Personality Disorders Community

What Causes Someone to Develop a Personality Disorder

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Detailed information on the causes of personality disorders, how personality disorders develop and why.

Personality disorders are thought to result from a bad interface, so to speak, between a child's temperament and character on one hand and his or her family environment on the other. Temperament can be defined as a person's innate or biologically shaped basic disposition. Human infants vary in their sensitivity to light or noise, their level of physical activity, their adaptability to schedules, and similar traits. Even such traits as shyness or novelty-seeking may be at least in part determined by the biology of the brain and the genes one inherits.

Character is defined as the set of attitudes and behavior patterns that the individual acquires or learns over time. It includes such personal qualities as work and study habits, moral convictions, neatness or cleanliness, and consideration of others. Since children must learn to adapt to their specific families, they may develop personality disorders in the course of struggling to survive psychologically in disturbed or stressful families. For example, nervous or high-strung parents might be unhappy with a baby who is very active and try to restrain him or her at every opportunity. The child might then develop an avoidant personality disorder as the outcome of coping with constant frustration and parental disapproval. As another example, child abuse is believed to play a role in shaping borderline personality disorder. One reason that some therapists use the term developmental damage instead of personality disorder is that it takes the presumed source of the person's problems into account.


Some patients with personality disorders come from families that appear to be stable and healthy. It has been suggested that these patients are biologically hypersensitive to normal family stress levels. Levels of the brain chemical (neurotransmitter) dopamine may influence a person's level of novelty-seeking, and serotonin levels may influence aggression.

Other factors that have been cited as affecting children's personality development are the mass media and social or group hysteria, particularly after the events of September 11, 2001. Cases of so-called mass sociogenic illness have been identified, in which a group of children began to vomit or have other physical symptoms brought on in response to an imaginary threat. In two such cases, the children were reacting to the suggestion that toxic fumes were spreading through their school. Some authors believe that overly frequent or age-inappropriate discussions of terrorist attacks or bioterrorism may make children more susceptible to sociogenic illness as well as other distortions of personality.

Personality Disorder Behaviors


Detailed information on the causes of personality disorders, how personality disorders develop and why.To meet the diagnosis of personality disorder, which is sometimes called character disorder, the patient's problematic behaviors must appear in two or more of the following areas:

  • perception and interpretation of the self and other people
  • intensity and duration of feelings and their appropriateness to situations
  • relationships with others
  • ability to control impulses

Personality disorders have their onset in late adolescence or early adulthood. Doctors rarely give a diagnosis of personality disorder to children on the grounds that children's personalities are still in the process of formation and may change considerably by the time they are in their late teens. In retrospect, however, many individuals with personality disorders could be judged to have shown evidence of the problems in childhood.

It is difficult to give close estimates of the percentage of the population that has personality disorders. Patients with certain personality disorders, including antisocial and borderline disorders, are more likely to get into trouble with the law or otherwise attract attention than are patients whose disorders chiefly affect their capacity for intimacy. On the other hand, some patients, such as those with narcissistic or obsessive-compulsive personality disorders, may be outwardly successful because their symptoms are useful within their particular occupations. It has, however, been estimated that about 15% of the general population of the United States has a personality disorder, with higher rates in poor or troubled neighborhoods. The rate of personality disorders among patients in psychiatric treatment is between 30% and 50%. It is possible for patients to have a so-called dual diagnosis; for example, they may have more than one personality disorder, or a personality disorder together with a substance-abuse problem.

By contrast, DSM-IV classifies personality disorders into three clusters based on symptom similarities:

Cluster A (paranoid, schizoid, schizotypal): Patients appear odd or eccentric to others.
Cluster B (antisocial, borderline, histrionic, narcissistic): Patients appear overly emotional, unstable, or self-dramatizing to others.
Cluster C (avoidant, dependent, obsessive-compulsive): Patients appear tense and anxiety-ridden to others.

The DSM-IV clustering system does not mean that all patients can be fitted neatly into one of the three clusters. It is possible for patients to have symptoms of more than one personality disorder or to have symptoms from different clusters.

next: Diagnosis of Personality Disorders