Personality disorder (pds): a heterogeneous group of disorders that are coded on axis ii of the dsm. They are regarded as long-standing, pervasive and inflexible patterns of behaviour and inner experience that deviate from the expectation of a person"s culture and that impair social and occupational functioning (some but not all cause emotional distress) An actual personality disorder is defined by extremes of several traits and by the inflexible way these traits are expressed. They are often rigid in their behaviour and cannot change it in response to changes in the situation they experience. Individuals would not be diagnosed as having personality disorders unless the patterns of behaviour were long-standing, pervasive and dysfunctional. The reliability of personality disorder diagnoses have improved because of 2 developments. The development of structured interviews specially designed for assessing personality disorders. Test-rests reliability is also an important factor for evaluation. Anti-social personality disorder has a high test-retest reliability, indicating that it is a stable diagnosis.