Psychological flexibility, rumination, and avoidance as predictors of outcome in cognitive behavioral therapy for treatment-resistant major depressive disorde

Major depressive disorder (MDD) is associated with rigidity across cognitive, affective, behavioral, and physiological systems. Treatment-resistant and chronic forms of MDD are particularly entrenched and difficult to treat. Recent clinical research suggests that decreasing processes that maintain rigidity, such as rumination and avoidance, and also increasing psychological flexibility, may be important tasks of treatment. However, it is not yet clear whether rumination, avoidance, and flexibility have separate effects, or whether they predict outcomes in a treatment-resistant sample. The current study examined these variables as predictors of treatment outcomes in a sample of patients (n = 49) who received cognitive-behavioral therapy (CBT) for pharmacotherapy-resistant MDD. Rumination, avoidance, and flexibility were coded in therapy sessions that occurred in the vicinity of two key therapeutic transition points: a sudden gain (improvement) and a transient spike in depression symptoms. More flexibility in the sessions that immediately preceded sudden gains (or matched sessions for those who did not experience a sudden gain) predicted less depression at 6- and 12-month follow-ups, beyond baseline symptom severity and flexibility and co-occurring rumination and avoidance. In post-spike (or matched) sessions, only rumination directly predicted more depression after 6-months. Interaction analyses revealed that rumination and avoidance both predicted worse depression at the 12-month follow-up, but only when flexibility was low. At higher levels of flexibility, rumination and avoidance no longer predicted worse outcomes, suggesting a potential buffering effect of flexibility. These findings suggest that flexibility might be an additional important target in CBT for treatment-resistant depression.