Processes of change in a randomized clinical trial of radically open dialectical behavior therapy (RO DBT) for adults with treatment-refractory depression.

Radically open dialectical behavior therapy (RO DBT) is an empirically supported psychotherapy for treatment-refractory depression (TRD) that targets psychological inflexibility and interpersonal functioning within the context of maladaptive overcontrol. However, it is unknown whether change in these mechanistic processes is associated with decreased symptoms. This study tested whether change in psychological inflexibility and interpersonal functioning is associated with change in depressive symptoms in RO DBT.Adults with TRD from The Refractory Depression: Mechanisms and Efficacy of RO DBT (RefraMED) randomized controlled trial of RO DBT, n = 250; M (SD) age = 47.2 (11.5); 65% female; 90% White, were assigned to RO DBT or treatment as usual. Psychological inflexibility and interpersonal functioning were assessed at baseline, 3 (midtreatment), 7 (posttreatment), 12, and 18 months. Mediation analyses and latent growth curve modeling (LGCM) assessed whether change in psychological inflexibility and interpersonal functioning was associated with change in depressive symptoms.The effect of RO DBT in decreasing depressive symptoms was mediated by changes in psychological inflexibility and interpersonal functioning at 3 (95% CI [-2.35, -0.15]; [-1.29, -0.04], respectively), 7 (95% CI [-2.80, -0.41]; [-3.39, -0.02]), and only psychological inflexibility at 18 (95% CI [-3.22, -0.62]) months. LGCM indicated only in RO DBT was a decrease in psychological inflexibility through 18 months associated with a decrease in depressive symptoms (B = 0.13, p < .001).This supports RO DBT theory about targeting processes related to maladaptive overcontrol. Interpersonal functioning, and in particular, psychological flexibility, may be mechanisms that decrease depressive symptoms in RO DBT for TRD. (PsycInfo Database Record (c) 2023 APA, all rights reserved).