Around 50% of chronically-depressed patients fail to respond to trials of antidepressants or psychotherapy and an additional 20% do not get completely better. Even after partial improvement a residue of depression can affect people's lives and increase their chances of a relapse. Doctors often add psychotherapy to a drug treatment if this fails to work but there is little research on this. A team of researchers from the U.S. working on the REVAMP (Research Evaluating the Value of Augmenting Medication with Psychotherapy) project studied 491 people who were either not responding, or only partially responding, to antidepressants. They compared one group receiving cognitive behavioural analysis, one group receiving brief supportive psychotherapy and one group just receiving medication, all over a 12-week period. They found that although 37.5% of the participants showed at least some improvement over the course of the study there was no significant difference between the three groups. But it could be the case that a longer study would have shown more improvement in the psychotherapy groups or that different kinds of psychotherapy would have been more effective.
Kocsis, James H. ... [et al] - Cognitive behavioral analysis system of psychotherapy and brief supportive psychotherapy for augmentation of antidepressant nonresponse in chronic depression: the REVAMP trial Archives of General Psychiatry November 2009, 66(11), 1178-1188