The effects of psychotherapy treatment on outcome in bulimia nervosa: Examining indirect effects through emotion regulation, self-directed behavior, and self-discrepancy within the mediation model

Abstract

Objective: The purpose of this investigation was to examine the indirect effects of Integrative Cognitive-Affective Therapy (ICAT-BN) and Cognitive-Behavioral Therapy-Enhanced (CBT-E) on bulimia nervosa (BN) treatment outcome through three hypothesized maintenance variables: emotion regulation, self-directed behavior, and self-discrepancy.

Method: Eighty adults with BN were randomized to 21 sessions of ICAT-BN or CBT-E. A regression-based bootstrapping approach was used to test the indirect effects of treatment on outcome at end of treatment through emotion regulation and self-directed behavior measured at mid-treatment, as well as the indirect effects of treatment at follow-up through emotion regulation, self-directed behavior, and self-discrepancy measured at end of treatment.

Results: No significant differences in outcome between treatment conditions were observed, and no significant direct or indirect effects were found. Examination of the individual paths within the indirect effects models revealed comparable treatment effects. Across treatments, improvements in emotion regulation and self-directed behavior between baseline and mid-treatment predicted improvements in global eating disorder scores but not binge eating and purging frequency at end of treatment. Baseline to end of treatment improvements in emotion regulation and self-directed behavior also predicted improvements in global eating disorder scores at follow-up. Baseline to end of treatment improvements in emotion regulation predicted improvements in binge eating and baseline to end of treatment increases in positive self-directed behavior predicted improvements in purging at follow-up.

Discussion: These findings suggest that emotion regulation and self-directed behavior are important treatment targets and that ICAT-BN and CBT-E are comparable in modifying these psychological processes among individuals with BN.

Trial registration: ClinicalTrials.gov NCT00773617.

Keywords: bulimia nervosa; cognitive-behavioral therapy; emotion regulation; emotion-focused therapy; integrative cognitive-affective therapy.

Figure 1

Indirect effects of changes in emotion regulation and self-directed behavior on the association between treatment and eating disorder pathology as measured by the EDE Global score. A regression-based bootstrapping approach (5,000 bias-corrected resamples, 95% confidence intervals) was used to examine the hypothesized indirect effects, with treatment type included as the independent variable and baseline EDE global score included as a covariate in each set of analyses. For each of the three mediating variables, two models were conducted. In the first model, the mediating variable was defined as change from baseline to session 14 and the dependent variable was defined as EDE global score at end of treatment. In the second model, the mediating variable was defined as change from baseline to end of treatment and the dependent variable was defined as EDE global score at 4-month follow-up. The figure shows that, in all six models, only the b paths (mediator to dependent variable) were significant. *p < .01 **p < .001

Figure 2

Indirect effects of changes in emotion regulation and self-directed behavior on the association between treatment and eating disorder pathology as measured by binge eating (EDE objective bulimic episode frequency). A regression-based bootstrapping approach (5,000 bias-corrected resamples, 95% confidence intervals) was used to examine the hypothesized indirect effects, with treatment type included as the independent variable and baseline EDE binge eating included as a covariate in each set of analyses. For each of the three mediating variables, two models were conducted. In the first model, the mediating variable was defined as change from baseline to session 14 and the dependent variable was defined as EDE binge eating frequency at end of treatment. In the second model, the mediating variable was defined as change from baseline to end of treatment and the dependent variable was defined as EDE binge eating frequency at 4-month follow-up. The figure shows that, in all six models, only the b paths (mediator to dependent variable) were significant. *p < .01 **p < .001

Figure 3

Indirect effects of changes in emotion regulation and self-directed behavior on the association between treatment and eating disorder pathology as measured by purging (EDE). A regression-based bootstrapping approach (5,000 bias-corrected resamples, 95% confidence intervals) was used to examine the hypothesized indirect effects, with treatment type included as the independent variable and baseline EDE purging frequency included as a covariate in each set of analyses. For each of the three mediating variables, two models were conducted. In the first model, the mediating variable was defined as change from baseline to session 14 and the dependent variable was defined as EDE purging frequency at end of treatment. In the second model, the mediating variable was defined as change from baseline to end of treatment and the dependent variable was defined as EDE purging frequency at 4-month follow-up. The figure shows that, in all six models, only the b paths (mediator to dependent variable) were significant. *p < .01 **p < .001