Dr. Grossi's Blog
Borderline personality disorder is characterized by unstable interpersonal relationships, emotional dysregulation, and impaired impulse control. It extracts a substantial toll on those afflicted, their social sphere, and on the health care system. Their interpersonal behavior is ofter volatile and unpredictable leaving others confused and angry.
King-Casas et.al. studied individuals with this problem using an economic exchange game and neuroimaging. The economic game is multiround, involves an exchange of money between an investor who decides how much money to commit and a trustee who decides how much of the investment, which is tripled in the game, to return to the investor. They both end up better is they cooperate but that requires that they trust one another. This trust is built up by repeated fair offers during the game. If the investor does not trust, he/she will not invest. This is the finding at the end of games where the trustee has borderline personality suggesting that they were less likely to establish cooperative relationships. Investment remained high at the end of games where the trustee was healthy. Healthy trustees used a coaxing approach more than twice as often the borderline trustees. In this approach, generous returns were given investors over a period thus building trust.
To find the neuroanatomical/neurophysiological underpinnings of this phenomena the researchers used neuroimaging to study brain activation of trustees in response to a task, viz. an investor offering a small investment, a sign of mistrust. The brain response in healthy and borderline trustees was different in one brain area, the anterior insula. In health players, small investments correlated with large activation and large investments correlated with small activation. In borderline trustees there was no difference in activation with offer size. Furthermore, in healthy controls the anterior insula was activated in response to distrustful offers from investors as well as stingy repayments. In borderline players neural activity only occurred when repaying. Therefore the borderline individual had selective impairment in representing the other. These findings fit in nicely with what is the most effective treatment for borderline personality, dialectical behavior therapy DBT). The core assumption of this therapy is that borderline patients lack personal self-regulation in interpersonal relations.