By Anne Harding

NEW YORK (Reuters Health) - Overweight and obese women are more likely to have antisocial personality disorder, paranoid personality disorder and extreme social phobia than their leaner peers, new research published in Psychosomatic Medicine shows.

On the other hand, for men, extra pounds seem to actually reduce their risk for paranoid personality disorder.

Dr. Jitender Sareen of the University of Manitoba in Winnipeg and his colleagues suggest in their report that antisocial and paranoid disorders could conceivably cause overweight and obesity in women, or vice versa -- or both.

People who are overweight or obese are known to be at higher risk of so-called Axis I psychiatric disorders, which include major depression, anxiety disorders, and substance abuse, Sareen told Reuters Health. However, the association between body weight and personality disorders (classified as Axis II disorders) is not as clear.

People are believed to develop personality disorders relatively early in life, before age 18. These disorders are considered to be fairly resistant to treatment, although evidence is mounting that certain types of personality disorder can indeed get better with the right kind of therapy.

Sareen and his colleagues looked at data from a 2001-2002 national survey on 43,093 US residents 18 and older. Study participants had been assessed for all seven different types of personality disorder.

Once the researchers accounted for Axis I disorders, socioeconomic and demographic characteristics, health problems, and other relevant factors, they found that the overweight and obese women were at greater risk of antisocial, paranoid, and avoidant personality disorder.

People with avoidant personality disorder are extremely shy and fearful of rejection, and avoid social interaction. Antisocial personality disorder, on the other hand, is characterized by disregard for the rights of other people.

The Canadian team also found that schizoid personality disorder, a relatively rare condition in which a person is not interested in social relationships and prefers to live a solitary, secretive life, was more common among underweight women. Overweight men were less likely to have paranoid personality disorder.

Women with avoidant or paranoid personalities may lead more sedentary lifestyles, making them more likely to gain weight, while the stigmatization overweight women may experience could itself lead to personality problems, the researchers say.

It's also possible that a shared underlying biological problem, such as abnormalities in the "reward hormone" dopamine, could contribute to personality disorder risk and the likelihood of being overweight.

"Lots of people get psychotherapy for Axis II disorders and over time they do change," Sareen noted, even though the benefits of psychodynamic therapy for these individuals has been "controversial." In the future, he added, it will be important to investigate whether treating such disorders may make it easier for people to maintain a healthy weight.

SOURCE: Psychosomatic Medicine, November/December 2008.

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