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 University Medical College and tested at Cornell University 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, Ph.D., a psychopathologist at Cornell in Ithaca.

In tests, no cases of definite personality pathology were missed by this two-stage procedure, and the researchers believe that it may help reduce the number of professional interviews required for diagnosis by about one-half 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 and an associate professor of psychology in psychiatry at the Cornell University Medical College in New York City.

"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."

Personality disorders are enduring and impairing behaviors that generally fall into one of three groups: odd/eccentric, emotional/erratic/dramatic or anxious/fearful behaviors. Common disorders include conditions such as the "borderline," "schizotypal" and "antisocial" personality disorders.

Lenzenweger's collaborators included Armand W. Loranger, Ph.D., the developer of the screening test and a professor at Cornell University Medical College; Lauren Korfine, A.M., of Harvard University; and Cynthia Neff, Ph.D., of the University of Illinois at Urbana-Champaign. Their study is published in the April issue of Archives of General Psychiatry (Vol. 54, pp 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 subsamples 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 were 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."

Previously, researchers have generated "best-guess" estimates of the prevalence of personality disorders in the population, and these "guesses" have ranged between 5 and 15 percent of the general population. 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.

This screening and diagnostic procedure was part of the initial phase of the Longitudinal Study of Personality Disorders (LSPD), which Lenzenweger is conducting. The LSPD is a large-scale longitudinal study of normal personality, temperament, personality disorders and psychopathology now under way at Cornell. Lenzenweger teaches abnormal psychology and advanced experimental psychopathology at Cornell.

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