Somatosensory processing and borderline personality disorder: pain perception and a signal detection analysis of proprioception and exteroceptive sensitivity.

Approximately two thirds of those with borderline personality disorder (BPD) who self-injure report diminished sensitivity to pain during acts of self-harm. Research on pain perception suggests that abnormalities of the motivational-affective domain likely contribute to the commonly reported hypo-analgesia evidenced in BPD. It is not that BPD individuals cannot detect or feel painful stimuli, rather their response to it seems to reflect differences in tolerance and willingness to report a stimulus as painful. Although specific processes involved with pain insensitivity have been debated in literature, the likelihood of generalized dysfunction in the somatosensory systems in BPD has not been considered. Prior BPD research has focused only on the pain submodality of somatosensation. This study assessed pain perception (nociception), basic touch (exteroception), and body sense (proprioception) somatosensory submodalities, in an effort to determine if generalized somatosensory deficits are present in BPD. Subjects diagnosed with DSM-IV BPD (n = 27) were compared with individuals who had a history of major depressive disorder with no current psychopathology (n = 20), and normal controls (n = 44), all drawn from a community setting. Individuals with BPD evidenced higher pain endurance and tolerance, but did not demonstrate generalized somatosensory deficits, as evidenced by appropriate functioning on tasks of exteroceptive and proprioceptive sensitivity. Findings are consistent with (but do not prove) a specific dysfunction in the pain-specific mechanism of sensitivity and perception in BPD, perhaps one that does not disturb the other somatosensory modalities. These data help to provide a firmer empirical basis for pain insensitivity as an endophenotype for BPD.