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Borderline Personality Disorder Linked to Brain Abnormality by Novel Scan
> 12/28/2007 11:30:10 AM

Loved ones often despair of ever understanding the inscrutable emotional vortex of Borderline Personality Disorder (BPD). Those with BPD experience rapid shifts in emotion and perspective that lead to rash relationship decisions and impulsive career moves. Their lack of impulse control is particularly apparent in situations with negative emotional significance, sometimes leading to extreme expressions of anger or disappointment over objectively minor setbacks. These outbursts have been difficult to understand and predict, but a study in the most recent edition of the American Journal of Psychiatry uncovered a neurological basis for the problem.

Dr. David Silbersweig compared 16 subjects with BPD to a control group in a go/no-go task, a task in which subjects must hit a button when a stimulus fits into the right category and resist the impulse to hit it when the rules of the game require them to desist. For this experiment, the stimuli were words with obvious semantic categories and seemingly irrelevant emotional connotations. While the subjects were instructed to only pay attention to the semantic categories, the researchers focused on the emotional connotations in order to unearth any variability in performance for positive, neutral, and negative words. They found that subjects with BPD performed marginally worse overall, but the more interesting observation was that their impulse control was significantly impaired for negative words.

With a reliable way to induce a failure in impulse control, Dr. Silbersweig moved to scan the brains of BPD subjects during the go/no-go task. However, the region of the brain that he suspected of causing the failure, the ventromedial prefrontal cortex, is extremely difficult for fMRI machines to read because of signal interference. Not one to shy away from a problem, he built a special fMRI activation probe to boost accuracy. The resulting images confirmed that the ventromedial prefrontal cortex does not activate properly in BPD brains exposed to negative stimuli.

An editorial in the same journal issue praises the clever design of Dr. Silbersweig's experiment and expresses confidence that his findings will lead to practical treatments. Certainly, it will be much easier to evaluate the effectiveness of new drugs and therapies if doctors have a way to quantify neural symptoms and thus gauge recovery without relying on subjective reports or behavioral tests. In addition, the identification of a specific neural defect may help dispel the mystery surrounding the erratic actions of those with BPD. These results allow us to see BPD as a complex interaction of excessive emotions and impaired constraint, a combination that leaves the BPD brain most unable to control itself just at the moment when control is most important.

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