The possible existence of diminished pain sensitivity in borderline personality disorder (BPD) is of major theoretical interest given the well-known proclivity of some patients with BPD for frequent self-mutilating behaviors, such as repeated cutting and burning of the skin. Schmahl et al1 recently reported that, relative to healthy controls, patients with BPD exhibited higher pain thresholds, which the authors claim is linked to diminished activation in several brain areas, as reflected in functional magnetic resonance imaging (fMRI) measures. Unfortunately, the psychophysical task used by Schmahl et al1 to assess pain sensitivity may reflect across-group differences in either sensory-discriminative or affective-motivational factors, with aspects of the reported results actually favoring the latter, response criterion,2- 4 type of difference. In addition, their interpretation of the neuroimaging data hinges on an assumed equality, but an actual inequality, in the pain measures.
Lenzenweger MF, Pastore RE. On Determining Sensitivity to Pain in Borderline Personality Disorder. Arch Gen Psychiatry. 2007;64(6):747–748. doi:10.1001/archpsyc.64.6.747