Researchers at Karolinska Institutet in Sweden may have found an explanation why people with self-harming behavior generally feel less pain than others. The key appears to be a more efficient pain modulation system, a discovery that may benefit people seeking help for their self-harm. The results are published in the journal Molecular Psychiatry.
Most people try to avoid pain, but some, especially teenagers and young adults, can sometimes physically injure themselves. Self-harm is strongly associated with other mental health issues, such as anxiety and depression, but far from all people with such a condition self-harm.
“We have long tried to understand how people who display self-harming behavior differ from others and why pain itself is not a sufficient deterrent,” says Karin Jensen, researcher and group leader at the Department of Clinical Neurosciences, Karolinska Institutet, and the corresponding author of the study. “Previous studies have shown that people who self-injure are generally less sensitive to pain, but the underlying mechanisms are not fully understood.”
Tolerated more pain
In the current study, researchers examined these mechanisms by comparing pain modulation in 41 women who had self-harmed at least five times in the past year with 40 matched women with no self-harming behavior. The women, aged 18 to 35, underwent laboratory pain tests at Karolinska University Hospital twice in 2019-2020 during which they were asked to rate the pain they felt following transient pressure and heat stimulation. Their brain activity during pain was also measured using MRI.
Researchers found that, on average, women who self-injured tolerated higher levels of pain than controls. Brain scans also revealed differences in activation between the groups. Compared to controls, the brain activity of women with self-injurious behavior showed more connections between brain areas directly involved in pain perception and those related to pain modulation.
Another finding was that the difference in pain modulation was not determined by how long, how often, or how the participants self-injured.
Clinically useful knowledge
“Our study suggests that effective pain modulation is a risk factor for self-injurious behavior,” says Maria Lalouni, researcher in the Department of Clinical Neurosciences, Karolinska Institutet, and co-author of the study with Jens Fust, who recently earned her doctorate on the project. “It also tells us more about the differences in the brains of people who self-harm, knowledge that can be used to improve the support provided to people seeking care for their behavior as well as in conversations with patients to help them. to understand each other – injury and need for treatment.
Limitations of the study include that women with self-injurious behavior tended to report more psychiatric comorbidities than controls. They also took more medications, such as antidepressants, than the researchers factored into their analysis.
The study was supported by grants from the Swedish Research Council and from the Strategic Research Area in Neuroscience (StratNeuro) at the Karolinska Institutet, and a donation from Leif Lundblad to pain research.
Publication: “Increased pain inhibition and increased integration of pain-modulating brain networks in women with self-injurious behavior”, Maria Lalouni*, Jens Fust*, Johan Bjureberg, Gránit Kastrati, Robin Fondberg, Peter Fransson, Nitya Jayaram-Lindström, Eva Kosek, Clara Hellner, Karin B. Jensen, Molecular Psychiatry, online June 13, 2022, doi: 10.1038/s41380-022-01639-y
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