We hypothesized that compared to therapy groups homogeneously composed of women with binge eating disorder (BED) and low attachment anxiety, groups with high attachment anxiety would have better outcomes and a greater alliance-outcome relationship. We assigned 102 women with BED to therapy groups homogeneously composed of low attachment anxiety (n =52) or high attachment anxiety participants (n=50) who received Group Psychodynamic Interpersonal Psychotherapy (GPIP). GPIP resulted in improved outcomes with large effects. Attachment anxiety condition did not moderate outcomes. However, attachment anxiety condition did moderate the alliance-outcome relationship: i.e., group alliance growth was associated with improved binge eating only in the high attachment anxiety condition. Clinicians should be attentive to and encourage the growth of group therapy alliance especially for anxiously attached individuals.
Trial registration: ClinicalTrials.gov NCT00848367.