The paper traces the relationship between attachment processes and the development of the capacity to envision mental states in self and others. We suggest that the ability to mentalize, to represent behavior in terms of mental states, or to have “a theory of mind” is a key determinant of self-organization which is acquired in the context of the child's early social relationships. Evidence for an association between the quality of attachment relationship and reflective function in the parent and the child is reviewed and interpreted in the context of current models of theory of mind development. A model of the development of self-organization is proposed which has at its core the caregiver's ability to communicate understanding of the child's intentional stance. The implications of the model for pathological self-development are explored, with specific reference to the consequences of maltreatment.

The precise nature and etiopathogenesis of borderline personality disorder (BPD) continues to elude researchers and clinicians. Yet, increasing evidence from various strands of research converges to suggest that affect dysregulation, impulsivity, and unstable relationships constitute the core features of BPD. Over the last two decades, the mentalization-based approach to BPD has attempted to provide a theoretically consistent way of conceptualizing the interrelationship between these core features of BPD, with the aim of providing clinicians with a conceptually sound and empirically supported approach to BPD and its treatment. This paper presents an extended version of this approach to BPD based on recently accumulated data. In particular, we suggest that the core features of BPD reflect impairments in different facets of mentalization, each related to impairments in relatively distinct neural circuits underlying these facets. Hence, we provide a comprehensive account of BPD by showing how its core features are related to each other in theoretically meaningful ways. More specifically, we argue that BPD is primarily associated with a low threshold for the activation of the attachment system and deactivation of controlled mentalization, linked to impairments in the ability to differentiate mental states of self and other, which lead to hypersensitivity and increased susceptibility to contagion by other people's mental states, and poor integration of cognitive and affective aspects of mentalization. The combination of these impairments may explain BPD patients' propensity for vicious interpersonal cycles, and their high levels of affect dysregulation and impulsivity. Finally, the implications of this expanded mentalization-based approach to BPD for mentalization-based treatment and treatment of BPD more generally are discussed.

Mentalizing--the capacity to understand others' and one's own behavior in terms of mental states-is a defining human social and psychological achievement. It involves a complex and demanding spectrum of capacities that are susceptible to different strengths, weakness, and failings; personality disorders are often associated with severe and consistent mentalizing difficulties (Fonagy & Bateman, 2008). In this article, we will argue for the role of mentalizing in the therapeutic relationship, suggesting that although mentalization-based treatment may be a specific and particular form of practice, the "mentalizing therapist" is a universal constituent of effective psychotherapeutic interventions.