Identity disturbance and substance-dependence in patients with borderline personality disorder

Identity disturbance is one of the DSM-IV criteria for borderline personality disorder, but there has been little attention to its nature. Four subsets of identity disturbance (role absorption, painful incoherence, inconsistency and lack of commitment) have been assessed. This study aimed to assess the role of these subsets in patients with borderline personality disorder and to examine the relationship between identity disturbances and substance-dependence.

This case-control study was conducted on 40 patients with borderline personality disorder who were referred to Shahid Beheshti Hospital in Kerman from 2004 to 2005 and 40 healthy people who were matched with the case group in term of gender and educational level. Data gathering was carried out with three questionnaires including a demographic-related questionnaire, disturbance questionnaire (including 35 items) and a questionnaire related to substance-dependence and its related factors. Statistical analysis was performed using SPSS 11 for Windows, t test and ANOVA.

The mean score of 33 items of the identity disturbance questionnaire were greater with significant difference in the case group (P<0.05). The means differences in the two groups in all subsets were statistically significant, except for role absorption (P<0.05). The means differences in all subsets in substance-dependent and substance-independent subjects in both groups were not significant statistically. The most common substance-dependence in both groups was related to cigarette smoking and cannabis. Opium and cannabis dependence was significantly greater in patients with borderline personality disorder.

Identity disturbance is one of the major criteria for borderline personality disorder, but in different societies the role of its subsets are different. On the other hand, assessing subsets of identity disturbance has no value in assessing substance-dependence in patients with borderline personality disorder.