Supplementary Material for: Learn to control your anger: Neural effects of mechanism-based anti-aggression psychotherapy in borderline personality disorder

Introduction:
Severe anger and overt aggression are common phenomena in borderline personality disorder (BPD) which has serious negative consequences for those affected and their environment. New developments in psychotherapy for personality disorders aim to target etiological mechanisms involved in psychopathology. Since affect dysregulation is a prominent biobehavioral mechanism underlying overt aggressive behavior in BPD, we aimed to clarify whether a psychotherapy that has been shown to decrease aggression in BPD does indeed modulate this mechanism.
Methods:
Accordingly, the neural effects of a novel mechanism-based anti-aggression psychotherapy (MAAP) were compared to those of a non-specific supportive psychotherapy (NSSP). 27 highly overt aggressive patients with BPD and 29 healthy controls were included in the fMRI study.
Results:
The BPD patients treated with MAAP showed an increase in neural activation in clusters comprising the left anterior insula, the right dorsomedial prefrontal cortex (PFC) and the bilateral anterior caudate being related to a reduction in overt aggression. In contrast, the BPD group that had received NSSP exhibited a decrease in activity in the aforementioned clusters, each associated with a rise in overt aggressive behavior. Furthermore, MAAP showed an increase and NSSP a decrease in context-dependent functional connectivity between the caudate seed cluster mentioned above and the left dorsolateral PFC. Likewise, this interaction effect was negatively related to the change in overt aggression with an OAS-M reduction for the MAAP and a rise for the NSSP group.
Conclusion:
The data may suggest that the aggression reducing effect of MAAP is mediated through increasing cognitive control over dysregulated feelings of anger.