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Biology plays key role in borderline personality. (A Genetic 'Template').

NEW YORK -- Biology plays a key role in the evolution of borderline personality disorder. Alterations in brain chemistry and physiology, to a great extent genetically determined, apparently create predispositions that lead to characteristic problem behaviors, Dr. Larry J. Siever said at a conference on borderline personality disorder sponsored by Columbia University.

"Genetics provides the template around which personality coalesces," said Dr. Siever, professor of psychiatry at Mount Sinai School of Medicine, New York.

It has become increasingly evident that the traditional distinction between Axis I disorders as "biological" and Axis II as "psychological" is simplistic and that considerable overlap exists between them. Vulnerability to personality disorders (as, perhaps, to schizophrenia and bipolar disorder) is "patterned by biological factors and shaped by the environment," he said.

The characteristic behaviors of borderline personality evolve, in this view, to forestall unbearable dread, despair, and fear of abandonment. And these feelings, in turn, have biologic underpinnings.

In trying to make sense of and cope with intense impulses and affects, a child may develop behaviors that seem maladaptive to others, but essential to survival for them. The apparent manipulativeness of a borderline individual, for example, may represent a desperate attempt to maintain self-esteem, which requires other people to behave in a certain way, Dr. Siever said.

Early environmental influences--parental depression or abuse--can mold these vulnerabilities into a traumatized personality that manifests itself in even more disturbed interpersonal relationships.

"Impulsivity, difficulty in muting aggressive impulses, heightened reactions to disappointment and frustration--these are temperamental factors around which the personality crystallizes," he said at the meeting, which was also sponsored by the National Education Alliance for Borderline Personality Disorder.

The biologic basis of impulsivity has been most studied, and appears to involve reduced activity in serotonergic systems that have an inhibitory function. "We all feel called upon to engage in aggression but are able to modulate it" in a way that borderline patients may not, he suggested.

In one study, the release of prolactin in response to fenfluramine challenge, which is mediated by serotonin, was significantly blunted in 20 borderline patients, compared with 14 healthy controls.

Other research has focused on the orbital prefrontal cortex, a brain area heavy in serotonergic neurons, which serves as "a brake to the emergence of aggression from subcortical regions." In impulsive borderline patients, activation of the prefrontal cortex in response to a serotonin probe is markedly less than in controls, Dr. Siever said.

Serotonin transporters are reduced in this brain area of impulsive-aggressive borderline patients, and postsynaptic serotonin receptors show increased binding capacity, possibly reflecting an attempt to compensate for relative depletion of the neurotransmitter, he said.

Affective instability--the intense, transient mood shifts that characterize many borderline patients--appears related to hyperresponsivity of the limbic brain. The injection of physostigmine, which increases activity of the neurotransmitter acetylcholine, triggers dysphoric mood in borderline patients but in not normal controls, compared with placebo. The "momentary dread" evoked in patients by this provocation mimics the emotion to which they are subject in real life, he said.
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Author:Sherman, Carl
Publication:Clinical Psychiatry News
Date:Dec 1, 2002
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