Sudden gains in interpersonal psychotherapy for depression.

Sudden, precipitous improvements in depressive symptom severity have been identified as occurring among unipolar depressed individuals. These "sudden gains" have been associated with superior acute treatment outcome in several treatment modalities, including cognitive therapy. A better understanding of sudden gains may provide insight into the mechanisms of action in these and other psychotherapies. One efficacious therapy that has been overlooked in sudden gains research is interpersonal psychotherapy (IPT; Weissman, M. M., Markowitz, J. C., & Klerman, G. L. (2000). Comprehensive guide to interpersonal psychotherapy. New York: Basic Books). The present research examined the rates and concomitant features of sudden, precipitous improvements in depressive symptomotology among 185 women receiving IPT for recurrent depression. Sudden gains, defined using extant criteria for the Beck Depression Inventory, were assessed over 12 weeks of acute IPT treatment for depression and occurred for 33.5% of the sample. Sudden gains were not associated with diagnostic and demographic characteristics or with differential likelihood of achieving depression remission with IPT monotherapy during active treatment. Further, those with sudden gains were no more likely to maintain their recovery through maintenance treatment. The lack of impact of sudden gains on eventual outcome is discussed in terms of potentially disparate emphases and mechanisms of change between IPT and cognitive-behavioral therapy (CBT).