Development and Psychopathology

Regular Articles

A developmental, mentalization-based approach to the understanding and treatment of borderline personality disorder

Peter Fonagya1 c1 and Patrick Luytena2

a1 University College London

a2 University of Leuven


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.


c1 Address correspondence and reprint requests to: Peter Fonagy, Research Department of Clinical, Educational and Health Psychology, University College London, Gower Street, London WC1E 6BT, UK; E-mail:


The ideas presented in this paper draw on the work of an active group of clinicians and scientists. We thank Anthony Bateman, Linda Mayes, Mary Target, George Gergely, Jon Allen, Efrain Bleiberg, Rudi Vermote, Benedicte Lowyck, and Elizabeth Allison.