Background: In attempting to explain borderline personality disorder (BPD) researchers have paid particular attention to biological factors, i.e. temperament, and to parental influence, especially involving early childhood trauma. The goal of our research was to determine what traumatic factors (early childhood trauma affecting attachment style, defensive dissociation, and the experience of trauma in adolescents and adulthood) and non-traumatic factors (temperament) influence the development of BPD. Material/Methods: The Polish version of Leischenring's Borderline Personality Inventory (BPI) was used to identify a group of persons with this disorder. Attachment style was measured using Fraley and Brenn's Experiences In Close Relationships - Revised; temperament was measured using Zawadzki and Strelau's FCZ-KT Temperament Questionnaire; the intensity and areas of dissociation were measured with Juris's Dissociation Scale; and trauma in adolescence and childhood was measured with Essenski's Trauma Questionnaire. We examined 134 students, ranging in age from 24 to 45 years; 65% were women. In this group, 37 showed signs of BPD. Results: Step-wise regression analysis revealed that the four domains of the BPI (identity diffusion, primitive defense mechanisms, impaired reality testing, and fear of closeness) are associated with the fearful or avoidant attachment style, the use of dissociative mechanisms, and sensitivity as a feature of temperament. Conclusions: The four dimensions of BPD are primarily conditioned by early childhood trauma and dissociation as a defense mechanism. Trauma in adolescence and adulthood did not correlate with the intensity of borderline symptoms.
