Maladaptive Personality Traits and Internalizing and Externalizing Problems: The Role of Borderline and Narcissistic Features in Adolescence.

Objective: Research has shown the importance of delving into the variables associated with externalizing and internalizing behaviors in adolescence, highlighting gender-related differences in their presentations. This two-wave longitudinal study aims to address gaps in understanding the concurrent contribution of borderline and narcissistic personality traits to the presence and maintenance of internalizing and externalizing problems in adolescence.

Method: We recruited 705 adolescents (65% females; age range 13-19 years old; Mage = 15.84, SD = 1.31) to self-report on behavioral problems (YSR-112), borderline (BPFSC-11) and narcissistic traits (PNI) at baseline and again on behavioral problems after 12 months.

Results: Data highlighted significant differences between males and females for all variables except externalizing problems. Hierarchical regression models showed that borderline traits are a prominent risk factor for all behavioral problems in males and females at baseline and after 12 months. Moreover, regardless of gender, higher grandiose narcissism contributes to lower internalizing problems only when the direct contribution of vulnerable presentations of narcissism is considered. Grandiose narcissism is also a risk factor for externalizing problems after 12 months in females, whereas vulnerable narcissism significantly increases the likelihood of internalizing trajectories improving over 12 months.

Conclusions: This study provides more evidence of the associations between maladaptive personality traits and adolescent internalizing and externalizing problems: (1) confirming that borderline traits are crucial beyond gender, (2) stressing the importance of considering both grandiose and vulnerable narcissistic traits, and (3) highlighting the adaptive value of narcissistic vulnerability in capturing the adolescent crisis. The implications for clinical practice and intervention are also discussed.