Temperamental underpinnings of borderline personality disorder and its facets.

Temperament is claimed to be the basis for personality; therefore, discovering the temperamental underpinnings of borderline personality disorder and its facets is crucial for understanding this personality disorder. In this article, we explore these underpinnings by using a new model of temperament, based on the Regulative Theory of Temperament, the Big Two of temperament, and the Circumplex of Personality Metatraits. Two studies were conducted on adults-the first was in a general population sample (N = 315) and the second was in a clinical sample (N = 113) in people with a diagnosis of borderline personality disorder. The following measurements were used: The Screening Instrument for Borderline Personality Disorder (SI-Bord), the Five-Factor Borderline Inventory-Short Form (FFBI-SF), and the Temperament Metadimensions Questionnaire (TMQ). General borderline was explained by Reactivity (high Sensitivity) and Activity (high Dynamism). At the facet level, the Borderline Internalizing Facet was mainly explained by Reactivity (high Sensitivity), while the Borderline Externalizing Facet was explained by Activity (high Dynamism) in addition to Reactivity (high Sensitivity). The results of our study revealed specific temperamental underpinnings of borderline and its facets. Reactivity underlies all borderline facets, while Activity differentiates between the Borderline Externalizing Facet and Borderline Internalizing Facet.