Neural and Physiologic Correlates of the Therapeutic Alliance: A Narrative Review of International Research

A quality therapeutic alliance, as a component of a successful psychotherapeutic process, provides a trusting relationship and effective collaboration between psychotherapist and client. This narrative review examines research that explores the relationship between psychophysiological measures of psychotherapy participants and their subjective perceptions of alliance quality. The results of 10 empirical articles, selected after a systematic literature search, are presented within several paragraphs. Each of the paragraphs analyzes and discusses studies using measures of the same human body system, followed by recommendations for further research in the conclusion. Thus, as a result of the analysis of the selected sources, the perceived quality of the alliance showed a positive relationship with the synchronization of brain activity indices, heart rate variability, heart rate, skin electrical activity, and breathing patterns between the participants in the process. However, the only study examined the contribution of participants' individual heart rate variability indices, which showed a relationship only for the client alliance. At the same time, the structure of interrelationships between alliance components and psychophysiological parameters differed depending on the number of participants: in dyadic, in family, in the presence of a supervisor or a second therapist. Recorded changes in physiological parameters may reflect both the patterns of participants' cognitive processes and their affective states - and together add to the understanding of the dynamic process of establishing and experiencing an alliance between participants in a psychotherapy session. Future research should unify the research design, continue to clarify the role of interpersonal synchronization in alliance experience, pay attention to differences in couples and group psychotherapy, and examine multiple psychophysiological variables simultaneously using a multilevel approach.