Gordon Allport published theories of personality traits from the 1920s—and Henry Murray advanced a theory called personology, which influenced a later key advocate of personality disorders, Theodore Millon. Tests were developing or being applied for personality evaluation, including projective tests such as the Rorschach test, as well as questionnaires such as the Minnesota Multiphasic Personality Inventory. Around mid-century, Hans Eysenck was analysing traits and personality types, and psychiatrist Kurt Schneider was popularising a clinical use in place of the previously more usual terms character, temperament or constitution. American psychiatrists officially recognized concepts of enduring personality disturbances in the first Diagnostic and Statistical Manual of Mental Disorders in the 1950s, which relied heavily on psychoanalytic concepts. Somewhat more neutral language was employed in the DSM-II in 1968, though the terms and descriptions had only a slight resemblance to current definitions. The DSM-III published in 1980 made some major changes, notably putting all personality disorders onto a second separate axis along with "mental retardation", intended to signify more enduring patterns, distinct from what were considered axis one mental disorders. Inadequate and asthenic personality disorder categories were deleted, and others were expanded into more types, or changed from being personality disorders to regular disorders. Sociopathic personality disorder, which had been the term for psychopathy, was renamed Antisocial Personality Disorder. Most categories were given more specific operationalized definitions, with standard criteria psychiatrists could agree on to conduct research and diagnose patients. In the DSM-III revision, self-defeating personality disorder and sadistic personality disorder were included as provisional diagnoses requiring further study.
The pattern is stable and of long duration, and its onset can be traced back at least to adolescence or early adulthood. The enduring pattern is not better explained as a manifestation or consequence of another mental disorder. The enduring pattern is not attributable to the physiological effects of a substance (e.g., a drug of abuse, a medication) or another medical condition (e.g., head trauma). ICD-11
The ICD-11 personality disorder section differs substantially compared to the previous edition ICD-10. All distinct PDs have been merged into one: Personality disorder (6D10), which can be coded as Mild (6D10.0), Moderate (6D10.1), Severe (6D10.2), or severity unspecified (6D10.Z). There is also an additional category called Personality difficulty (QE50.7), which can be used to describe personality traits that are problematic, but do not meet the diagnostic criteria for a PD. A personality disorder or difficulty can be specified by one or more Prominent personality traits or patterns (6D11). The ICD-11 uses five trait domains: (1) Negative affectivity (6D11.0); (2) Detachment (6D11.1), (3) Dissociality (6D11.2), (4) Disinhibition (6D11.3), and (5) Anankastia (6D11.4). Listed directly underneath is Borderline pattern (6D11.5), a category similar to Borderline personality disorder. This is not a trait in itself, but a combination of the five traits in certain severity.