Borderline personality disorder (BPD) is a serious mental health condition that causes patients to have unstable personal relationships, intense anger, emotional emptiness and fears of abandonment. About 2 percent of the general population has BPD, according to the American Psychiatric Association (APA). However, this is based on limited information.

Borderline personality gets its name from an earlier belief that the disorder shared characteristics of psychotic and neurotic (disturbed mental health) conditions. However, experts no longer view this definition as accurate. Instead, patients with BPD are said to have a problem regulating emotions, and are in a constant state of emotional turmoil. They may be calm and rational for long periods of time before experiencing sudden feelings of rage.

People with BPD sometimes view themselves as bad or unworthy, and tend to see themselves as misunderstood or mistreated. They may deny responsibility for their feelings and actions by using defense mechanisms such as “splitting.” During splitting patients elevate some people in their lives to a high status while totally devaluing others.  Patients may also use a defense mechanism called “projective identification,” in which they deny their own feelings and instead attribute them to someone else.

BPD affects people of all ages, but most often is diagnosed in adolescents and young adults. Women are far more likely to be diagnosed with BPD than men, and account for 75 percent of all cases, according to the APA.

People with BPD often show a lifelong tendency toward impulsiveness, strong emotions and intense relationships. In many cases, BPD that develops during young adulthood gradually diminishes as patients grow older. Greater stability frequently begins to appear in a patient’s 30s or 40s, particularly in those who seek treatment.

Many other mental health disorders are associated with BPD, particularly mood disorders (e.g., major depression, bipolar disorder). Other mental illnesses associated with BPD include:

• Anxiety disorders (e.g., post-traumatic stress disorder)
  
  
• Substance abuse
  
  
• Other personality disorders
  
  
• Attention deficit hyperactivity disorder(ADHD)