Invited essay: Identity and borderline personality disorder.

The general consensus is that disturbed identity is one of the defining characteristics of borderline personality disorder. So far it has not been possible to reach a generally accepted definition of identity, and the clinical phenomenon of identity disturbance involves inner subjective states that are not directly accessible to observation and reliable assessment. In this article a preliminary definition of identity is suggested and different levels, dimensions, and categories of identity are delineated. Essential elements of identity disturbance or identity diffusion in BPD patients are described and related to other aspects of borderline personality disorder: mentalization failures, disrupted relationships, impulsive or nonvolitional behavior, deficits in memory, dissociation, and dysfunctional self-narratives.