Treating Bulimia Nervosa with Cognitive-Behavioral Therapy and Interpersonal Psychotherapy

Interpersonal Psychotherapy as a Mode of Treatment for Bulimia Nervosa

Interpersonal psychotherapy (IPT) is a short-term focal psychotherapy in which the primary aim is to help patients identify and modify current interpersonal problems. It was developed in the 1940's as a treatment for clinical depression. However, IPT for depression has been modified as a treatment for bulimia nervosa.

The rationale for using IPT as a treatment for bulimia nervosa maintains that episodes of binge eating and purging may be influenced by interpersonal problems such as role disputes, role transitions and interpersonal deficits. Thus, the interpersonal context may serve to maintain and perpetuate the condition and procedures that identify and resolve underlying interpersonal problems is essential in treating the disorder.

Interpersonal psychotherapy for bulimia has three phases. In the first phase, the goal is to identify current interpersonal problems and decide which will be addressed in the remainder of treatment. Problem areas are identified by evaluating the interpersonal context in which the eating disorder developed as well as the conditions that maintain the disorder. In addition, the patient’s current interpersonal functioning is assessed and the interpersonal context in which the bulimic episodes occur are examined. In the second phase, the interpersonal problems that have been identified are addressed and the patient makes the necessary interpersonal changes in the identified problem areas.

The third phase addresses the patient’s progress and involves a discussion of how to deal with future interpersonal problems. It is important to note that in IPT, no attention is directed at the patient’s eating habits or attitudes about shape and weight. Thus, the educational, cognitive and behavioral components used in CBT are excluded.

Evidence Supporting the Efficacy of Interpersonal Psychotherapy for the Treatment of Bulimia Nervosa in Young Women

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Interpersonal psychotherapy was originally developed for the treatment of depression. The main aim of adapting IPT for the treatment of bulimia nervosa was to compare it to CBT in treatment trials. As a result, subsequent research has focused mainly on randomized controlled trials comparing IPT to CBT and other kinds of therapy for the treatment of bulimia nervosa. The main findings of these studies will be discussed below.

A Comparison of Cognitive-Behavioral Therapy and Interpersonal Psychotherapy for the Treatment of Bulimia Nervosa in Young Women

Research suggests that CBT is the most effective form of psychotherapy in the treatment of bulimia nervosa in young women. However, several studies have found that interpersonal psychotherapy might be as effective as CBT, although slower to achieve improvements in patients (Fairburn et al., 1993; Agras et al., 2000).

A randomized controlled trial by Fairburn et al (1993) compared the effects of interpersonal psychotherapy, behavior therapy and cognitive behavior therapy among a group of young women diagnosed with bulimia nervosa (Fairburn et al., 1993). The findings of this study suggest that although IPT was inferior to CBT at the end of treatment, these differences disappeared during a 12- month follow-up. Both CBT and IPT resulted in a marked reduction in the frequency of binge eating and purging, and these improvements were sustained during the follow up period. In addition, both treatments resulted in substantial decreases in dietary restriction with no significant difference between the two treatment groups during follow up.

The authors concluded that CBT and IPT achieved equivalent effects through the operation of different mechanisms. Accordingly, CBT appears to operate by directly modifying the patient’s eating patterns and attitudes to weight and shape. However, IPT appears to be acting indirectly (since no attention was paid to eating habits and attitudes about weight and shape). A number of explanations about the mechanism of action of IPT have been offered (Fairburn, 1997). One such explanation is that IPT may provide patients with a sense that they are capable of influencing their interpersonal lives which may decrease their need to control their eating, shape and weight. The two different mechanisms of action for both treatments could explain the temporal difference in patient response. If this is the case, CBT was faster in achieving improvements in the primary behavioral symptoms of bulimia because it was directly acting on changing eating habits.

These findings are significant because they are the first to provide empirical support for a treatment of bulimia nervosa that demonstrates effects equivalent to those of CBT. In addition, since IPT focuses on identifying and changing the interpersonal context in which the behavior occurs, these findings suggest that the disorder can be treated with some success without directly addressing the disturbed eating habits and attitudes. However, one could argue that the sample size used in this particular study was modest (N=75). In addition, the study was based at only one treatment site. In the context of these limitations, the extent to which the findings are reliable and generalizable needs to be taken into account.

As a follow up to the Fairburn et al study, a multisite trial conducted by Agras et al (2000) compared CBT with IPT for bulimia nervosa among young women using a larger sample size (N=220) at two different treatment sites (Agras et al, 2000). According to the findings of this study, CBT was substantially superior to IPT at the end of treatment. Of the patients with bulimia who completed treatment only 8% of those treated with IPT had stopped binge eating and purging compared to 45% of those treated with CBT. However, at follow-up there was no significant difference in outcome between the two treatments. It could be the case that the women who were treated with CBT maintained improvements after treatment (this has been supported by previous research) while those receiving IPT gradually continued to improve because of the different mechanisms of action between the two treatments.

The authors concluded that “CBT was significantly more rapid in engendering improvements in patients with bulimia nervosa than IPT and thus should be considered the preferred psychotherapeutic treatment for the disorder.” (Agras et al, 2000, p.465). The limitations of the understanding of the exact mechanisms by which CBT and IPT achieve their treatment effects and the role of patient characteristics in mediating treatment outcomes should be taken into consideration when interpreting the current findings. A general limitation of most of the studies that have explored the efficacy of CBT versus IPT in treating patients with bulimia nervosa is the exclusionary criteria that are necessary for randomized controlled trials.

For instance, studies often exclude patients that have co-morbid conditions such as substance abuse, severe depression, or those that are taking any form of psychotropic medication. However, in an actual clinical setting it is highly common for patients with bulimia nervosa to suffer from some other form of psychopathology. Therefore, although a randomized controlled design is highly advantageous, the findings may not be reflective of real world situations.Continued on Next Page »