ABSTRACT: Background:Studies on adults suggest that the presence of comorbid depression and Borderline Personality Disorder (BPD) is associated with an elevated risk of self-harming behaviours and that self-harming behaviours, when present, will have higher severity. This comorbidity, furthermore, complicates clinical assessments, which may be an obstacle to early identification and proper intervention. Adolescents who self-harm frequently report high levels of depressive symptoms, but this is often not reflected in the clinicians' assessment. BPD is still a controversial diagnosis in young people, and less is known about the clinical significance of comorbid BPD in adolescent populations.The purpose of the present study was to examine the impact of BPD on the assessment and course of self-reported and clinician-rated depression in self-harming adolescents before and after a treatment period of 19 weeks. We hypothesized that, compared to adolescents without BPD, adolescents with BPD would self-report higher levels of depression at baseline, and that they would have less reduction in depressive symptoms. Methods:A total of 39 adolescents with depressive disorders and BPD-traits participating in a randomised controlled trial on treatment of self-harm with Dialectical Behaviour Therapy adapted for Adolescents or enhanced usual care were included. Adolescents with full-syndrome BPD (n = 10) were compared with adolescents with sub-threshold BPD (n = 29) with respect to their self-reported and clinician-rated depressive symptoms, suicidal ideation and global level of functioning at baseline, and after 19 weeks of treatment (end of trial period). Results:At baseline, adolescents with full-syndrome BPD self-reported significantly higher levels of depressive symptoms and suicidal ideation compared to adolescents with sub-threshold BPD, whereas the two groups were rated as equally depressed by the clinicians. At trial completion, all participants had a significant reduction in suicidal ideation, however, adolescents with BPD had a poorer treatment outcome in terms of significantly higher levels of clinician-rated and self-reported depressive symptoms and significantly lower levels of global functioning. At baseline as well as at trial completion, self-reported and clinician-rated levels of depressive symptoms were not significantly correlated in adolescents with BPD. In a multiple linear regression analysis, a diagnosis of BPD and a high baseline level of clinician-rated depressive symptoms predicted higher levels of depressive symptoms at trial completion, whereas receiving Dialectical Behaviour Therapy predicted lower levels of depressive symptoms. Conclusion:Our findings suggest that a diagnosis of BPD may have a strong impact on the assessment and course of depressive symptoms in self-harming adolescents. Although rated as equally depressed, adolescents with BPD self-reported significantly higher levels of depressive symptoms and suicidal ideation at baseline, and showed a poorer outcome in terms of higher levels of depressive symptoms and lower levels of global functioning at trial completion compared to adolescents with sub-threshold BPD. Our findings suggest that receiving Dialectical Behaviour Therapy could lead to a greater reduction in depressive symptoms, although firm conclusions cannot be drawn given the limited sample size.Clinicians should be aware of the possibility of underestimating the severity of depression in the context of emotional and behavioral dysregulation. Providing BPD specific treatments seems to be important to achieve sufficient treatment response with regard to depressive symptoms in adolescents with BPD-traits. Trial registration:Treatment for Adolescents With Deliberate Self Harm; NCT00675129, registered May 2008.
