Tissue Damage and Pain - Modelling Cutting Behavior in BPD

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The overall aim of this project is the elucidation of neurobiological mechanisms underlying nonsuicidal self-injury (NSSI) in BPD. In addition to pain processing, aspects of NSSI include tissue damage (the most frequent form of NSSI being cutting), the visual impact of seeing blood, and the perspective of the injury as being self-inflicted rather than other-inflicted. In Study 1 of the first funding period, we investigated the influence of tissue injury on stress regulation, and developed a surrogate stimulus that evoked sensory and affective responses that were very similar to those evoked by tissue injury. This stimulus, a non-invasive mechanical "blade", was matched for pain intensity with an incision stimulus. In Study 2, we compared the effects of the incision stimulus on stress levels in BPD patients, the mechanical blade stimulus, and a sham control stimulus (non-painful touch). Interim analysis has revealed a trend for stronger reduction of stress levels following incision and blade compared to the sham stimulus, and similar time courses of tension reduction for the mechanical blade and for incision. In addition, pilot studies have 1) investigated the influence on tension reduction of the experience of seeing (artificial) blood in addition to experiencing pain, and 2) used MR spectroscopy to quantify glutamate and GABA levels in pain-processing brain regions. As the blade stimulus showed both pain-characteristics and stress-regulation properties that were very similar to those induced by incision, it will be used in the studies of the second funding period, which has two major objectives. First, we aim to further elucidate neurochemical and neurofunctional mechanisms related to antinociception in BPD, using recently established neuroimaging methods. Whole-brain echo-planar sprectroscopic imaging will be used to determine glutamate metabolism in pain-processing regions, and GABA and glutamate levels in the posterior insula will be measured. Pseudo-continuous Arterial Spin Labeling, which allows absolute quantification of blood flow in pain-processing regions following single stimuli, will be conducted before and after blade stimulation. In the second part of the project, patients with current NSSI will be randomized into four groups in order to investigate the stress-regulating effects of seeing artificial blood and of self-application of the pain stimulus vs. application by an investigator.