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New work by ���߲ݴ�ý Scarborough researchers gives the best description yet of the neural circuits that underlie a severe mental illness called borderline personality disorder (BPD), and could lead to better treatments and diagnosis.

The work shows that brain regions that process negative emotions (for example, anger and sadness) are overactive in people with BPD, while brain regions that would normally help damp down negative emotions are underactive.

People with BPD tend to have unstable and turbulent emotions which can lead to chaotic relationships with others, and which put them at higher risk than average for suicide. A number of brain imaging studies have found differences in the function of brains of people with BPD, but some of the studies have been contradictory.

A team led by Anthony C. Ruocco, assistant professor in the Department of Psychology and program in neuroscience, analyzed data from 11 previously published studies and confirmed a number of important differences between people with BPD and those without.

On the one hand, a brain area called the insula – which helps determine how intensely we experience negative emotions – is hyperactive in people with BPD. On the other hand, regions in the frontal part of the brain – which are thought to help us control our emotional reactions – are underactive.

“It’s not just that they have too much drive from their emotions,” Ruocco says. “They seem to have less of the ‘brakes’ to try to curb those emotions and to help regulate their intensity.”

The findings fit well with symptoms seen in people with BPD, Ruocco says.

“The hallmark symptom that people describe is emotion dysregulation -- you're happy one moment, and the next moment you're feeling angry or sad or depressed. People with BPD can cycle through emotions, usually negative ones, quite rapidly.”

More important is how the findings might be useful in diagnosis and treatment. One challenge is that BPD often occurs with other disorders, such as major depression, which can make it harder to identify and treat.

The new results raise the possibility that brain imaging could be used to make a more definitive diagnosis of BPD. In the future it might also help determine what treatments are most likely to be effective for an individual patient, based on what the imaging studies show about their brain function before they even begin treatment, Ruocco says.

The results are published in the journal Biological Psychiatry.