Level of identity diffusion in patients with borderline, narcissistic, avoidant and other specified personality disorder

Traditional conceptions of personality disorder (PD) view severe identity disturbance as a defining characteristic of borderline personality disorder (BPD). In the alternative DSM-5 model for PDs (AMPD) and in the outlined substantial changes to PD diagnostics in ICD-11, disturbances in self and identity are elevated from a specific diagnostic criterion for BPD to a defining criterion for PD in general. In line with Kernberg's theory of personality organization (PO), it is expected that although identity disturbance may be characteristic of most or all PDs, severe identity diffusion is a more pronounced and defining characteristic of BPD and possibly other PDs organized on a borderline level (BPO). Here, we examined the level of identity disturbance in SCID-diagnosed patients with BPD, narcissistic PD (NPD), avoidant PD (AVPD), comorbid BPD with NPD and AVDP, as well as other specified PD (PD-OT). We found that measures of identity diffusion were higher in BPD and NPD patients compared with patients diagnosed with AVPD. Hierarchical multiple regression analyses showed that number of SCID criteria met for BPD and NPD predicted level of identity diffusion when gender, age and general symptomatology were controlled for, whereas number of SCID criteria met for AVPD did not. The presented data support severe identity diffusion as a prominent characteristic of BPD with possible implications for how we should differentiate BPD from other PDs. The findings are discussed in relation to Kernberg's model and the AMPD.