Personality disorders

Personality disorders form a class of mental disorders that are characterized by long-lasting rigid patterns of thought and behaviour. Because of the inflexibility and pervasiveness of these patterns, they can cause serious problems and impairment of functioning for the persons who are afflicted with these disorders.

Personality disorders are seen by the American Psychiatric Association as an enduring pattern of inner experience and behaviour that deviates markedly from the expectations of the culture of the individual who exhibits it. These patterns are inflexible and pervasive across many situations. The onset of the pattern can be traced back at least to the beginning of adulthood. To be diagnosed as a personality disorder, a behavioural pattern must cause significant distress or impairment in personal, social, and/or occupational situations.

DSM criteria
Personality disorders are represented on Axis II of the diagnostic manual of the American Psychiatric Association, the Diagnostic and Statistical Manual of Mental Disorders (DSM, or DSM-IV as it is currently in its fourth edition) (see also: DSM cautionary statement).

General diagnostic criteria for a personality disorder
To make a diagnosis of a personality disorder, these criteria must be satisfied in addition to the specific criteria listed under the individually named personality disorders.

A. An enduring pattern of inner experience and behaviour that deviates markedly from the expectations of the individual's culture. This pattern is manifested in two (or more) of the following areas:
 * cognition (perception and interpretation of self, others and events)
 * affectivity (the range, intensity, lability, and appropriateness of emotional response)
 * interpersonal functioning
 * impulse control

B. The enduring pattern is inflexible and pervasive across a broad range of personal and social situations.

C. The enduring pattern leads to clinically significant distress or impairment in social, occupational, or other important areas of functioning.

D. The pattern is stable and of long duration and its onset can be traced back at least to adolescence or early adulthood.

E. The enduring pattern is not better accounted for as a manifestation or consequence of another mental disorder.

F. The enduring pattern is not due to the direct physiological effects of a substance or a general medical condition such as head injury.

Persons under 18 years old who fit the criteria of a personality disorder are usually not diagnosed with such a disorder, although they may be diagnosed with a related disorder. Antisocial personality disorder cannot be diagnosed at all in persons under 18.

List of personality disorders defined in the DSM
The DSM-IV lists ten personality disorders, which are grouped into three clusters:

Cluster A (odd or eccentric disorders)
 * Paranoid personality disorder
 * Schizoid personality disorder
 * Schizotypal personality disorder

Cluster B (dramatic, emotional, or erratic disorders)
 * Antisocial personality disorder
 * Borderline personality disorder
 * Histrionic personality disorder
 * Narcissistic personality disorder

Cluster C (anxious or fearful disorders)
 * Avoidant personality disorder
 * Dependent personality disorder
 * Obsessive-compulsive personality disorder (not the same as Obsessive-compulsive disorder)

The DSM-IV also contains a category for behavioural patterns that do not match these ten disorders, but nevertheless have the characteristics of a personality disorder; this category is labeled Personality Disorder NOS (Not Otherwise Specified). The previous version of the DSM also contained the Passive-Aggressive Personality Disorder and the Self-Defeating Personality Disorder. Passive-Aggressive Personality Disorder is a pattern of negative attitudes and passive resistance in interpersonal situations. Self-defeating personality disorder is characterised by behaviour that consequently undermines the person's pleasure and goals. These categories were removed in the current version of the DSM, because it is questionable whether these are separate disorders.

Current thinking and criticism
The DSM attempts to represent a consensus view of the members of the American Psychiatric Association. However, more so than in other parts of the DSM, the classification of Axis II personality disorders&mdash;deeply ingrained, maladaptive, lifelong behaviour patterns&mdash;has come under sustained and serious criticism from its inception in 1952. The DSM adopts a categorical approach, assuming that personality disorders are "qualitatively distinct clinical syndromes" (p. 689). This is doubted by many. The polythetic form of the DSM's Diagnostic Criteria&mdash;only a subset of the criteria is adequate grounds for a diagnosis&mdash;generates diagnostic heterogeneity. In other words, people diagnosed with the same personality disorder may share only one criterion or none. Some people think that this is unacceptable.

The DSM has arbitrarily separated off Axes I and II so that it:
 * "... ensures that consideration will be given to the possible presence of Personality Disorders and Mental Retardation that might otherwise be overlooked when attention is directed to the usually more florid Axis I disorders. The coding of Personality Disorders on Axis II should not be taken to imply that their pathogenesis or range of appropriate treatment is fundamentally different from that of the disorders coded on Axis I."

However, the DSM does not contain an explanation of the relationship between Axis II (personality) and Axis I (non-personality) disorders, or the way in which chronic childhood and developmental problems interact with personality disorders. Some people think that the differential diagnoses are vague and the personality disorders are insufficiently demarcated. This overlap is addressed in the DSM by grouping the personality disorders into three clusters, which contain similar disorders. The result of the overlap is excessive comorbidity: people often receive multiple Axis II diagnoses. This casts doubt on the assumption that the diagnostic categories correspond to independent disorders. The necessity of the "not otherwise specified" basket category can also be seen as an indication of poor construct validity; the current diagnostic categories are apparently insufficient to categorize all people with personality disorders.

The distinction made between "normal" and "disordered" personalities is also rejected by some. The "diagnostic thresholds" between normal and abnormal are either absent or weakly supported. The judgment whether a behavioural pattern is normal or disordered is also highly subjective. The DSM contains little discussion of what distinguishes personality styles (personality), from personality disorders and much is left to clinical judgment.

Cultural bias is evident in certain disorders such as Schizoid personality disorder, Antisocial personality disorder, and Schizotypal personality disorder. Also, diagnosis of some disorders may be vulnerable to bias because of gender role expectations. 1

The emergence of dimensional alternatives to the categorical approach is acknowledged in the DSM-IV-TR itself:
 * "An alternative to the categorical approach is the dimensional perspective that Personality Disorders represent maladaptive variants of personality traits that merge imperceptibly into normality and into one another" (p.689)

Despite considering all of the above, the DSM continues for the present to prefer the use of a categorical approach over a dimensional approach which is seen as, "less useful than categorical systems in clinical practice and in stimulating research."

The following issues, long neglected in the DSM, are likely to be addressed in future editions as well as in current research:
 * Development of disorders over time
 * Genetic and biological underpinnings of personality disorders
 * Development of personality psychopathology during childhood and its emergence in adolescence
 * Interactions between physical health and disease and personality disorders
 * Effectiveness of various treatments (talk therapies as well as psychopharmacology)

Footnote
[1] See also the note about this subject in the DSM cautionary statement