The Effects of Dialectical Behavior Therapy on Joy: A Diary Card Study

Dialectical behavior therapy (DBT) has been shown to reduce self-injurious behavior and other maladaptive behaviors in individuals with borderline personality disorder (BPD). Much attention has been paid to changes in negative affect and behaviors. However, few studies have examined the impact of DBT on positive affect (PA). The current study investigates the temporal course of joy, as reported on daily diary cards, in adults with BPD receiving a 6-month course of comprehensive DBT (N=95). BPD severity was measured every four weeks. Results showed that joy increased significantly during treatment, whereas negative affect decreased. Semi-parametric time-varying effect models showed that increases in joy were steeper earlier in treatment and plateaued around month four of treatment. Additionally, within-person increases in joy during a given month predicted decreases in BPD severity at the end of that month. Our results suggest that PA may be an important treatment target deserving of further clinical attention in in DBT, given that it prospectively predicts reductions in BPD symptom severity. Our finding that joy increases during DBT, particularly in early stages of treatment, may be an important incentive to bolster treatment uptake and commitment.