Davanloo's Intensive Short-Term Dynamic Psychotherapy in a tertiary psychotherapy service: overall effectiveness and association between unlocking the unconscious and outcome.

Background. Intensive Short-Term Dynamic Psychotherapy (ISTDP), as developed by Habib Davanloo, is an intensive emotion-focused psychodynamic therapy with an explicit focus on handling resistance in treatment. A core assumption in ISTDP is that psychotherapeutic effects are dependent on in-session emotional processing in the form of rise in complex transference feelings that occurs when treatment resistance is challenged. Recent research indicates that an unlocking of the unconscious, a powerful emotional breakthrough achieved at a high rise in complex transference feelings, can potentially enhance ISTDP's effectiveness. While ISTDP has a growing evidence base, most of the research conducted has used small samples and has tested therapy delivered by expert therapists. The aims of this study were to evaluate the overall effectiveness of ISTDP when delivered in a tertiary psychotherapy service, and to investigate if having an unlocking of the unconscious during therapy predicted enhanced treatment effectiveness. Methods. A total of 412 patients were included in the analyses. The average length of treatment was 10.2 sessions (SD 13.3). Multilevel growth curve modeling was used to evaluate treatment effectiveness and the association between unlocking the unconscious and outcome. A number of control predictors including type of treatment resistance were selected and included in the analyses. Outcome measures were the Brief Symptom Inventory (BSI) and the Inventory of Interpersonal Problems (IIP). About half of the patients in the study were treated by therapists in training and the other half by more experienced therapists. Results. Growth curve analyses using the full intention-to-treat sample revealed significant within-group effects of ISTDP on both the BSI and the IIP. Effect sizes were large (>0.80). Unlocking the unconscious during therapy was associated with significantly larger treatment outcome. The relationship was further moderated by type of treatment resistance. Conclusion. This study adds to the empirical base of Davanloo's ISTDP with confirmed treatment effectiveness in a large-scale patient sample when ISTDP was delivered by therapists with a range of experience. Furthermore, emotional mobilization in the form of unlocking the unconscious was confirmed as a process factor enhancing the effectiveness of ISTDP.