Biological underpinnings of borderline personality disorder

Biological understanding of a personality disorder is best achieved by examining the disorder's component dimensions, which for borderline personality disorder include impulsive aggression and affective instability. Current biological research into BPD aims to identify the neurotransmitters and brain regions implicated in each of these key domains. Because of advancing technologies and analytic strategies, structural and functional neuroimaging are at the forefront of such efforts. Structural neuroimaging, primarily in the form of magnetic resonance imaging (MRI) scans, gives information about the anatomy of the brain, while functional neuroimaging, primarily functional MRI (fMRI) and positron emission tomography (PET) scans, gives information about brain activity and neurotransmitter systems at the molecular level. BPD neuroimaging studies to date have implied the involvement of several neurotransmitter systems, principally serotonin, along with dysfunction of select brain regions, including the prefrontal cortex and amygdala, suggesting a "dual-brain pathology": "hyperarousal-dyscontrol syndrome." However, the exact mechanisms of all these putative etiologies remain unknown.