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What is borderline personality disorder?

Borderline Personality Disorder

Borderline personality disorder (BPD) is a serious mental illness marked by unstable moods, behavior and relationships. Because some people with severe BPD have brief psychotic episodes, experts originally thought of this illness as atypical, or borderline, versions of other mental disorders.


Scientists generally agree that genetic and environmental factors are likely to be involved, however, studies suggest that the illness is strongly inherited. Social and cultural factors may increase the risk for BPD. For example, being part of a community or culture in which unstable family relationships are common may increase a person's risk for the disorder.


Signs and Symptoms:

  • Extreme reactions - including panic, depression, rage, or frantic actions - to abandonment, whether real or perceived
  • A pattern of intense and stormy relationships with family, friends, and loved ones, often veering from extreme closeness and love (idealization) to extreme dislike or anger (devaluation)
  • Distorted and unstable self-image or sense of self, which can result in sudden changes in feelings, opinions, values, or plans and goals for the future (such as school or career choices)
  • Impulsive and often dangerous behaviors, such as spending sprees, unsafe sex, substance abuse, reckless driving, and binge eating
  • Recurring suicidal behaviors or threats for self-harming behavior such as cutting
  • Intense and highly changeable moods, with each episode lasting from a few hours to a few days
  • Chronic feelings of emptiness and/or boredom
  • Inappropriate, intense anger or problems controlling anger
  • Having stress-related paranoid thoughts or severe dissociative symptoms, such as feeling cut off from oneself, observing oneself from outside the body, or losing touch with reality


Borderline personality disorder is often under-diagnosed or misdiagnosed.


A mental health professional experienced in diagnosing and treating mental disorder - such as a psychologist - can detect BPD based on a thorough interview and a discussion about symptoms. A careful and thorough medical exam can help rule out other possible causes of symptoms.


The mental health professional may ask about symptoms and personal and family medical histories, including any history or mental illnesses. This information can help the mental health professional decide on what the best treatment will be.