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This post was written by Annemarie Miano and Eric A. Fertuck.
Self-inflicted physical pain is common in borderline personality disorder (BPD). This often takes the form of self-cutting, burning, and self-hitting. Upon learning this, most people unfamiliar with BPD are confused and concerned. "Why would anyone deliberately physically harm themselves?" they often think. The cause of deliberate self-harm is one of the most important scientific enigmas for BPD researchers.
Here is some of what we know. Self-injury is frequently used after social rejection in BPD. Those with BPD use self-harm predominantly to diminish aversive and painful emotions or to "self-punish." Interestingly, people with BPD appear to have attenuated pain perception, and clinical reports suggest relief from emotional pain following self-injury.
In an important new article in the American Journal of Psychiatry, prominent BPD researchers Drs. Barbara Stanley (Columbia Psychiatry) and Larry Siever (Mt. Sinai School of Medicine) introduce a compelling new model of BPD that attempts to explain the links between self-injurious behavior and interpersonal difficulties in BPD (Dr. Stanley is a colleague and mentor of mine). Their framework also aims to elucidate the unstable relationships, the chronic feeling of emptiness, the suspiciousness of others, and the intense concern and anxiety over the emotional availability and support of romantic partners, friends, and family.
The Stanley and Siever model highlights the role of three types of neuropeptides in BPD symptoms: opioids, oxytocin, and vasopressin. Neuropeptides are molecules in the human body that transmit information between nerve cells called neurons. Each neuropeptide has neuron targets in different bodily organs, such as the brain, where they function and exert unique effects on behavior, thoughts, and feelings.
Opioids are the natural painkillers of our bodies. This holds not only for physical pain but also for emotional pain, such as what is associated with feeling hurt after being rejected by someone you care about. In BPD, Stanley and Siever posit that opioids play a common role in the experience of negative emotions and self-injurious behavior.
For example, some research indicates that BPD patients have low baseline opioid levels. However, they also appear to have an increased number and more receptors for opioids in the brain. The opioid release that is triggered when pain is encountered might, therefore, powerfully affect those with BPD. Opioid release after self-injurious behavior might explain the relief from the emptiness individuals with BPD experience.
Oxytocin, another neuropeptide, plays an important role in the bonding that takes place between infant children and their parents, engenders trust in relationships, and influences other prosocial behaviors. Oxytocin levels during early pregnancy and the postpartum period are associated with bonding behaviors such as touching, frequent monitoring, and vocalization. Furthermore, in healthy volunteers, oxytocin is associated with feeling trust towards others, accepting social risks, and empathizing with others. In fact, if you have read prior blog posts about performance on the Reading the Mind in the Eyes Test, you know the capacity to appraise the mental states of others is associated with increased oxytocin.
The last neuropeptide that might be involved in the interpersonal disturbances of BPD, vasopressin, is associated with aggressive behavior in social contexts. For example, if vasopressin is inhaled, neutral stimuli may seem more threatening. Since one characteristic of BPD is having a lowered threshold for aggression and anger, it can be hypothesized that they have a heightened vasopressin level, leading to their emotional instability and easily triggered aggression towards others.
In summary, neuropeptides may represent several important pieces of the puzzle that is BPD. In particular, neuropeptides may underlie some of the troubling interpersonal difficulties and self-injurious behaviors so common in this disorder. Research in this area is in its infancy, but it may lead to better understanding and treatment for BPD, both in the form of medications and psychotherapy.
