Structural features of borderline personality organization mediate the links between personality traits and depressive symptoms.

This study aimed to examine the associations between personality traits, structural features of borderline personality organization, and depressive symptoms, and to test whether borderline organization dimensions mediate the links between healthy personality traits and depressive symptoms. An online survey was conducted with 709 participants (M age = 29.6; 67.6% female) who completed the Patient Health Questionnaire-9 (PHQ-9), the Borderline Personality Inventory (BPI), and the Big Five Markers Questionnaire (IPIP-BFM-50). Data were analyzed using Pearson's correlations and a generalized linear model (GLM) approach for multiple mediation analysis, controlling for gender. Level of depressive symptoms was strongly associated with lower levels of adaptive personality traits and higher levels of structural features of borderline personality organization. Mediation analyses revealed that primitive defenses and fear of fusion consistently mediated the relationships between most personality traits (especially emotional stability) and depressive symptoms, underscoring their central role as indirect pathways of vulnerability. These findings highlight the central role of low emotional stability and associated structural features of borderline personality organization-particularly primitive defenses and fear of fusion-in shaping depressive symptoms, emphasizing key clinical targets for intervention.