Personality disorders are regarded as being among the more important categories within the DSM-IV diagnostic nomenclature, because they have the unique distinction of being placed on a separate diagnostic axis. However, empirical data have pointed out a number of disadvantages and concerns with the categorical system: excessive co-occurrence, inadequate coverage, heterogeneity within diagnoses, arbitrary and unstable diagnostic boundaries and inadequate scientific basis.

Alternative dimensional approaches have been considered. There is a surprising consistency over the number and descriptions of the main factors or dimensions both in normal population and among psychiatric patients, at least the following four: an externalizing factor aggression (antagonism), an internalizing anxious-emotional unstable second factor, an inhibited and constraint third factor and fourth factor of compulsivity and perfectionism. Beside this, severity of functional deficits, a number of trait domains and disturbances of self and identity are considered to be included as additional descriptors of personality pathology. It is proposed that only 5 or 6 of the current categories with highest clinical validity will be kept in the system. The aim is to maximize clinical utility, but the current suggestions seem to be too complex for the average clinician to follow.