Sub-threshold or full-syndrome borderline personality disorder in adolescents with recurrent self-harm – distinctly or dimensionally different?

Background Borderline personality disorder (BPD) is a severe mental disorder frequently seen in individuals with recurrent self-harm behaviour. To what extent there are distinguishing characteristics between self-harming adolescents who meet the criteria for a full diagnosis of BPD, a sub-threshold number of BPD criteria and those who don’t have BPD, with respect to clinical characteristics, is still uncertain and could have important clinical implications. Methods Data from 103 adolescents with recurrent self-harm behaviour recruited from child and adolescent psychiatric outpatient clinics were collected through clinical interviews and self-reports. Bivariate analyses comparing participants with or without a diagnosis of BPD were performed. Group differences based on the number of BPD criteria fulfilled (few-if-any BPD: 0–2 criteria, sub-threshold BPD: 3–4 criteria, full-syndrome BPD: 5 or more criteria) were tested and regression analyses performed. Results Adolescents with a diagnosis of BPD (28.2%) had significantly higher numbers of co-morbid DSM-5 disorders, suicide attempts and self-harm methods. They also reported significantly higher levels of suicidal ideation, depression, anxiety and impulsivity, compared with adolescents without BPD. Adolescents with sub-threshold BPD (20.4%) place themselves in the intermediate position between participants with full-syndrome BPD and participants with few-if-any BPD, in terms of these symptoms. Higher levels of emotional regulation difficulties and a lower level of global functioning were significantly associated with fulfilling a higher number of BPD criteria. Conclusion Adolescents with recurrent self-harm who meet diagnostic criteria for a full-syndrome BPD or sub-threshold BPD seem to have difficulties within the same spectrum. They seem dimensionally, but not categorically, different with respect to the severity of their difficulties. These adolescents need interventions aimed at their dysfunctional self-harm behaviour, emotional regulation difficulties and BPD symptoms at an earlier, rather than at a later stage of symptom development.