Mental health articles

Currently personality disorders are diagnosed by the recognition of a set of diagnostic criteria. Within both DSM-IV  and ICD-10 personality disorders are described as a mixture of both psychological traits and overt behaviours. Each diagnostic system describes the concept of personality disorder upon which subsequent specific diagnoses should be based. DSM-IV describes a personality disorder as ‘an enduring pattern of inner experience and behaviour that deviates markedly from the expectations of the individual’s culture, is pervasive and inflexible, has an onset in adolescence or early adulthood, is stable over time, and leads to distress or impairment’.

The specific personality disorders are then grouped into three clusters based on descriptive similarities. Cluster A disorders are described as ‘odd or eccentric’, Cluster B as ‘dramatic, emotional, or erratic’, and Cluster C as ‘anxious or fearful’. However, this clustering system has been found to have limited validity, although has been useful in some research and educational situations (Tyrer 2000). As can be seen in Table 21.1, ICD-10 and DSM-IV differ in their classification and description of specific personality disorders. Psychological traits such as sensitivity and impulsivity mixed with descriptions of behaviour such as violence and self-harm, have led to discussions as to whether these diagnoses reflect true personality disorders or are actually descriptions of social deviance. Each diagnostic system agrees that a diagnosis of personality disorder can only be made where the psychological traits and/or behaviours have been present since adolescence or early adulthood. Clearly then, a marked change in behaviour or personal characteristics, in response to a specific situational stressor cannot be included as evidence of the presence of a personality disorder. Similarly the behaviours and/or traits should permeate the whole of the person’s experience; in other words, personality disorders cannot be active or inactive dependent on circumstances. Importantly, only when the identified traits and/or behaviours cause significant functional impairment or subjective distress can a diagnosis of personality disorder be made. The traits and behaviours displayed by a person with a diagnosis of personality disorder will commonly lead to difficulties in developing and maintaining close relationships or holding down regular employment.

For a firm diagnosis of personality disorder within ICD-10, the patient must fulfil a set of specified criteria. However, within the DSM-IV classification system a set of criteria are provided of which the person must meet a number, but not all, for a positive diagnosis to be made. As such the system of diagnosis as set out by DSM-IV can lead to a number different combinations of traits and behaviours resulting in the same diagnosis. For example, it has been calculated that there are 848 different combinations of criteria that can construct a diagnosis of anti-social personality disorder, and 247 combinations to meet criteria for borderline personality disorder.

Tags: classification, diagnosis, disorders, personality, personality disorders