Although some evidence suggests that borderline personality disorder (BPD) is primarily a disorder of the emotion regulation system, findings remain inconsistent. One potential explanation for this is the moderating role of dissociation.

In this study, 33 female subjects with BPD and 26 healthy controls (HC; matched by education level and nicotine intake) were presented idiographic aversive, standard unpleasant and neutral scripts. Modulation of startle reflex and electrodermal responses (skin conductance level; SCL) were measured during imagery of emotional and neutral scripts. Additionally, self-reports of emotional experience (valence and arousal) and present-state dissociation were assessed.

Patients with BPD showed elevated levels of dissociative experiences during testing. Present-state dissociation mediated group differences in SCL and startle response between the HC and BPD groups.

These results suggest that careful attention must be paid to the moderating effect of dissociative symptoms on the psychophysiological responses of BPD patients. Furthermore, the findings have important implications for the assessment and treatment of BPD, including the need to carefully assess BPD patients for dissociative symptoms and to incorporate the treatment of dissociation.