RESUMO
By now psychotherapy research has provided sufficient evidence in favour of the efficacy of psychotherapy, especially of the cognitive behaviour therapy (CBT). Hence one can argue that psychotherapy truly "works". Nevertheless, the rationale for the efficacy and the underlying mechanisms have not yet been explored. Resolving this ambiguity by focusing on the active ingredients in CBT is the aim of our review. More precisely we have explored whether the therapist's competence or his/her adherence to the CBT protocol is responsible for the therapeutic improvement that many patients sustain subsequent to psychotherapy. By means of a broad literature search we identified a total of nâ=â13 studies, whereby nâ=â7 referred to the impact of therapist's competence and nâ=â7 to the impact of adherence on post-treatment outcome, respectively, and one of these studies referred to both. The meta-analytical evaluation yielded a small significant total effect (râ=â0.24) for the therapist's competence on therapeutic improvement of patients with diverse disorders and a moderate total effect (râ=â0.38) regarding patients with major depression. In contrast, for the case of an influence of adherence to protocol on post-treatment outcome we did not achieve significant results. Therefore a competent performance of cognitive-behaviour techniques on the part of the therapist seems to contribute thoroughly to the therapeutic improvement subsequent to treatment. However, solely a manual-guided implementation of CBT seems not to have a significant impact on patients impromvement. Furthermore, our results indicate that the therapeutic change constitutes an extensive process that has consequently to be understood in future process-outcome research. Finally the implications of our results as well as potentials for future research are discussed.