Investigation of content and therapeutic change : a comparison of cognitive behaviour therapy and interpersonal therapy in the treatment of depression

Background Different therapies have different theoretical backgrounds which makes their comparison difficult. Process research seeks to understand what the common mechanisms are at work which contribute to successful outcome. The current study sought to compare the content of two therapies (Cognitive Behaviour Therapy and Interpersonal Therapy) in the treatment of depression and measure any changes that participants reported. Method Taped therapy sessions of IPT and CBT were transcribed and a coding scheme measuring content of therapy was developed. Participants’ accounts of therapeutic change were recorded between the two models of therapy across three time periods using a mixed design. The times periods were divided into: beginning, middle and end of therapy. Quantitative content analysis was used to measure frequency of occurrence of categories in therapy. Qualitative Content Analysis was used to compliment quantitative findings and to compare participants' accounts of change between the beginning and end of therapy. Results The results indicated that differences in content reflected the theoretical background of both therapies. The categories: affect expression, task activation and review, behavioural change and cognitive change, solution generation, discussion of the model, homework and assumptions occurred significantly more in CBT compared to IPT. All other differences between the models were not significant. Differences in content of therapy occurred between the beginning, middle and end of therapy. There was a reduction in symptoms of depression for participants in both groups as measured by the BDI but this reduction was not significant. The discussion related the findings to the current literature and presented ideas for future research.