Although personality disorders can cause long-term suffering and disability, they are difficult to detect. As a result, many people go untreated.

A new screening procedure, developed at Cornell Medical College in New York City and tested at Cornell in Ithaca, coupled with a follow-up interview, reliably identified persons with personality pathology with a self-administered true-false questionnaire. In the second stage, those identified with possible personality disorders are interviewed by a professional clinician to confirm or discount an actual personality diagnosis, reports Mark Lenzenweger, a Cornell psychopathologist.

In tests, no cases of definite personality pathology were missed by this two-stage procedure, and the researchers believe that it may help reduce by about one-half the number of professional interviews required for diagnosis in large-scale epidemiological studies.

Based on their second-stage study of 258 individuals, Lenzenweger and his colleagues estimated that 11 percent of their nonclinical population had a diagnosable personality disorder, a rate consistent with previous "best-guess" estimates.

"Whereas researchers have a good grasp of the epidemiology for most other major mental disorders, we still don't have good estimates for personality disorders because their diagnosis requires considerable -- and costly -- clinical sophistication," said Lenzenweger, associate professor of human development and director of the Laboratory of Experimental Psychopathology at Cornell in Ithaca and an associate professor of psychology in psychiatry at Cornell Medical College.

"This is the first time we have hard data on just how prevalent personality disorders are in a nonclinical population," added Lenzenweger, a clinical psychologist and psychopathology researcher. "By interviewing only screened positive cases with little or no loss in diagnostic accuracy, it appears we have a screening tool that could help us to conduct major epidemiological studies of personality disorders by screening large numbers of people relatively inexpensively and accurately."

Lenzenweger's collaborators included Armand W. Loranger, the developer of the screening test and a professor at Cornell Medical College; Lauren Korfine of Harvard University; and Cynthia Neff of the University of Illinois at Urbana-Champaign. Their study is published in the April issue of Archives of General Psychiatry (Vol. 54, pages 345-351).

To test the new screening instrument, the researchers used a two-stage approach in which they administered the instrument to 2,000 individuals and received 1,646 inventories. From these data, the researchers identified 43 percent with possible personality disorders and 57 percent with no personality disorders. The researchers then selected sub samples from each of these two groups for a total of 258 subjects who then were interviewed in-depth.

Of the 134 identified with possible personality disorders, 21 cases were confirmed. Of the 124 identified as showing no possible personality disorders from the initial screening, none was later diagnosed with a personality disorder.

"These are exactly the kind of findings one would want from a screening," Lenzenweger said. "There were no false negatives. In other words, no genuine cases were missed."

Personality disorders are inflexible and enduring maladaptive personality conditions that cause significant distress or impairment in social, occupational or other areas of functioning.

These behaviors or traits include paranoid, schizoid (excessively detached from others), borderline (impulsive behavior, self-mutilation and stormy relationships), narcissistic (grandiose thoughts or behaviors, need for admiration and lack of empathy), antisocial, histrionic (over-emotional and attention seeking), dependent, sadistic, passive/aggressive and obsessive-compulsive personality disorders, among others.

The research was supported, in part, with a grant from the National Institute of Mental Health.