Borderline personality disorder symptoms as mediational mechanisms linking childhood trauma and nonsuicidal self-injury among women with bulimia nervosa.

OBJECTIVE: Nonsuicidal self-injury (NSSI) frequently co-occurs with eating disorders, especially bulimia nervosa (BN). Theoretical models and empirical evidence show many overlapping risk factors for the onset and maintenance of NSSI and BN. However, among those with BN, it remains unclear what distinguishes those who do versus do not engage in NSSI. The primary objective of the present study was to identify factors predicting NSSI among women with BN. Specifically, we tested four domains of borderline personality disorder as mediators between childhood trauma and NSSI.
METHOD: Using structural equation modeling we tested a parallel mediation model to predict NSSI among women with BN (N = 130). Childhood trauma (measured by the Childhood Trauma Questionnaire at baseline) was the independent variable. The four parallel mediators (measured at baseline via the Diagnostic Interview for Borderlines, Revised) were lifetime negative affect, impulsive actions, atypical cognitions (e.g., odd thinking, unusual perceptual experiences, quasi-psychotic thinking), and interpersonal problems. The dependent variable was instances of NSSI during a subsequent two-week ecological momentary assessment protocol.
RESULTS: Childhood trauma was significantly associated with all four mediators (all p values < .01), but only atypical cognitions predicted NSSI (p = .03). The indirect path from childhood trauma to NSSI, through atypical cognitions was significant (path coefficient = .001, SE < .001, p = .01). DISCUSSION: Among women with BN, childhood trauma was associated with atypical cognitions, which in turn predicted NSSI. Atypical cognitions may be a mechanism for NSSI in this population.