Mechanisms of cognitive-behavioral therapy effects on symptoms of body dysmorphic disorder: a network intervention analysis

Abstract

Background: Body dysmorphic disorder (BDD) is a severe and undertreated condition. Although cognitive-behavioral therapy (CBT) is the first-line psychosocial treatment for this common disorder, how the intervention works is insufficiently understood. Specific pathways have been hypothesized, but only one small study has examined the precise nature of treatment effects of CBT, and no prior study has examined the effects of supportive psychotherapy (SPT).

Methods: This study re-examined a large trial (n = 120) comparing CBT to SPT for BDD. Network intervention analyses were used to explore symptom-level data across time. We computed mixed graphical models at multiple time points to examine relative differences in direct and indirect effects of the two interventions.

Results: In the resulting networks, CBT and SPT appeared to differentially target certain symptoms. The largest differences included CBT increasing efforts to disengage from and restructure unhelpful thoughts and resist BDD rituals, while SPT was directly related to improvement in BDD-related insight. Additionally, the time course of differences aligned with the intended targets of CBT; cognitive effects emerged first and behavioral effects second, paralleling cognitive restructuring in earlier sessions and the emphasis on exposure and ritual prevention in later sessions. Differences in favor of CBT were most consistent for behavioral targets.

Conclusions: CBT and SPT primarily affected different symptoms. To improve patient care, the field needs a better understanding of how and when BDD treatments and treatment components succeed. Considering patient experiences at the symptom level and over time can aid in refining or reorganizing treatments to better fit patient needs.

Keywords: Body dysmorphic disorder; cognitive behavioral therapy; mechanisms; network analysis; supportive psychotherapy.

Figure 1.

Regularized networks by assessment point Note. Pre-treatment=week 0 (n = 120). Treatment=weeks 4 (n = 107), 8 (n = 97), 12 (n = 89), 16 (n = 88), 20 (n = 87), and 24 (n = 92). Post-treatment=weeks 37 (n = 84) and 50 (n = 74). Node colors (online only) are as follows: yellow=thoughts, blue=behaviors, pink=insight, white=treatment. Nodes reflect treatment condition and BDD-YBOCS items: Tx=Treatment assignment. ThTim=time occupied by thoughts. ThInt=interference due to thoughts. ThDis=distress due to thoughts. ThRes=resistance of thoughts. ThCon=degree of control over thoughts. BeTim=time spent in repetitive behaviors (i.e., rituals, compulsions) related to body defects. BeDis=distress if repetitive behaviors are/were prevented. BeRes=resistance of repetitive behaviors. BeCon=degree of control over repetitive behaviors. Avoid=avoidance of life activities due to BDD. Insig= BDD-related insight. Higher scores indicate more severe symptoms (e.g., more avoidance, worse insight). Note that items 7 (interference in functioning due to repetitive behaviors) and 12 (avoidance) were collapsed as statistically redundant nodes. Edges (lines) represent pairwise associations. Green edges between symptom (circular) nodes=positive associations. Red edges between symptom nodes=negative associations. Green edges between the binary treatment (Tx; square) node and symptom nodes=CBT associated with more severe symptom than SPT. Red edges between the binary treatment (Tx; square) node and symptom nodes=CBT associated with less severe symptom than SPT. Node size reflects relative difference between treatments in change since baseline. Bigger size=CBT associated with greater symptom improvement than SPT. Smaller size=CBT associated with less symptom improvement than SPT. The size of node ThTim at week 1 reflects negligible difference between groups.