Oxytocin plasma levels predict the outcome of psychotherapy: A pilot study in chronic depression

Background: Oxytocin is associated with bonding and social deficits in psychiatric disorders and has also been discussed as a potential therapeutic intervention to augment psychotherapy. The Cognitive Behavioral Analysis System of Psychotherapy (CBASP) is a specific form of psychotherapy for chronic depression, an illness in which interpersonal deficits play a major role. In this pilot study, we investigated whether Oxytocin plasma levels predict the clinical outcome of chronic depressive patients after CBASP. Methods: Sixteen patients with chronic depression participated in a 10-week CBASP inpatient program. Oxytocin plasma levels were measured before and after participants played a virtual ball-tossing game (Cyberball) that mimics social exclusion. Clinical outcome after CBASP was evaluated with the Beck Depression Inventory-II (BDI-II) and the 24-item Hamilton Depression Rating Scale (HAMD-24). Results: After CBASP, depressive symptoms decreased significantly: the response rates were 44% (BDI-II) and 50% (HAMD-24); and the remission rates, 38% (BDI-II) and 44% (HAMD-24). Lower oxytocin plasma levels at baseline correlated with smaller changes in BDI-II scores, but not with the change in HAMD-24 scores. Limitations: The limitations of our study were the small sample size, concomitant and non-standardized pharmacotherapy, and lack of a controlled design and a follow-up period. Conclusions: Our study provides first evidence that oxytocin plasma levels may predict the outcome of psychotherapy in chronic depression. These findings need to be replicated in larger randomized, controlled trials.