The following extracts from the World Psychiatric Association and International Society for the Study of Personality Disorders resource ‘Educational Program on Personality Disorders’ is intended to answer some important questions on the complex issue of personality disorders.

What are Personality Disorders?

The Oxford Dictionary defines personality as the combination of characteristics or qualities that form an individual’s distinctive character. For psychologists, personality is the individual’s distinctive pattern of perceiving, feeling, thinking, coping, and behaving. The adult personality is essentially formed by late adolescence. 

Personality disorders (PDs) are conditions in which there is persistent abnormal behaviour and attitudes that create distress and social dysfunction, and that cannot be attributed to the presence of a mental state disorder. PDs have been estimated to affect at least 10% of the population, and constitute a large percentage of the patients seen by psychiatrists. Unlike other diagnoses, PDs may or may not be associated with subjective symptoms.

Two classificatory systems of mental disorders are recognized internationally today, namely, the Diagnostic and Statistical Manual of Mental Disorders (DSM) and the International Classification of Mental and Behavioural Disorders (ICD). Personality disorders are given important weight in both classifications. The two classification systems are similar but many issues of definition and classification remain subject to intense debate.

Are there hard and fast boundaries between different personality disorders, and between personality disorders and normal psychology?

This question is not an easy one to answer. The difficulties psychiatrists face in attempting to classify personality disorders can be seen in the three different shema that are currently used to conceptualise personality disorders.

The first way to conceptualise a personality disorder is through the use of diagnostic categories. Someone would be diagnosed as having narcissistic personality disorder, for example, if they exhibit the list of characteristics which define that disorder e.g. grandiose sense of self-importance, a strong need for admiring attention, unwilling to recognize or identify with the feelings and needs of others, having a sense of entitlement, and having tendencies to be exploitive and take advantage of other people, etc. One advantage of an established system of categories is that assignment to a particular category can alert the clinician to a range of unobserved but frequently correlated behaviours that might otherwise have been missed.

Opponents of the categorical model however argue that categories assume the existence of discrete boundaries between categories and between normality and abnormality. The main alternative to the use of categories have been so called dimensional models. These models, rather than using a check list of characteristics which must all be present, combine numerous clinical features or personality traits to build up a personality profile. Rather than “forcing” patients into categories into which they may not quite fit, dimensional models are more flexible, and can better reflect individual differences. In contrast to categories, dimensional schemas also allow for degrees of normality / abnormality, rather than clear categorical distinctions.

A third model, the prototypal model, has emerged in recent years as synthesis of both of the previous models. A prototype consists of the most common features of members of a category, and provides a standard against which people can be evaluated. No actual person might match the theoretical prototype perfectly. Instead different people will approximate it to different degrees. The prototype model combines the grouping of characteristics of the categorical model with the flexibility of the dimensional model. Prototypal models seem to reflect more accurately the complexity of personality disorders and may become the preferred schema for representing PDs.

Are Personality Disorders Caused by Nature, Nurture or Both?

Behavioural genetic research demonstrates that about 40-50% of the variance between individuals in personality traits is attributable to genetic factors. PDs show similar levels of heritability. Genetic factors in personality can sometimes be apparent early in life. For example, longitudinal studies of children have established that antisocial personality can be predicted by observations of aggressive temperament as early as age three. However while heredity certainly plays a role in PD development, genetics is not destiny. Other factors also play major roles in the development of personality disorders.

Psychologists have long known that the circumstances of daily family life have an enduring and cumulative effect upon the entire fabric of the child’s development. Within this setting the child establishes a basic feeling of security, imitates the ways in which people relate interpersonally, acquires an impression of how others perceive and feel about him, develops a sense of self-worth and learns how to cope with feelings and the stresses of life. Chronic dysfunction in the home environment can have a marked effect on personality development. Patients with certain PDs frequently come from dysfunctional families, which are often marked by abuse and neglect.

Yet once again, family need not be destiny. It has been repeatedly shown that most children demonstrate a remarkable level of resilience to a wide range of adversities. For this reason, the impact of life events can only be understood through their interaction with the individual temperamental vulnerability of the child.

Culture also appears to play a major role in the development of personality disorders. For example, antisocial PD is very common in some countries, and relatively rare in others. Antisocial PD has also become increasingly frequent in Western societies in recent decades.

How are Personality Disorders Assessed?

The three most widely used methodologies for assessing personality disorders are clinical interviews; rating scales and checklists; and self-report inventories.

Interviews are carried out by clinicians using structured questionnaires. Examples of structured interviews include the International Personality Disorders Evaluation (IPDE) interview that was developed by the World Health Organization [1], and the DIN, designed specifically to assess narcissistic personality disorder [2].

Checklists and ratings scales can be completed by anyone who knows the subject well, and again are most often completed by  the clinician. The most widely used rating scale is the revised Psychopathy Checklist (PCL-R) [3], which is used to diagnose psychopathy. Although the PCL-R is widely used in the study of psychopathy, few rating scales exist for use with other PDs.

Self-report inventories are questionnaires designed to be completed by the patient themselves. One widely used self-report inventory is the Personality Diagnostic Questionnaire [4].

These instruments are most often used in combination to diagnose personality disorders.

Do Personality Disorders Change over a Lifetime?

The question as to whether personality disorders remain stable or change over time is a controversial one. Evidence suggests that narcissistic and paranoid personality disorder seem to remain stable, or even worsen with age. While life events can both improve and worsen narcissistic personality functioning, other personality disorders, such as paranoid personality disorder appear to be less influenced by external events.

Can Personality Disorders be Treated?

Two major “psychological therapies” are the dominant approaches for the treatment of personality disorders worldwide – psychodynamic therapies and cognitive therapies. While the two techniques differ in their approach, they both aim to modify the dysfunctional beliefs and behaviours that characterise personality disorders. Since the beliefs and behaviours that characterise personality disorders however are extremely rigid and persistent, the effectiveness of psychological therapies is variable.

Medication is often used as a complementary intervention alongside psychological therapy in the treatment of personality disorders. It is well know that personality disorders and other psychiatric disorders often co-exist. Research shows that anxiety, depression, eating disorders, substance abuse, and sexual disorders occur more often in the context of personality disorders. In most cases medication reduces specific symptoms of the disorder, such as anxiety or aggressiveness, but does not affect the core features of the disorder.

1. Loranger, A.W. (1999) International Personality Disorders Examination Manual: DSM-IV Module. Washington D.C.: American Psychiatric Press.

2. Gunderson, J.G., Ronningstam, E., & Bodkin, A. (1990). The diagnostic interview for narcissistic patients. Archives of General Psychiatry, 47(7), 676–680.

3. Hare, R.D. (1991). The Hare psychopathy checklist–revised manual. Toronto: Multi-Health Systems.

4. Hyler, S.E., & Rieder, R.O. (1987). PDQ-R: Personality diagnostic questionnaire-revised. New York: New York State Psychiatric Institute.

Link to the ISSPD XIII International Congress on the Disorders of Personality