Neural Signatures of Social Inclusion in Borderline Personality Disorder Versus Non-suicidal Self-injury.

Borderline personality disorder (BPD) is characterized by interpersonal disturbances and dysfunctional behavior such as non-suicidal self-injury (NSSI). We recently observed neural alterations in BPD during social inclusion by enhanced activations within the dorsomedial prefrontal cortex (dmPFC) and the posterior cingulate cortex (PCC). To examine the specificity of these neural alterations, we now investigated participants with NSSI but without BPD and compared them to BPD and healthy controls (HC). Considering the association between NSSI and BPD, we further examined neural commonalities during social inclusion. Fifteen females diagnosed with BPD, 16 with NSSI and 17 HC were investigated by fMRI and the cyberball paradigm, focusing on social inclusion (p < 0.05; FWE on cluster-level). To examine neural commonalities between BPD and NSSI compared to HC, we computed a conjunction analysis on neural activations under social inclusion. Significant increases in neural activation were observed in BPD within the dmPFC under social inclusion compared to NSSI and HC, whereas neural activations within the PCC did not differ between BPD and NSSI. The conjunction analysis revealed a common neurofunctional increase within the pregenual anterior cingulate cortex and the anterior insula in both, BPD and NSSI. We provide a further evidence regarding a disorder-specific neural reactivity within the dmPFC during social inclusion in BPD, whereas PCC activations may represent an unspecific neural alteration in BPD when compared to NSSI. In contrast, both clinical groups revealed a common neural increase within the salience network that may support the assumptions of a developmental continuum between these two psychiatric conditions.