This chapter reviews how personality disorder assessment, conceptualization, and treatment can be enhanced by considering interpersonal models. Contemporary Integrative Interpersonal Theory (CIIT) provides conceptual grounding to interpersonal models, which are often constructed around the two dimensions of agency and communion. Agency captures the theme of achievement, status, control, and differentiation, whereas communion captures the theme of connectedness, union, solidarity, and friendship. The authors discuss how personality disorder patients often struggle with agency and communion, and review research articulating how personality disorders are associated with specific impairments in agency and communion in cross-sectional and longitudinal research designs. They also propose a fifth assumption to CIIT to integrate emerging literature on pathological interpersonal patterns in personality disorders. This assumption emphasizes the importance of context in characterizing non-normative social exchanges beyond simple deviations from complementarity. They conclude by discussing how concepts in interpersonal models can be used to inform and implement therapy for patients with a personality disorder.

This rejoinder discusses four areas for growth articulated by the commentaries provided on the initial chapter. The authors add greater specificity for how interpersonal styles can inform therapy approaches. They discuss how static and dynamic conceptualizations of personality disorder can be approached from an interpersonal framework. They agree with Durbin about the importance of relationship context and discuss how interpersonal models can be applied to specific relationship contexts. Finally, they reassert the importance of context in understanding interpersonal processes, while recognizing that “context” is embedded through many of the interpersonal assumptions.

Sanislow and Hector (this volume) provided a comprehensive review of the Cluster C personality disorders (PDs) with an emphasis on articulating anxious-fearful pathology and avoidance behavior. The authors provided historical context for the Cluster C PDs within the DSM and reviewed relevant research findings with a particular focus on how Cluster C pathology can be understood within NIMH RDoC domains. There is much to appreciate in their chapter and this commentary offers points intended to augment their review of Cluster C pathology. It is suggested that interpersonal theory provides a useful framework for understanding personality pathology and a review of relevant research investigating interpersonal functioning in Cluster C PDs is provided.

Although there are many pathways to suicide, studies in the domains of neuropsychology, cognitive psychology, neurobiology, and clinical psychiatry provide increasing evidence in support of a stress–diathesis model of suicidal behavior. While depression is the common final pathway to suicidal behavior, the vast majority of depressed individuals neither attempt nor complete suicide. It appears that a diathesis to suicidal behavior differentiates depressed individuals who will kill themselves from other depressed patients. The diathesis may be due to (epi-)genetic effects and childhood adversity, and is reflected by a distinct biological, psychological and clinical profile. This chapter will first review stress-diathesis models of suicidal behavior, ranging from cognitive models such as the “cry of pain” model to a neurobiological model in which deficient decision-making and its neural basis are central issues. Second, implications for treatment and prevention will be discussed. The identification of diathetic traits can be expected to facilitate early recognition of suicide risk. Vulnerability traits are open to modification early in life, and interventions during sensitive periods of development may have durable effects on vulnerability and resilience. The antisuicidal effects of drugs such as lithium and clozapine may well exert such effects via neurobiological components of the diathesis such as the serotonergic neurotransmission system.