Borderline personality disorder (BPD) is a mental illness marked by black-and-white thinking and an instability in mood, self-image, behavior, and interpersonal relationships. BPD is often comorbid with anxiety and mood disorders (including bipolar disorder). The disorder occurs in approximately 1% to 2% of the general population, and is more common in women than men, with a 3:1 ratio. BPD also includes difficulty in controlling anger, or anger over small things, chronic emptiness, fear of abandonment, self-harm, or suicidal behavior. The term "borderline" originated from the idea that one could be borderline between psychosis and neurosis, athough this idea has fallen out of favor. Numerous studies have shown there is a relation between BPD and childhood sexual abuse. Many with BPD report having been abused or neglected as a child. There may also be a genetic factor. One study of identical twins found that when one twin had BPD there would be a 35% chance that the other would have BPD.[1] In a study in 2003 patients with BPD showed much more activity in the left amygdala than in the right.
Borderline personalities are people who have been hurt so badly they are afraid and on maximum alert all the time. --Patrick Carnes The Betrayal Bond, page 8