends and family members. 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. For instance, 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 frequently co-occur, both sequentially and concurrently, in both children and adults. It has also been found that the presence of one disorder increases 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 tend to run through family lines (Garber & Weersing, 2010).

One of the most frequently used forms of psychotherapy today is Cognitive Behavioral Therapy (CBT). The focus of this therapy is to help individuals understand their thought processes so that they can eventually change how they feel and behave. The majority of American psychotherapists who practice CBT use a version of it that is 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 extends to increase treatment effectiveness and to address specific issues. The founder of DBT, Dr. Marsha Linehan, developed this approach after identifying deficits in standard Cognitive Behavioral Therapy (Matusiewicz, Hopwood, Banducci & Lejuez, 2010). This study therefore aims to contribute to the understanding and delivery of best practices in psychological therapy.

Method

Data Sources

The purpose of this review is to evaluate evidence of 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 for storing psychology articles, reports, and other literature; and the Cochrane Library, an evidence-based database for healthcare literature.

During the search of each database, only literature published between 2011 and 2014 was considered. Given the limited time and resources available for the review, only literature published in English was included. Previous reviews indicate that this kind of restriction has little impact on overall outcomes. Consistent with the study's specifications, 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. To obtain the most relevant data, these criteria were used to refine the search process, and only empirical studies were considered (Valentine et al., 2015).

Sample Unit Description

In the search of the three databases, the following keywords were used: "depress*" OR "depression" OR "dysthymic disorder" OR "depressive disorder" OR "intent*" OR "Depression and anxiety" OR "DBT compared with CBT" OR "DBT Effectiveness" OR "Success." (The asterisk denotes a wildcard search, retrieving all entries containing any phrase preceded by the specified characters.) After removing duplicate results and applying the restriction criteria described above, thirty-six individual texts were identified. Applying the intervention restriction criteria further reduced this number to 18 texts. Random selection checks on excluded texts revealed that the majority were purely discursive in nature. It was also apparent that there was an imbalance in the literature, with many texts focusing on risk factors rather than interventions (Farrell, Shaw & Webber, 2009).

The abstracts of the remaining texts were each individually reviewed to exclude any that did not meet the review criteria. Those that were ambiguous or lacked sufficient information were reviewed by additional readers. At the end of this process, 12 papers out of the initial 36 were deemed potentially relevant and were obtained in full-text format. Each was read in full, after which a final decision was made to include all of them in the review (Valentine et al., 2015; Kvarstein et al., 2015).

Data Analysis Approach

The data analysis approach used for this review was inductive. This approach was selected because it better meets the rational and practical needs of research on clinical matters. Inductive data analysis allows iterative exploration of outcomes by following the empirical approaches utilized in primary research. An added benefit of this approach for psychological research is that it allows any grouping or clustering of texts around key themes to be data-driven. Additionally, inductive data analysis accommodates data from different types of study designs and evaluates not only outcomes but also participant characteristics as a variable. This approach provides the flexibility required to address clinical issues in complex studies (Matusiewicz et al., 2010; Rizvi, 2011).

Findings

Content analysis was clustered based on the results and descriptions provided in the published literature. Data drawn from each source was analyzed at least three times and reviewed against other studies containing similar variables or results. Where discrepancies were identified, they were resolved through careful and repeated reading of the pertinent literature and discussion of the content. Initially, data were gathered from each paper using the demographic characteristics of the populations receiving DBT (sex, race, and gender), along with comparisons of the sample against studies with similar demographics and descriptions of how the therapy was implemented. All outcome measures and any follow-up results were also recorded. A second step involved collecting data related to CBT as a comparison treatment. To assess risk of bias, different methodological factors were evaluated for each study using PRISMA standards (Liberati et al., 2009; Matusiewicz et al., 2010).

Thematic Area 1: DBT Implementation

Since there is no single standardized method of conducting inpatient DBT, the treatment packages described across the reviewed texts varied considerably. However, a standard framework for outpatient DBT does exist, and many authors reported operating within it. Researchers Lynch, Trost, Salsman, and Linehan (2007) provide information about treatment stages but do not describe in detail the specific treatment strategies used.

Treatment Duration: Most treatment periods ranged from two weeks to three months, which was also the modal period of treatment.

Individual Therapy: Standard outpatient DBT entails weekly individual therapy sessions lasting approximately one hour. Of the eight studies that described their treatment strategies, only one did not include individual therapy (Valentine et al., 2015).

Group Skills Training: Standard outpatient group skills training reported in the studies was approximately 2.5 hours per week. These sessions included training in four main areas: interpersonal effectiveness, emotional regulation, distress tolerance, and mindfulness. All studies incorporated some variation of a skills training component.

Consultation: In standard DBT, therapists engage with clients by phone to help improve clients' ability to seek help when needed. However, none of the reviewed articles described any telephone contact taking place (Valentine et al., 2015).

Therapist Consultation Groups: Standard outpatient DBT generally includes weekly consultation meetings among therapists. Six of the studies incorporated either once- or twice-weekly therapist consultation meetings in their treatment plans.

Comparison Groups: Of the twelve studies included, nine conducted comparison analyses between a group that received DBT and a group that received either CBT or another type of depression or anxiety intervention.

Thematic Area 2: Treatment Outcomes

Across all 12 studies, the groups receiving DBT reported improvements in at least one symptom or problematic behavior. Some individuals reported behavioral changes in more than one area of concern.

Depressive Symptoms: Of the eight studies that examined depressive symptoms, six reported a considerable reduction in symptoms following DBT treatment. Many of the behavioral improvements were maintained for up to 21 months post-discharge. One study also reported a reduction in depressive symptoms, though the difference was not substantially greater than that observed in the comparison group receiving CBT.

Anxiety Symptoms: Three studies investigated anxiety symptoms. In two of those studies, symptoms were reduced and improvements were 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 diseases, 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 a cost of approximately $36.70 more than standard care alone. These findings indicate that DBT is more effective and modestly more costly than usual care in the treatment of comorbid anxiety and depression in adults (Garber & Weersing, 2010; Matusiewicz et al., 2010).