To our knowledge, no previous studies of personality disorders (PDs) in a large representative sample of the common population have been conducted.
A representative sample of 2053 individuals between the ages of 18 and 65 years in Oslo, the capital of Norway, was studied from 1994 to 1997. Information about PDs was obtained by means of the Structured Interview for DSM-III-R Personality Disorders, in conjunction with an interview recording demographic data. The subjects were interviewed primarily at home, but in some instances, also at the clinic.
The prevalence of PDs was 13.4% (SE, 0.7). The prevalence rates (SEs) for specific PDs, irrespective of whether a person had 1 or more PD, were: paranoid, 2.4% (0.3); schizoid, 1.7% (1.6); schizotypal, 0.6% (0.2); antisocial, 0.7% (0.2); sadistic, 0.2% (0.1); borderline, 0.7% (0.2); histrionic, 2.0% (0.3); narcissistic, 0.8; (0.2); avoidant, 5.0% (0.5); dependent, 1.5% (0.3); obsessive-compulsive: 2.0% (0.3); passive-aggressive, 1.7% (0.3); self-defeating, 0.8%, (0.2). The prevalence of PDs was highest among subjects with only a high school education or less, and living without a partner in the center of the city.
Personality disorders were found to be prevalent, with avoidant, schizoid, and paranoid PDs more common, and borderline PD less common than what is usually reported. Personality disorders tend to be more frequent among single individuals from the lower socioeconomic classes in the center of the city. It is impossible to determine what is cause and what is consequence from a cross-sectional study.