Neural circuits foster oversensitivity: borderline personality patients activate brain in specific ways.

People diagnosed with the mental ailment known as borderline personality disorder hemorrhage emotion. Real or perceived rejections, losses or even minor slights trigger depression and other volatile reactions that can lead to suicide.

New brain-imaging research suggests that in such people specific neural circuits foster extreme emotional oversensitivity and an inability to see other people as having both positive and negative qualities.

Psychiatrist Harold Koenigsberg of Mount Sinai School of Medicine in New York City described his team's results January 17 in New York City at a meeting of the American Psychoanalytic Association.

"I suspect that in social situations, people with this disorder activate the brain in unique ways," Koenigsberg says.

The findings unveil brain networks that may underlie the "faultybrakes" that borderline personality patients attempt to apply to their emotional reactions, remarks psychiatrist John Oldham of Baylor College of Medicine in Houston.

Borderline personality disorder affects one in five psychiatric patients, says Koenigsberg. It most often affects women, especially those who are depressed, and men who display violent and criminal tendencies classed as antisocial personality disorder. About one in 10 people with borderline disorder commits suicide.

Koenigsberg's group first tested 19 adults with borderline personality disorder and 17 others with no serious psychiatric conditions. While in an fMRI scanner, participants viewed five pleasant images--such as a laughing man playing with two children--and five disturbing images, including a man assaulting a young woman.

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Whether the images were pleasant or disturbing, borderline personality disorder patients displayed heightened blood flow--a marker of neural activity--in the brain's chief visual area and in the amygdala, a key structure in emotion regulation. This finding fits with earlier evidence that borderline personality disorder patients detect brief facial emotional expressions that emotionally healthy people typically do not notice.

In a second experiment, 18 borderline personality disorder patients and 16 healthy volunteers viewed a series of neutral images and disturbing images. In some trials, participants simply looked at the images; in others, participants tried to assume the role of a detached observer.

As detached observers of disturbing scenes, emotionally healthy participants displayed pronounced activity in brain areas implicated in regulating attention and resolving conflicts. Borderline personality disorder patients showed almost no activity in those brain regions when trying to take a detached perspective.

Most people have the ability to perceive both favorable and negative aspects of a person, helpful in resolving conflict. Lacking this skill, borderline patients end up veering back and forth between regarding those they know as either wonderful or awful, Koenigsberg suggests.