EEG theta activity and pain insensitivity in self-injurious borderline patients

The principal aim of this study was to investigate possible neurophysiological underpinnings of self-injurious behavior in women with borderline personality disorder (BPD). Pain report and EEG power spectrum density during a laboratory pain procedure, a 4-min 10 degrees C cold pressor test (CPT), were compared among four groups; female inpatients with BPD who do (BPD-P group, n = 22) and do not (BPD-NP group, n = 19) report pain during self-injury, female inpatients with major depression (n = 15), and normal women (n = 20). The BPD-NP group reported less pain intensity during the CPT compared to the other groups. Total absolute theta power was significantly higher in the BPD-NP group compared to the Depressed (P = 0.0074) and Normal (P = 0.0001) groups, with a trend toward being significantly higher compared to the BPD-P group (P = 0.0936). Dissociative Experience Scale scores were significantly higher in the BPD-NP group compared to the Depressed and Normal groups (maximum P = 0.0004), and significantly higher in the BPD-P group compared to the Normal group (P = 0.0016). Beck Depression Inventory and Sheehan Patient Rated Anxiety Scale scores were significantly lower in the Normal group compared to all patient groups. Theta activity was significantly correlated with pain rating (Pearson partial r = -0.43, P = 0.0001) and Dissociative Experiences Scale score (Pearson partial r = 0.32, P = 0.01).