Personality describes the innate and enduring characteristics of an individual which shape their attitudes, thoughts, and behaviours in response to situations. We all recognize, amongst people we know well, some who manifest certain characteristics more than others: shyness, confidence, anger, generosity, tendency to display emotions, sensitivity, and being pernickety to name but a few. When these enduring characteristics of an individual are such as to cause distress or difficulties for themselves or in their relationships with others then they can be said to be suffering from personality disorder (PD). PD is separate from mental illness, although the two interact.

Definition

The following definition is based on ICD-10 and DSM-IV (both are very similar). PDs are enduring (starting in childhood or adolescence and continuing into adulthood), persistent, and pervasive disorders of inner experience and behaviour that cause distress or significant impairment in social functioning. PD manifests as problems in cognition (ways of perceiving and thinking about self and others), affect (range, intensity, and appropriateness of emotional response), and behaviour (interpersonal functioning, occupational and social functioning, and impulse control). To diagnose PD, the manifest abnormalities should not be due to other conditions (such as psychosis, affective disorder, substance misuse, or organic disorder) and should be out of keeping with social and cultural norms.

The development of clinical concepts of conditions which would today be recognized as PD started in the early nineteenth century, at a time when the main two groups of mental conditions acknowledged by psychiatrists were insanity and idiocy. It became clear that there were individuals who were neither insane (i.e. suffering from delusions or hallucinations) nor clearly idiots, imbeciles, or morons (to use the then contemporary terminology for learning disability), but who nevertheless had abnormalities in their behaviour.

The individual PD subtypes in use today derive from a number of different academic and theoretical backgrounds: antisocial (dissocial) PD from child psychiatric follow-up studies; borderline, histrionic, and narcissistic PDs from dynamic theory and psychotherapeutic practice; schizoid and anankastic PDs from European phenomenology; and avoidant PD from academic psychology. Notably absent from the list of academic sources is the psychological study of normal personality which has developed a trait model of normal personality along a varying number of axes (b p. 493).

Controversy

There is ongoing debate about the clinical usefulness, diagnosis, categorization and description of PD. A frequently repeated criticism of the present clinical concept has been the problem of tautology. That is, the same features displayed by a patient which suggest a diagnosis of PD are then ‘explained’ by the presence of that diagnosis. For example a patient may, among other features, display ‘an incapacity to experience guilt’ and ‘a low threshold for discharge of frustration, including violence’. This may lead to an ICD-10 diagnosis of dissocial PD. It is then illogical to use that same diagnosis to ‘explain’ a subsequent episode of violence without remorse in that individual.

Some psychiatrists believe that psychiatry has no role in the treatment of people with PDs. They argue that:

• Personality is by definition unchangeable.
• There is no evidence that psychiatry helps individuals with PD.
• These people are disruptive and impinge negatively on the treatment of other patients.
• These people are not ill and are responsible for their behaviour.
• Psychiatry is being asked to deal with something that is essentially a social problem.

On the other hand there are those who believe that people with PD clearly fall within the remit of psychiatry, arguing:

• People with PD suffer from symptoms related to their disorder.
• They have high rates of suicide, other forms of premature death, and of other mental illnesses.
• There are treatment approaches which are effective.
• Their opponents are rejecting patients because they dislike them.
• The problem is not that these people cannot be helped but that traditional psychiatric services do not provide the type of approach and services that are necessary.

‘Normal’ personality

Psychologists have sought to conceptualize and describe the variations in normal personality. There are two main approaches: nomothetic and ideographic.1 In general these approaches have developed separately from concepts of abnormal personality and PD.

Nomothetic approaches

Personality seen in terms of attributes shared by individuals. Two subdivisions: type (or categorical) approaches (discrete categories of personality); and trait (or dimensional) approaches (a limited number of qualities, or traits, account for personality variation). Type approaches dominate the description and classification of PD, but trait approaches are pre-eminent in modern personality psychology.

Type approaches These describe individual personality by similarity to a variable number of predefined archetypes. These may attempt to include all aspects of personality and behaviour—the ‘broad’ models—or they may describe one aspect of personality—the ‘narrow’ models. An example of the former is the humoral model of Hippocrates which described four fundamental personality types (choleric, sanguine, melancholic and phlegmatic); an example of the latter is the type A vs. type B model which describes groups of behaviours exhibited by people at higher and lower risk of cardiac disease.

Trait approaches These view a variable number of traits as continuous scales along which each person will have a particular position; the positions on all the traits represent a number of dimensions which describe personality. Examples include: Eysenck’s three-factor theory (neuroticism, extraversion, psychoticism); Costa and McCrae’s five-factor model (neu-roticism, extraversion, openness, agreeableness, conscientiousness); Cloninger’s seven-factor model (novelty-seeking, harm avoidance, reward dependence, persistence, self-directedness, cooperativeness, self-transcendence; originally only first 3 factors); Cattell’s sixteen-factor theory. A consensus has emerged from personality questionnaire research and from lexical approaches that there are five fundamental traits (the ‘big five’) similar to those of Costa and McCrae. The heritability of personality traits in twin and adoptive studies has been found to be moderately large (about 30%).

Ideographic approaches

Unlike nomothetic approaches, these emphasize individuality and seek to understand an individual’s personality by understanding that individual and their development rather than by reference to common factors. Examples are psychoanalytic, humanistic, and cognitive–behavioural approaches. The first two have little scientific validity and the last has compromised with trait theorists.

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Is personality stable?

Are there traits which are persistent and predict a person’s behaviour over time in a number of situations? Situationists have argued that the situation was a stronger determinant of behaviour than personality traits. However, more recent research has demonstrated the long-term stability of a number of personality traits and, perhaps unsurprisingly, most now agree that both the situation and personality traits are important in determining behaviour.

Classification of personality disorder

It is largely accepted that normal personality is best described and classified in terms of dimensions or traits. Although this also applies to PD, our current psychiatric classifications are categorical. The various categories of PD described in ICD-10 and DSM-IV have a number of origins: psychodynamic theory, apparent similarities between certain PDs and certain mental illnesses, and descriptions of stereotypical personality types. The various categories used come together in a piecemeal and arbitrary fashion and do not represent any systematic understanding or study of PD. The categorical classification of PD is psychiatric classification at its worst.

There are a number of important points to bear in mind when using standard categorical approaches in the diagnosis of PDs:

• Due to their heterogeneous origins, there is overlap between the criteria for some categories.
• It is more common for individuals to meet the criteria for more than one category of PD than to meet only the criteria for a single category.
• When making a diagnosis one should use all the categories for which a person meets the criteria.
• If a person meets criteria for more than one category, then they do not suffer from more than one actual disorder. A person has a personality and this may or may not be disordered. If it is disordered it may have various features which are rarely described adequately by a particular category.
• Clinically it is more important to understand and describe the specific features of a person’s personality than it is to assign them to a particular category.