Trajectories and Processes of Symptom Change Over Time in Dialectical Behavior Therapy for Borderline Personality Disorder.

Despite ample evidence for Dialectical Behavior Therapy (DBT) as an effective treatment for borderline personality disorder (BPD), close examination of the trajectory of change in BPD symptoms over the course of DBT is lacking. There also remain questions regarding the directionality of changes in different domains of BPD symptoms, such as improvements in dysfunctional behaviors and thoughts/feelings. In order to provide more fine-grained information about the treatment process in DBT, the current study aimed to (a) examine the trajectories of change of BPD-associated negative thoughts/feelings and behaviors, and positive behaviors, and (b) test the temporal relationship between changes in negative behaviors and thoughts/feelings. The study involved 55 adult clients attending a 6-month outpatient DBT program for BPD who completed assessments of BPD symptoms every four sessions. Growth curve models suggested that clients experienced a faster rate of decrease in negative behaviors during the initial phase of treatment, whereas steady rates of improvement were found for negative thoughts/feelings and positive behaviors, respectively, throughout treatment. Further, a random-intercept cross-lagged panel model found that the within-person fluctuations in negative behaviors preceded the within-person changes in negative thoughts/feelings at a subsequent time point during the later phase of treatment, whereas within-person fluctuations in thoughts/feelings were followed by changes in negative behaviors at the beginning and end of the treatment. These results highlighted the complexity of patterns and processes of change in BPD symptomatology during the course of DBT.