Borderline personality disorder (BPD) is a serious and complex mental illness that affects 2 – 3% of the population. Once thought to be on the “border” of schizophrenia, BPD is now believed to be more closely related to mood disorders such as depression, or possibly to impulse control disorders like Attention-Deficit/Hyperactivity Disorder. People with BPD have difficulty regulating their emotions and controlling their impulses.