Background: Patients with Major Depressive Disorder (MDD) have been found to have restricted capacity for mentalization, and it is possible that this constitutes a vulnerability factor for developing depression. Due to its focus on linking depressive symptomatology to emotions and interpersonal relations, it was hypothesized that Interpersonal Psychotherapy (IPT) would improve mentalization more than Cognitive Behavioral Therapy (CBT).
Methods: In a randomized controlled trial of 90 patients undergoing IPT and CBT for MDD, Reflective Functioning (RF) was rated from Adult Attachment and from Depression-Specific Reflective Functioning (DSRF) Interviews before and after therapy. Treatment outcome was assessed using the Beck Depression Inventory-II.
Results: The interaction between time and treatment approach was statistically significant, with RF improving significantly more in IPT than in CBT. Change in RF was not correlated with change in depression. The difference in DSRF ratings before and after therapy was not statistically significant for any of the treatments.
Conclusions: IPT may improve mentalization more than CBT. However, although RF increased significantly in IPT, the mean level was still low after therapy. A limitation of the study is the large amount of post-treatment missing data. More research is needed to understand the potential role of mentalization in symptom reduction.
Keywords: cognitive-behavior therapy; interpersonal psychotherapy; major depressive disorder; mentalization; reflective functioning; therapy process.