Background: Borderline personality disorder (BPD) is defined by a pervasive pattern of instability. According to prior findings and clinical theories, self-esteem instability and affective instability are key features of BPD. Previous e-diary studies showed that instability in self-esteem is heightened and that it is highly intertwined with affective instability in BPD in comparison to healthy controls (HC). The present study sought to extend these findings by adding symptomatologically remitted BPD patients (BPD-REM), i.e. former patients with BPD who met four or fewer BPD criteria within the past year, as a comparison group.
Methods: To examine differences regarding self-esteem instability and affective instability, we used e-diaries for repeatedly collecting data on self-esteem, valence, and tense arousal 12 times a day for four consecutive days while participants underwent their daily life activities. Determining three different state-of-the-art instability indices and applying multilevel analyses, we compared 35 BPD-REM participants with previously reported 60 acute BPD patients (BPD-ACU) and 60 HC.
Results: Our results revealed that self-esteem instability was significantly lower in the BPD-REM compared to the BPD-ACU group, irrespective of the instability index. In contrast, there were no significant differences regarding affective instability between the BPD-REM participants and those in the BPD-ACU group. The comparison between the BPD-REM with the HC indicated both a significantly higher instability in self-esteem as well as significantly heightened affective instability in the BPD-REM participants. Moreover, even though the associations were not significant, we found tentative support for the assumption that affective changes that are accompanied by changes in self-esteem are experienced as more burdensome and negatively impact the quality of life of remitted BPD participants.
Conclusions: This study builds on growing evidence for the importance of self-esteem instability in BPD. Whereas affective instability has been reported in various psychiatric disorders and might indeed constitute a transdiagnostic marker of affective dysregulation, our results indicate that self-esteem instability might be a specific symptom that construes the unique pathology in BPD.