The American Psychiatric Association defines personality disorders as "an enduring pattern of the inner experience and behavior that deviates markedly from the expectations of the culture of the individual who exhibits it."
A diagnosis of a Personality Disorder means that there is an ongoing, rigid pattern of behavior that results in serious problems and impairment in a person's functioning. These patterns of behavior cannot be attributed to any other mental or physical disorder.
- Symptoms must be longstanding (over a year)
- The symptoms must be intense. The feelings are experienced with a much greater intensity than is "reasonable."
- The symptoms are experienced throughout most relationships (pervasive). If symptoms are only evident with certain people, the clinical definition for a personality disorder is not met.
Finally, personality disorders are developed as a personality is developed. As a result, personality disorders develop by early adulthood, even if not diagnosed until later.