What causes personality disorders?

Research suggests that genetics, abuse and other factors contribute to the development of obsessive-compulsive, narcissistic or other personality disorders.

In the past, some believed that people with personality disorders were just lazy or even evil. But new research has begun to explore such potential causes as genetics, parenting and peer influences:

• Genetics. Researchers are beginning to identify some possible genetic factors behind personality disorders.

  • One team, for instance, has identified a malfunctioning gene that may be a factor in obsessive-compulsive disorder.

  • Other researchers are exploring genetic links to aggression, anxiety and fear — traits that can play a role in personality disorders.

• Childhood trauma. Findings from one of the largest studies of personality disorders, the Collaborative Longitudinal Personality Disorders Study, offer clues about the role of childhood experiences.

  • One study found a link between the number and type of childhood traumas and the development of personality disorders. People with borderline personality disorder, for example, had especially high rates of childhood sexual trauma.  

• Verbal abuse. Even verbal abuse can have an impact. In a study of 793 mothers and children, researchers asked mothers if they had screamed at their children, told them they didn’t love them or threatened to send them away. Children who had experienced such verbal abuse were three times as likely as other children to have borderline, narcissistic, obsessive-compulsive or paranoid personality disorders in adulthood.

• High reactivity. Sensitivity to light, noise, texture and other stimuli may also play a role.

  • Overly sensitive children, who have what researchers call “high reactivity,” are more likely to develop shy, timid or anxious personalities.

  • However, high reactivity’s role is still far from clear-cut. Twenty percent of infants are highly reactive, but less than 10 percent go on to develop social phobias.

• Peers. Certain factors can help prevent children from developing personality disorders.

  • Even a single strong relationship with a relative, teacher or friend can offset negative influences, say psychologists.

 Adapted from “Where personality goes awry” APA Monitor on Psychology^®