Before Borderline Personality Disorder: a Comprehensive Narrative Review of its Origins and Integrative Models of Etiology

Borderline personality disorder (BPD) is increasingly recognized as the outcome of recursive interactions among genetic, neurobiological, epigenetic, environmental, psychological, and psychodynamic factors rather than as the product of linear causal models. This narrative review synthesizes current evidence across these domains to advance a comprehensive framework for understanding BPD’s developmental pathways. While concepts such as equifinality, multifinality, and differential susceptibility have been sporadically noted in prior work, only a handful of studies explicitly apply them to BPD. To our knowledge, this article provides the most extensive integration of these perspectives to date, situating BPD within a developmental psychopathology model that explains both shared and divergent outcomes across individuals. By emphasizing plasticity alongside vulnerability, we propose an empirically grounded, multifactorial account that holds particular promise for psychiatric understanding as well as psychodynamic and other psychotherapeutic treatments. This integrative approach highlights the complex etiological architecture of BPD and underscores opportunities for tailoring interventions to patients’ unique developmental trajectories.