by Michael D. Anestis, M.S.
A large portion of my early clinical training focused on the cognitive behavioral analysis system of psychotherapy (CBASP), a form of psychotherapy deveoped specifically for the treatment of chronic depression. We have detailed the nature of this treatment before and I have truly enjoyed utilizing it in sessions, but I'm always on the lookout for new studies examining its efficacy and/or effectiveness, as the evidence base for this treatment is not as strong as I would like. Yesterday, I came across a new study just published in the Journal of Affective Disorders by Elisabeth Schramm and colleagues (2011) that compared CBASP and interpersonal psychotherapy (IPT) in the treatment of early-onset chronic depression and I'd like to summarize the results for you in an effort to add to our earlier discussion of the treatment. The study provides an important addition to the literature, as it compares CBASP to another empirically supported active treatment rather than waitlists of psychopharmacology.
In this particular study, all participants were between the ages of 18 and 65 and met DSM-IV criteria for one of the following diagnoses, as determined through semi-structured diagnostic interviews:
- Current episode of chronic depression
- Depression superimposed on pre-existing dysthymia
- Recurrent depression without full interepisode recovery in a patient with current depression and a total duration of at least two years
Additionally, the authors were specifically interesting in early onset chronic depression, so all participants needed to have experienced their first depressive episode prior to age 21. All participants needed to present with a score of at least 16 on the Hamilton Rating Scale for Depression (HRSD, Hamilton, 1967). Unfortunately (in my opinion), participants were excluded if they were at acute risk for suicide, although this is a common occurrance in treatment research.
The authors randomized 30 patients to 22 sessions of either CBASP or IPT and sessions were delivered over a period of 16 weeks. Participants were assessed at baseline, at the end of treatment, and at a twelve month follow-up, allowing not only for an examination of the impact of treatment when therapy was still fresh in the patients' minds, but also of the longer term impact of each form of therapy.
During the course of treatment, patients in the CBASP group exhibited a significant decrease in clinician-rated depression symptoms (23.00 to 11.21), whereas the patients in the IPT group did not demonstrate a statistically significant drop (23.27 to 18.87). That being said, the post-treatment scores in the two groups (11.21 vs 18.87) were not statistically different from one another. In order for the authors to detect significant differences like this, they would really need more patients in each group (this is the issue of statistical power); however, we can not say for sure that, had there been more patients, the results would have been the same and the difference would be significant. The authors also administered a measure of self-reported depression symptoms. Both the CBASP (25.43 to 10.79) and the IPT (28.47 to 21.27) groups exhibited sigificant drops in their scores on this measure (Beck Depression Inventory; BDI). With respect to self-reported depression symptoms, improvement in the CBAST group was significantly greater than in the IPT group.
At the end of treatment, the response rate in the CBASP group (64.3%) was significantly greater than the rate in the IPT group (26.7%). Similarly, remission rates in the CBASP group (57.1%) was higher than the rates in the IPT group (20.0%). Both groups improved in the global assessment of functioning (GAF), with no significant differences between the two groups on that outcome.
A year after treatment ended, patients were assessed again. 75.9% of the total sample (57% of CBASP, 93% of IPT) participated in the follow-up assessment. At 12-month follow-up, both groups demonstrated significant decreases in symptoms and CBASP no longer outperformed IPT on self-reported depression symptoms, although it did outperform IPT on an assessment of general adaptation.
So what does all of this mean? In the end, the results immediately post-treatment favor CBASP, but by 12-month follow-up, the results appear to be essentially equal. This is not particularly surprising, as studies examining IPT versus CBT for particular diagnoses (e.g., bulimia nervosa) have presented similar patterns: CBT results in quicker improvement, but IPT catches up over time. In the end, this is good news. Both treatments resulted in improvements despite being extremely different from one another. Both treatments are manualized and evidence-based, but CBASP is substantially more structured than is IPT. As such, patients have an opportunity to choose from two very different approaches if they present with chronic depression.
If you would like to learn more about the topics discussed on PBB, we recommend that you consult our online store for scientifically-based psychological resources.