Both borderline personality disorder (BPD) and childhood trauma have been shown to be associated with affect dysregulation, dissociation, and fear-based attachment schemas. However, the inter-relationships of these clinical phenomena have not been studied in unison.

To study the interrelations between childhood psychological trauma and adult BPD mediated by dissociation, attachment schemas, and affect dysregulation in unison while differentiating for inhibitory- and excitatory regulation symptoms.

Adult chronic psychiatric patients with BPD, BPD with comorbid somatoform disorder, and two psychiatric control groups with SoD-only, or chronic anxiety or affective disorders com-pleted structured interviews and self reports. Affect dysregulation, fear-based attachment schemas and dissociation were tested simultaneously -in their separate inhibitory- and excitatory form- as potential mediators in the relationship between childhood psychological trauma and BPD symptoms in adulthood. Next, two alternative models partitioning childhood trauma into more specific features as source (primary-caretaker or not), or type i.e. emotional-, physical-, or sexual abuse, while differentiating for developmental epochs, were compared to the original model. Analyses were re-run for participants who report more severe symptoms that meet criteria for a BPD diagnosis.

Structured equation modeling with bootstrap 95% confidence intervals revealed that hallmark features of BPD – affect dysregulation involving extreme emotional intensity and lability (under-regulation), fragmentation of consciousness (positive psychoform dissociation; e.g., flashbacks), and core attachment fears of closeness and abandonment – partially account for the relationship between overall childhood trauma and BPD-symptom severity. The unifying theme for these mediators is excitatory dysregulation. Alternative models distinguishing types and nature of trauma did not fit the data. However, adults who report more severe symptoms that meet criteria for a BPD diagnosis were likely to have experienced sexual trauma in early childhood or adolescence, and to have an intense fear of abandonment, with the path from early childhood sexual trauma to BPD symptoms as strongest direct relationship.

Relationships between overall childhood trauma and BPD symptoms in adulthood through three mediators i.e., affect dysregulation, fear-based attachment schemas and dissociation were found, over alternative models distinguishing types of perpetrator, nature of trauma, and developmental epoch. These findings contribute to and replicate a substantial research base that highlights sexual trauma in early childhood and severe attachment insecurity (and disorganization) as contributors to adult BPD. Prospective studies are needed to elucidate the complex relationships between childhood trauma and BPD.