Definition

The study of the personality disorders has been beset by problems, and, as a result, the use of such diagnoses is often questioned. The World Health Organisation defines these conditions as comprising “deeply ingrained and enduring behaviour patterns, manifesting themselves as inflexible responses to a broad range of personal and social situations.”

They are associated with ways of thinking, perceiving, and responding emotionally that differ substantially from those generally accepted within a patient's culture. As a result, patients tend to exhibit a severely limited repertoire of stereotyped responses in diverse social and personal contexts. These patterns are usually evident during late childhood or adolescence, but the requirement to establish their stability and persistence restricts the use of the term “disorder” to adults.

Classification

There are two main approaches to classification—dimensional and categorical.

Dimensional classification—This defines the degree to which a person displays each of a number of personality traits and behavioural problems. This approach is proving useful in investigating the biochemical underpinnings of many of these disorders.

Categorical classification—This, the basis of the major clinical systems for classifying mental disorders, assumes the existence of distinct types of personality disorder …