Brain trace of personality disorder found

HOUSTON, Aug. 11 (UPI) -- U.S. and British scientists say they've identified a specific difference in brain function in those with borderline personality disorder.

People with the disorder are impulsive, and have unstable interpersonal relationships, self-image and emotional responses, the scientists said, noting about 2 percent of the general population has the affliction.

The study led by Baylor College of Medicine Assistant Professor Brooks King-Casas enrolled 55 people with the personality disorder to play a game with 55 normal people. One player in each game was designated the "investor," and the other, the "trustee." Each investor sent $20 to the trustee, the investment is tripled and the trustee must decide how much to return to the investor.

Blood flow in the brain of all players was measured during the game. Of particular interest to researchers was activity in the anterior insula area of the brain, known to respond when social norms are being considered.

In those without the disorder the scientists noted activity in the anterior insula was directly proportional to the amount of money sent and received. However, the area showed activity in those with the disorder only when they sent money, not when they received it.

The study appears in the journal Science.