Borderline personality disorder (BPD), also known as emotionally unstable personality disorder, is a long-term pattern of abnormal behavior characterized by unstable relationships with other people, unstable sense of self, and unstable emotions.[3][4]There is often an extreme fear of abandonment, a feeling of emptiness, and self-harm. Symptoms may be brought on by seemingly normal events.[3] The behavior typically begins by early adulthood, and occurs across a variety of situations.[4] Substance abuse, depression, and eating disorders are commonly associated with BPD.[3] About 10% of those with BPD die by suicide.[3][4]

BPD’s causes are unclear, but seem to involve genetic, brain, environment, and social factors. It occurs about five times more often in a person who has an affected close relative.[3] Adverse life events also appear to play a role. The underlying mechanism appears to involve the frontolimbic network of neurons.[5] BPD is recognized by the Diagnostic and Statistical Manual of Mental Disorders (DSM) as personality disorder along with nine other such disorders.[4] Diagnosis is based on the symptoms while a medical exam may be done to rule out other problems.[3] The condition must be differentiated from an identity problem or substance use disorders, among other possibilities.[4]

Borderline personality disorder is typically treated with therapy, such as cognitive behavioral therapy (CBT). Another type, dialectical behavior therapy (DBT) has been found to reduce the risk of suicide. Therapy may occur one-on-one, or in a group. While medications do not cure BPD, they may be used to help with the associated symptoms. Some people require care in hospital.[3]

About 1.6% of people have BPD in a given year.[3] Females are diagnosed about three times as often as males. It appears to become less common among older people. Up to half of people improve over a ten-year period. People affected typically use a high amount of healthcare resources.[4] There is an ongoing debate about the naming of the disorder, especially the suitability of the word “borderline”.[3]