BACKGROUND: Depression and borderline personality disorder (BPD) are highly comorbid conditions that are both associated with nonsuicidal self-injury (NSSI). AIMS: The purpose of this study was to determine if depression is associated with NSSI after controlling for BPD traits. A distinction was made between NSSI for emotional regulation and NSSI for interpersonal motives.
METHOD: Logistic regression analyses were conducted on cross-sectional data from a general population sample of 7370 adults who completed the 2007 Adult Psychiatric Morbidity Survey. Depressive symptoms were assessed with the revised Clinical Interview Schedule. NSSI and motives for NSSI were also assessed during clinical interviews. BPD traits were assessed with the participant-completed Structured Clinical Interview for DSM-IV Axis II Personality Disorders.
RESULTS: Participants in a major depressive episode were more likely to have engaged in emotional-regulation NSSI and interpersonal NSSI than participants without depression. After controlling for BPD traits depression remained associated with emotional-regulation NSSI, whereas the association with interpersonal NSSI became nonsignificant. There were statistically significant relationships between depression and both types of NSSI occurring indirectly through BPD traits.
CONCLUSIONS: BPD traits account for a significant portion of the cross-sectional relationship between depression and past NSSI that varies in size depending on the motive for NSSI. People with depression are more likely to have engaged in NSSI for emotional regulation even in the absence of prominent BPD traits. In contrast, BPD traits may be more prominent in people with depression who have engaged in interpersonal NSSI.