Approximately 70–80% of women meeting criteria for borderline personality disorder (BPD) report attenuated pain perception or analgesia during non-suicidal, intentional self-mutilation. The aim of this study was to use laser-evoked potentials (LEPs) and psychophysical methods to differentiate the factors that may underlie this analgesic state. Ten unmedicated female patients with BPD (according to DSM-IV) and 14 healthy female control subjects were investigated using brief radiant heat pulses generated by a thulium laser and five-channel LEP recording. Heat pulses were applied as part of a spatial discrimination task (two levels of difficulty) and during a mental arithmetic task. BPD patients had significantly higher heat pain thresholds (23%) and lower pain ratings (67%) than control subjects. Nevertheless, LEP amplitudes were either normal (N1, P2, P3) or moderately enhanced in BPD patients (N2). LEP latencies and task performance did not differ between patients and control subjects. The P3 amplitudes, the vertex potential (N2–P2), and the N1, which is generated near the secondary somatosensory cortex, were significantly reduced during distraction by mental arithmetic in both groups. In addition, P3 amplitudes reflected task difficulty. This study confirms previous findings of attenuated pain perception in BPD. Normal nociceptive discrimination task performance, normal LEPs, and normal P3 potentials indicate that this attenuation is neither related to a general impairment of the sensory-discriminative component of pain, nor to hyperactive descending inhibition, nor to attention deficits. These findings suggest that hypoalgesia in BPD may primarily be due to altered intracortical processing similar to certain meditative states.
aInstitute of Physiology and Pathophysiology, Johannes Gutenberg-University, Saarstr. 21, D-55099 Mainz, Germany
bDepartment of Neurology, Johannes Gutenberg-University, Langenbeckstr. 1, D-55101 Mainz, Germany
cDepartment of Psychosomatic Medicine and Psychotherapy, Central Institute of Mental Health, J 5, D-68159 Mannheim, Germany
dDepartment of Psychiatry and Psychotherapy, University of Freiburg Medical School, Hauptstr. 5, D-79104 Freiburg, Germany
∗Corresponding author. Tel.: +49-621-1703-171; fax: +49-621-1703-172
1Both authors contributed equally to this work.
Submitted September 8, 2003; revised April 16, 2004; accepted April 26, 2004.