Background: Research in the field of psychotherapy suggests that Emotional Arousal (EA) might be a key element to therapeutic success. However, its relevance depends on a situation-bound complex process, requiring its assessment at the right time and in relation to significant personal themes. Methods: This paper is a secondary analysis of a 4-month treatment RCT with two arms (General Psychiatric Management and Treatment As Usual) for Borderline Personality Disorder (BPD). 55 clients with BPD (GPM group: n = 28; TAU group: n = 27) as well as healthy controls (n = 29) participated in the study. We assessed them (intake, 2 months and discharge for the BPD group and intake and at consistent intervals for the healthy controls) using an experiential two-chair dialogue focused on the client’s self-criticism, ensuring the idiosyncratic relevance of the aroused state. We evaluated EA during the two-chair dialogue at three time-points (two for the controls) over the course of treatment via self-reported (Self-Assessment Manikin) and observer-rated (Client Emotional Arousal Scale-III) scales as well as borderline symptomatology (ZAN-BPD) and general psychological distress (Outcome Questionnaire 45). Results: In line with our expectations, we find that participants with diagnosed BPD show higher EA variance compared to controls. This heightened EA variance changes range over the course of the 4-month psychiatric treatment, with participants in the control and BPD groups showing levels of EA variance that are not significantly different at T3. There is no evidence that lower EA variance is associated with reduced symptoms. Discussion: In the treatment of BPD, change in EA variance may be a key element as it normalises throughout the brief intervention. However more research is needed to clarify the relationship between this normalisation and symptom reduction.

Background: Research in the field of psychotherapy suggests that Emotional Arousal (EA) might be a key element to therapeutic success. However, its relevance depends on a situation-bound complex process, requiring its assessment at the right time and in relation to significant personal themes. Methods: This paper is a secondary analysis of a 4-month treatment RCT with two arms (General Psychiatric Management and Treatment As Usual) for Borderline Personality Disorder (BPD). 55 clients with BPD (GPM group: n = 28; TAU group: n = 27) as well as healthy controls (n = 29) participated in the study. We assessed them (intake, 2 months and discharge for the BPD group and intake and at consistent intervals for the healthy controls) using an experiential two-chair dialogue focused on the client’s self-criticism, ensuring the idiosyncratic relevance of the aroused state. We evaluated EA during the two-chair dialogue at three time-points (two for the controls) over the course of treatment via self-reported (Self-Assessment Manikin) and observer-rated (Client Emotional Arousal Scale-III) scales as well as borderline symptomatology (ZAN-BPD) and general psychological distress (Outcome Questionnaire 45). Results: In line with our expectations, we find that participants with diagnosed BPD show higher EA variance compared to controls. This heightened EA variance changes range over the course of the 4-month psychiatric treatment, with participants in the control and BPD groups showing levels of EA variance that are not significantly different at T3. There is no evidence that lower EA variance is associated with reduced symptoms. Discussion: In the treatment of BPD, change in EA variance may be a key element as it normalises throughout the brief intervention. However more research is needed to clarify the relationship between this normalisation and symptom reduction.