Study identified brain anomalies in pain modulation in self-injurers

Researchers at Sweden’s Karolinska Institute believe they have discovered why self-injurers experience less pain than others. The solution appears to be a more effective pain-modulation mechanism, a breakthrough that can aid people seeking therapy for self-harm.

The outcomes of the study were reported in the journal Molecular Psychiatry. Most people desire to avoid pain, but some people, particularly teens and young adults, can accidentally inflict bodily injury. Although self-harm is frequently connected to other mental health illnesses such as anxiety and depression, not everyone suffering from such a disease engages in self-harm.

“We’ve long attempted to understand how persons who self-injure differ from others and why pain alone isn’t a sufficient deterrent,” says Karin Jensen, researcher and group head at Karolinska Institutet’s Department of Clinical Neuroscience and the study’s corresponding author. “Previous research has shown that persons who self-harm are less sensitive to pain in general, although the reasons underlying this are not entirely understood.”

The current study compared pain modulation in 41 women who had participated in self-injury at least five times in the previous year to 40 matched women who had not engaged in self-injury behaviour.

The women, aged 18 to 35, were subjected to laboratory pain tests at Karolinska University Hospital twice in 2019-2020, during which they were asked to assess the pain they felt from transitory pressure and heat stimulations. MRI scans were also used to examine their brain activity during pain.

The researchers discovered that self-harming women withstood more pain than controls on average. Brain scans indicated changes in activity across the groups as well. When compared to controls, the brain activity of women who self-injure showed stronger connections between brain regions directly engaged in pain perception and those connected to pain regulation.

Another result was that the difference in pain modulation was unrelated to how long, how frequently, or in what way the subjects participated in self-injury.

“Our findings show that efficient pain modulation is a risk factor for self-injury behaviour,” says Maria Lalouni, a researcher at Karolinska Institutet’s Department of Clinical Neuroscience and the study’s joint first author with Jens Fust, who just completed his PhD on the subject. “It also informs us more about the variations in the brains of people who self-injure, knowledge that can be utilised to improve the support offered to persons seeking care for their behaviour, as well as dialogues with patients to help them comprehend their self-injury and the need for treatment.”

The study’s limitations include the fact that women who self-injure reported greater mental comorbidities than controls. They also used more medicines, such as antidepressants, which the researchers took into account.