The brains of teenage girls who engage in serious forms of self-harm, including cutting, show features similar to those seen in adults with borderline personality disorder, a severe and hard-to-treat mental illness, a new study has found.

Reduced brain volumes seen in these girls confirms biological – and not just behavioral – changes and should prompt additional efforts to prevent and treat self-inflicted injury, a known risk factor for suicide, said study lead author Theodore Beauchaine, a professor of psychology at The Ohio State University.

This research is the first to highlight physical changes in the brain in teenage girls who harm themselves.

The findings are especially important given recent increases in self-harm in the U.S., which now affects as many as 20 percent of adolescents and is being seen earlier in childhood, Beauchaine said.

“Girls are initiating self-injury at younger and younger ages, many before age 10,” he said.

Cutting and other forms of self-harm often precede suicide, which increased among 10- to 14-year-old girls by 300 percent from 1999 to 2014, according to data from the Centers for Disease Control and Prevention. During that same time, there was a 53 percent increase in suicide in older teen girls and young women. Self-injury also has been linked to later diagnosis of depression and borderline personality disorder.

In adults with borderline personality disorder, structural and functional abnormalities are well-documented in several areas of the brain that help regulate emotions.

But until this research, nobody had looked at the brains of adolescents who engage in self-harm to see if there are similar changes.

The new study, which appears in the journal Development and Psychopathology, included 20 teenage girls with a history of severe self-injury and 20 girls with no history of self-harm. Each girl underwent magnetic resonance imaging of her brain. When the researchers compared overall brain volumes of the 20 self-injuring girls with those in the control group, they found clear decreases in volume in parts of the brain called the insular cortex and inferior frontal gyrus.

These regions, which are next to one another, are two of several areas where brain volumes are smaller in adults with borderline personality disorder, or BPD, which, like cutting and other forms of self-harm, is more common among females. Brain volume losses are also well-documented in people who’ve undergone abuse, neglect and trauma, Beauchaine said.

The study also found a correlation between brain volume and the girls’ self-reported levels of emotion dysregulation, which were gathered during interviews prior to the brain scans.