Neurobiology and genetics of borderline personality disorder

The neurobiological research that has been the most useful in shedding light on the physiology underlying BPD has examined simpler dimensions of behavior separately, including impulsive aggression and affective instability. Evidence suggests impulsive aggression involves a deficit in serotonergic activity. However, the specific mechanism underlying this remains unknown. It is clear this component of behavior is substantially genetically encoded, and therefore new research has focused on elucidating the specific receptors underlying impulsive aggression through the examination of genes coding for specific receptors. Additional research has focused on the brain regions that underlie aggression, and it is likely that the prefrontal orbital frontal cortex exerts an inhibitory control over aggressive behavior in normal individuals. These regions may be underactive in individuals with impulsive aggression and specifically may not be recruited in these patients in response to a serotonergic activation. Less is understood about the physiology of affective instability in personality disorders, but emerging information suggests it is quite different from the affective instability in primary affective disorder. Preliminary evidence implicates the cholinergic system in the control of affective instability, but more research is required to confirm this. Further elucidation of the physiology of impulsive aggression and affective instability may provide more specific targets in the future for the pharmacologic management of these components of BPD.