What is borderline personality disorder?

Borderline personality disorder is a serious mental illness marked by unstable moods, behavior, and relationships. In 1980, the Diagnostic and Statistical Manual for Mental Disorders, Third Edition (DSM-III) listed borderline personality disorder as a diagnosable illness for the first time. Most psychiatrists and other mental health professionals use the DSM to diagnose mental illnesses.

Because some people with severe borderline personality disorder have brief psychotic episodes, experts originally thought of this illness as atypical, or borderline, versions of other mental disorders.¹ While mental health experts now generally agree that the name "borderline personality disorder" is misleading, a more accurate term does not exist yet.

Most people who have borderline personality disorder suffer from:

• Problems with regulating emotions and thoughts
• Impulsive and reckless behavior
• Unstable relationships with other people.

People with this disorder also have high rates of co-occurring disorders, such as depression, anxiety disorders, substance abuse, and eating disorders, along with self-harm, suicidal behaviors, and completed suicides.

According to data from a subsample of participants in a national survey on mental disorders, about 1.6 percent of adults in the United States have borderline personality disorder in a given year.²

Borderline personality disorder is often viewed as difficult to treat. However, recent research shows that borderline personality disorder can be treated effectively, and that many people with this illness improve over time.^1,3,4

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