Classifying personality disorder

The way in which personality disorder is classified is transitioning from a categorical system to a system that describes personality disorder on a spectrum of severity.

The categorical classification distinguishes different types of personality disorders according to the dominant features that are characteristic of the person’s personality (eg paranoid, schizoid, schizotypal, antisocial, borderline, histrionic, narcissistic, avoidant, dependent, obsessive compulsive). However, this approach is problematic because the categories are overlapping, lack validity, and no clear threshold exists between types and degrees of personality disorders.

In contemporary practice, personality disorder is classified according to its severity, which may be accompanied by a specifier that describes the prominent personality traits or patterns characteristic of the person. This approach is reflected in both the International Classification of Diseases (ICD-11) and the Diagnostic and Statistical Manual of Mental Disorders (DSM-5).

The severity (mild, moderate or severe) is related to the breadth of maladaptive behaviour and the degree to which it impairs the person’s life, such as:

• the number of areas of personality functioning affected (eg personal, familial, social, educational, occupational)
• the number of interpersonal relationships affected
• the person’s ability to perform expected social and occupational roles
• the likelihood of inflicting harm to themselves or others
• the level of impairment or distress experienced in areas of functioning.

For example:

• a person with mild personality disorder would experience disturbances in some areas of personality functioning (eg ability to control impulses and change behaviour) and may have problems maintaining some relationships but would not usually self-harm or inflict harm on others
• a person with moderate personality disorder would experience disturbances in multiple areas of personality functioning but some areas are relatively less affected; they have problems in most interpersonal relationships and may self-harm or inflict harm to others
• a person with severe personality disorder has severely impaired functioning, such that they may only be able to participate in a few activities and all interpersonal relationships are affected; they often self-harm or inflict harm on others.

The prominent personality traits that may be specified with the severity classification include:

• negative affectivity—tendency to experience a broad range of negative emotions (eg sadness, anxiety), emotional lability, poor emotion regulation, negativistic attitudes, low self-esteem, low self-confidence and mistrust
• detachment—tendency to maintain emotional and interpersonal distance
• dissociality—a lack of empathy and disregard for the rights and feelings of others
• disinhibition—tendency to act rashly, usually due to an internal or external stimulus, without consideration of consequences
• anankastia—a narrow focus on a rigid standard of perfection, perceptions of right and wrong, and on controlling behaviours (both self and others) and situations to conform to these standards.

Multiple personality traits can be used in an individual, and it is usually necessary to do so for people with more severe personality disorder.

In addition to determining the severity and prominent personality traits, assess whether a borderline pattern may be specified. A borderline pattern is specified if the person has a pervasive pattern of instability of interpersonal relationships, self-image and affects, and marked impulsivity; this is considered the most severe specifier and is synonymous with borderline personality disorder in the categorical classification system.