What are the core characteristics of personality disorders?

Personality disorders are common, influence the interaction between healthcare professionals and patients, are a strong predictor of treatment outcome, are a cause of premature death and are a great cost to society. Therefore, personality disorders must be an important part of any psychiatric assessment. The formal classification began when Kurt Schneider described a group of 'psychopathic personalities' in 1923. The classification included an essential core of personality disorder: the inability to form and maintain relationships. The requirements for the diagnosis of personality disorder are as follows: a pervasive pattern of maladaptive traits and behaviors that begin in early adult life and lead to significant personal distress and/or social dysfunction, and disruption to others. However, the description of specific personality disorders has always had a subjective component.

Which diagnostic criteria are used?

Diagnosing personality disorders is difficult. The disorder must be lifelong or at least of many years' duration and it must influence interaction with others. Another difficulty is that patients often do not recognize that they, and not others, are defective in their relationships. The DSM-5 review of the DSM-IV included a hybrid model to classify personality disorder, in which the severity was determined by the assessment of impairments in personal functioning. They also reduced the categories of disorders from 10 to 6, and assessed five areas of pathological personality trait domains. This was a major change from the categorical DSM-IV. However, according to the APA, this model was not yet ready for general use, and is therefore placed in a separate section of the DSM-5: Emerging Measures and Models. The DSM-IV classification was therefore retained, in which 10 categories are subdivided into three clusters. Cluster A includes the paranoid, schizoid and schizotypal categories. Cluster B includes the antisocial, borderline, histrionic and narcissistic categories. Cluster C includes the avoidant, dependent, and obsessive-compulsive categories. The three clusters are often used because there is a lot of comorbidity between the individual categories, which makes classification difficult, and because it is easier for researchers to consider 3 clusters than 10 disorders. Widiger and Simonsen saw that four dimensions cover the range of personality disorder: emotional disregulation, extraversion, antagonism and constraint.

What is the prevalence of personality disorders?

Research in Western Europe and North America indicates a prevalence of personality disorders between 4 and 15%. Only one study has been conducted into international prevalence. This led to a 6.1% prevalence, with the lowest prevalences in Europe and the highest in North and South America. It is just as common among men and women, and just as common among ethnic minorities as majority populations. A quarter of primary health care patients have a personality disorder, and 50% of out-patient psychiatric patients. The highest prevalence is among people who have contact with the criminal justice system (75%). Because women seek help more often than men, they are overrepresented in clinical settings.

What are the implications of personality disorders?

People with personality disorder have higher morbidity and mortality than those without. The higher death rate can be party explained by an increase in suicide and homicide. However, difficulties in relationships can effect relationships with care professionals, leading to misunderstandings, miscommunication and poor quality of care. Lifestyle factors such as smoking, alcohol and substance abuse are also important.

How does assessment of personality disorders take place?

Personality disorders are rarely diagnosed in practice, and if they are, then the most assigned categories are borderline, antisocial personality disorder, or not otherwise specified. Few clinicians take the trouble to diagnose a personality disorder due to the complexity of the diagnostic system. However, there is also stereotyping, because people who show self-damaging behavior are almost automatically diagnosed with borderline and people who are aggressive and break the law are quickly diagnosed with antisocial personality disorder. One of the major difficulties with the assessment is the lack of fast, reliable tools. Most questionnaires tend to overdiagnose. Clinicians also have difficulty assessing and interpreting comorbidity in personality disorders.

What difficulties does comorbidity cause?

If patients are identified as having between three and ten personality disorders, these are not separate disorders. Personality disorders are also comorbid with other mental disorders, such as depression or anxiety, so these disorders can dominate the clinical picture. However, personality disorders should not be seen as unimportant, as it may be one of the most important explanations for the recurrence of a disorder and difficulties in the treatment of a disorder. Yet, personality disorders are often forgotten as a target of treatment, often also because patients seek help for another clinical disorder and not for their personality disorder. In the DSM-5, the second axis of the DSM-IV has been removed because clinicians made too little use of it.

Which changes took place in the ICD-11?

A radical change in classification has been proposed for the ICD-11. The main difference between the ICD-11 and DSM-5 is that the ICD focuses on the severity of personality disorders and does not retain the categories. The ICD-11 bans all type-specific categories of personality disorders, except the presence of a personality disorder itself. This is seen as a continuum, with varying severity. The first step in the ICD-11 in diagnostics is to identify whether there is a personality disorder. The second step is to identify the severity. A category can also be assigned if it is relevant, and it refers to a disturbance that might be manifest only intermittently, in specific circumstances, or in specific environments. One of the benefits of the ICD is that it removes the confusing comorbidity between the personality disorders. The ICD has no age limit for diagnosis, so in theory it can already be used with children. A 'late onset' qualifier is added to the ICD-11. This is necessary, because some people only show the disorder if protective factors are withdrawn. This can increase the prevalence in ICD-11 compared with ICD-10. The proposals for the ICD-11 are being tested by the WHO.

BulletPoint Summary

• The core symptoms of personality disorders are: a pervasive pattern of maladaptive traits and behaviors that begin in early adult life and lead to significant personal distress and/or social dysfunction, and disruption to others.

• Diagnosing personality disorders is difficult. The disorder must be lifelong or at least of many years' duration and it must influence interaction with others. Another difficulty is that patients often do not recognize that they, and not others, are defective in their relationships.

• In the DSM-5, 10 different disorders are identified, in 3 different clusters. Cluster A includes the paranoid, schizoid and schizotypal categories. Cluster B includes the antisocial, borderline, histrionic and narcissistic categories. Cluster C includes the avoidant, dependent, and obsessive-compulsive categories. The three clusters are often used because there is a lot of comorbidity between the individual categories, which makes classification difficult, and because it is easier for researchers to consider 3 clusters than 10 disorders.

• Research in Western Europe and North America indicates a prevalence of personality disorders between 4 and 15%. It is just as common among men and women, and just as common among ethnic minorities as majority populations. Women are overrepresented in clinical settings, because of a higher help-seeking behavior.

• People with personality disorder have higher morbidity and mortality than those without, which can be explained by increases in suicide, homicide, unhealthy lifestyle behaviors and difficulties in relationships with care professionals.

• Few clinicians take the trouble to diagnose a personality disorder due to the complexity of the diagnostic system. However, there is also stereotyping, because people who show self-damaging behavior are almost automatically diagnosed with borderline and people who are aggressive and break the law are quickly diagnosed with antisocial personality disorder. One of the major difficulties with the assessment is the lack of fast, reliable tools. Most questionnaires tend to overdiagnose. 

• Other mental health disorders can dominate the clinical picture when they are comorbid with personality disorders. Moreover, patients often seek help for another clinical disorder. Yet, it is important personality disorders are recognized and treated, as they may be one of the most important explanations for the recurrence of a disorder and difficulties in the treatment of a disorder. 

• The main difference between the ICD-11 and DSM-5 is that the ICD focuses on the severity of personality disorders and does not retain the categories. The ICD-11 bans all type-specific categories of personality disorders, except the presence of a personality disorder. This is seen as a continuum, with varying severity. One of the benefits of the ICD is that it removes the confusing comorbidity between the personality disorders.