Lessons from ten years of psychotherapy process research

Objective: The aim of this review is to systematize and interpret results produced over one decade of Psychotherapy Process Research (2009-2019) in eight journals.Method: It is a Mixed Studies Review of quantitative as well as qualitative primary studies. The analysis of the results of these studies included a descriptive quantitative part and a qualitative part that followed the logic of Qualitative Meta Analysis, categorizing the main results of both types of studies in a bottom-up procedure that generates specific content categories that are synthesized in further steps of a higher level of abstraction, leading to an "interpretive synthesis" presented in a narrative way.Results: The review shows that psychotherapy process research uses a variety of qualitative and quantitative methods, often creating new procedures. Furthermore, the review indicates that the most commonly assessed macroprocess variables are ongoing change, therapeutic relationship (predominantly therapeutic alliance), and therapeutic intervention; while the most extensively studied microprocess variables are change events, difficult episodes (mainly ruptures), and therapeutic intervention. Macrolevel results reveal that the main contents of ongoing change are the building of new meanings and progressive psychological integration; underscore the association of the therapeutic alliance with ongoing change and outcome; and show the complexity of associating intervention with outcome, because different phases of therapy (and problems) need different assessments. Microlevel results indicate that change events impact on ongoing change and outcome; that for ruptures the key fact is their repair; and that therapist communication has an immediate influence on patient communication.Conclusion: Our knowledge regarding relevant aspects of psychotherapy is very fragmented; robust and replicated results are still scarce. Only a few variables have been found to consistently predict outcome across most therapies. Only in the field of alliance research it has been possible to perform meta-analyses that clearly demonstrate the impact of this factor on final outcomes. Despite these limitations, psychotherapy process research is a powerful tool for uncovering change mechanisms and is at present widely implemented. Our conclusion is that, in order to generate useful future knowledge, change mechanisms need to be linked to ongoing change; this, in turn, requires models of change, hopefully of a transtheoretical nature.