Overview of Personality Disorders

Personality disorder
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According to a study published in the Journal of Clinical Psychiatry, an estimated 30.8 million American adults experience symptoms of at least one personality disorder. Just what are personality disorders, anyway? A personality disorder is a chronic and pervasive mental disorder that affects thoughts, behaviors and interpersonal functioning. The DSM-IV currently lists 10 different personality disorders, including borderline, antisocial and avoidant personality disorder.

You can learn more about the causes, diagnosis and treatments in this overview of personality disorders.

What are Personality Disorders?

According to the Diagnostic and Statistical Manual-IV, a personality disorder is an "enduring pattern of inner experience and behavior that deviates markedly from the expectation of the individual's culture, is pervasive and inflexible, has an onset in adolescence or early adulthood, is stable over time, and leads to distress or impairment."

Because these disorders are chronic and pervasive, they can lead to serious impairments in daily life and functioning.

What Causes Personality Disorders?

The causes of personality disorders are the subject of considerable debate and controversy. Some experts believe that personality disorders are caused by early experiences that prevented the development of normal thought and behavior patterns. Other researchers believe that biological or genetic influences are the root cause of personality disorders.

While a definitive cause has not been established, it is likely that a combination of genetic predisposition and environmental variables contribute to the development of personality disorders.

How are Personality Disorders Diagnosed?

In order to be diagnosed with a personality disorder, an individual must exhibit symptoms that meet the diagnostic criteria established in the DSM-IV.

  • These patterns of behavior must be chronic and pervasive, affecting many different aspects of the individual’s life, including social functioning, work, school and close relationships.
  • The individual must exhibit symptoms that affect two or more of the following areas: thoughts, emotions, interpersonal functioning and impulse control.
  • The pattern of behaviors must be stable across time and have an onset that can be traced back to adolescence or early adulthood.
  • These behaviors cannot be explained by any other mental disorders, substance abuse or medical conditions.

What are the Different Types of Personality Disorders?

Personality disorders are described on Axis II of the Diagnostic and Statistical Manual. The DSM-IV lists a total of ten different personality disorders. These disorders are classified into three separate clusters.

Cluster A - Odd or Eccentric Disorders

Cluster B - Dramatic, Emotional, or Erratic Disorders

Cluster C – Anxious or Fearful Disorders

Differential Diagnosis

Before a clinician can diagnose a personality disorder, they must rule out other disorders or medical conditions that may be causing the symptoms. The symptoms that characterize personality disorders are often similar to those of other disorders and illnesses. Personality disorders also commonly co-occur with other illnesses.

The following are potential differentials that must be ruled out before diagnosing an individual with a personality disorder:

  • Social Phobia
  • Post Traumatic Stress Disorder
  • Schizophrenia


American Psychiatric Association. (2000) Diagnostic and Statistical Manual of Mental Disorders (DSM-IV-TR). 4th ed. Washington, DC: Author.

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