Defense Styles Beyond Internalizing and Externalizing Symptoms: A Cross-Sectional Study of Early Adolescent Outpatients

Borderline personality traits (BPTs) in adolescence overlap substantially with internalizing and externalizing symptoms, while defensive functioning is also closely intertwined with these symptom dimensions. Beyond this interdependence, defense styles may provide complementary information about aspects of psychological functioning relevant to BPTs. This secondary cross-sectional analysis examined whether defense styles explain incremental variance in BPTs beyond internalizing and externalizing symptoms in a clinical sample of 110 early adolescents aged 11–14 years. Participants completed the Borderline Personality Features Scale for Children, Youth Self-Report, and Defense Style Questionnaire-40. Associations were examined using correlations and hierarchical multiple regression. BPTs were strongly associated with internalizing symptoms (r = 0.72) and moderately with externalizing symptoms (r = 0.40); immature defenses showed the strongest bivariate association with BPTs (r = 0.56). Age, gender, internalizing, and externalizing symptoms explained 55.9% of BPT variance, increasing to 61.7% after adding defense styles (ΔR2 = 0.058, p = 0.006, f2 = 0.151). However, none of the individual defense style coefficients remained statistically significant after Holm correction. These findings indicate a modest but statistically significant incremental contribution of defense styles considered jointly, without establishing an independent association for any defense style.