Defense mechanisms and psychotherapy change: a systematic review

Defense mechanisms (DMs) are of pivotal importance in the field of psychotherapy. However, to the best of our knowledge, no systematic reviews have addressed their prognostic and explanatory role in psychotherapy change. The present study aims to fill this gap by examining the following research questions: (a) Do DMs change as a therapy outcome? (b) Are DMs predictors of therapy outcome? (c) Are DMs associated with other process variables? A comprehensive database search was conducted through March 2025 for original research on DMs and psychotherapy change. The characteristics of these studies were extracted. The quality of the studies was then rated using a modified version of the Newcastle–Ottawa Scale and the Joanna Briggs Institute Critical Appraisal Checklist for Case Reports. The 46 studies included in the review highlighted DMs’ change throughout the following therapy, their ability to predict outcomes, and their increase in maturity. The trajectory of change was not always linear, and the associations with other process variables highlighted controversial results. The heterogeneity of measures and research designs constrained cross-study comparisons due to differences in the research aim, varying between clinical process and clinical outcome. DMs emerge as meaningful prognostic indicators and markers of change. Future research should standardize timing, adopt repeated assessments, disaggregate within- versus between-patient effects, extend follow-up periods, test moderators (diagnosis, comorbidity, modality), and examine therapists’ defenses as potential mediators.