Researchers at Sweden’s Karolinska Institutet may have discovered an explanation for why self-injurers typically experience less pain than others. A better pain-modulation system appears to be the solution, a finding that can help those who are seeking care for self-harm. The results are presented in the Molecular Psychiatry journal.
While most people make an effort to avoid suffering, some, particularly teenagers and young adults, occasionally put themselves at risk of physical harm. Although self-injury is significantly correlated with other mental health conditions including anxiety and depression, not everyone with these conditions actually self-harms.
“We have long tried to understand how people who display self-injury behaviour differ from others and why the pain itself isn’t a sufficient deterrent,” says Karin Jensen, researcher and group leader at the Department of Clinical Neuroscience, Karolinska Institutet, and the study’s corresponding author. “Previous studies how shown that people who self-harm are generally less sensitive to pain, but the mechanisms behind it are not fully understood.”
Self-injurious behavior (SIB) is the act of engaging in activity that has the potential to cause bodily harm to one’s own body. SIB is demonstrated by 10 to 15 percent of individuals with intellectual disability.
SIB frequently manifests itself in head-hitting, head-banging, and self-biting, among other behaviors. SIB can cause less serious wounds like scrapes and bruises or more serious wounds like blindness, fractured bones, or even death.
Our study suggests that effective pain modulation is a risk factor for self-injury behaviour. It also tells us more about differences in the brains of people who engage in self-injury, knowledge that can be used for improving the support provided to people seeking care for their behaviour as well as in conversations with patients to help them understand their self-injury and the need for treatment.
Maria Lalouni
Tolerated more pain
In the current study, the researchers compared the pain modulation of 40 matched women without self-injury behavior with that of 41 women who had self-injured at least five times in the previous year in order to evaluate these processes.
The women, who ranged in age from 18 to 35, had two laboratory pain tests at Karolinska University Hospital in 2019–2020, where they were prompted to rate the level of discomfort they felt in response to brief pressure and heat stimulations.
Using MRI scans, their brain activity during pain was also determined. Researchers discovered that on average, self-harming women could take more pain than non-harming women. The brain scans also showed that the groups’ activations were different from one another.
There are many different reasons why someone might commit self-harm. For instance, self-harming can get you attention or access to a favorite toy or pastime. Self-harm can also be used as an escape from or avoidance of unpleasant tasks, such as academic expectations or daily tasks like cleaning one’s teeth.
Similar to how someone might press on their head or eyes to momentarily lessen discomfort when they have a headache, SIB may also happen because it gives sensory information to a part of the body or eases pain. Self-injury has been successfully treated using behavioral therapies.
The brain activity of the women who self-harmed showed greater connections between brain regions directly connected to the sense of pain and those linked to its regulation than did the controls.
Another conclusion was that the duration, frequency, or mode of the subjects’ self-injury did not affect the differences in pain modulation.
Clinically useful knowledge
“Our study suggests that effective pain modulation is a risk factor for self-injury behaviour,” says Maria Lalouni, researcher at the Department of Clinical Neuroscience, Karolinska Institutet, and the study’s joint first author with Jens Fust, who recently earned his PhD on the project.
“It also tells us more about differences in the brains of people who engage in self-injury, knowledge that can be used for improving the support provided to people seeking care for their behaviour as well as in conversations with patients to help them understand their self-injury and the need for treatment.”
The fact that women who engaged in self-injury behavior tended to report more psychiatric comorbidities than controls is one of the study’s limitations. In their analyses, the researchers took into account the fact that they also consumed more medications, such as antidepressants.
The Swedish Research Council, Karolinska Institutet’s Strategic Research Area Neuroscience (StratNeuro), and Leif Lundblad’s gift to pain research all provided grants for the study.
