Psychiatric comorbidity in hospitalized adolescents with borderline personality disorder.

Objective: The goal of this study was to carry out the first comprehensive assessment of psychiatric comorbidity in adolescents (aged 12-17 years) with DSM-IV criteria for borderline personality disorder (BPD) compared to a psychiatric comparison group without BPD. Complex comorbidity (a hallmark feature of adult BPD and defined as having any mood or anxiety disorder plus a disorder of impulsivity) was also examined as a distinguishing feature of adolescent BPD.

Method: Consecutively admitted patients (October 2008 to October 2012) to an inpatient psychiatric hospital received parental consent and gave assent for participation in the study (N = 418), with the final sample after exclusions consisting of 335 adolescent inpatients. A comprehensive, multimethod approach to determining psychiatric comorbidity was used, including both an interview-based (categorical) and a questionnaire-based (dimensional) assessment as well as both parent and adolescent self-report. Measures included the Diagnostic Interview Schedule for Children (NIMH-DISC-IV), Child Behavior Checklist (CBCL), Youth Self-Report (YSR), Car, Relax Alone, Forget, Friends, Trouble (CRAFFT), and the Childhood Interview for DSM-IV Borderline Personality Disorder (CI-BPD).

Results: Thirty-three percent of the final sample met criteria for BPD. Adolescent inpatients with BPD showed significantly higher rates of psychiatric comorbidity compared to non-BPD psychiatric subjects for both internalizing (χ²₁ = 27.40, P < .001) and externalizing (χ²₁ = 19.02, P < .001) diagnosis. Similarly, using dimensional scores for self-reported symptoms, adolescent inpatients with BPD had significantly higher rates of psychiatric comorbidity compared to non-BPD subjects for internalizing (t₃₂₉ = -6.63, P < .001) and externalizing (t₃₂₉ = -7.14, P < .001) problems. Parent-reported symptoms were significantly higher in the BPD group only when using a dimensional approach (internalizing: t₃₂₁ = -3.42, P < .001; externalizing: t₃₂₁ = -3.32, P < .001). Furthermore, significantly higher rates of complex comorbidity were found for adolescents with BPD (χ²₁ = 26.60, P < .001). Moreover, externalizing and internalizing problems interacted in association with borderline traits (B = .25; P < .001).

Conclusions: Similar to findings in adult studies of BPD, adolescents with BPD demonstrate significantly more complex comorbidity compared to psychiatric subjects without BPD.