Multiple Personality Disorder

undefined:Multiple Personality Disorder (MPD) is a dissociative disorder appearing by that name only in the DSM-III and some editions of the ICD, including the ICD-10 but not the ICD-11. MPD replaced a Hysterical Neurosis diagnosis and was replaced with Dissociative Identity Disorder. The main characteristic of MPD is the existence of two or more personalities in one body that were dominant at different times. Each personality is a "complete" individual, with unique memories and behaviors. Switching is typically sudden and stressful.

The original (or host) is usually unaware of the other personalities, but if there are more than two personalities within the body, the others are aware of each other to some extent. While only one personality can speak at a time, others can "listen in" at times. All personalities are aware of the loss of time, but they may not acknowledge it unless asked. Personalities tend to present as opposites, and there is usually a dominant personality.

Other personalities can sometimes have mental disorders that the original does not. They may be of a different sex or gender, a different race, or be from a different family. They will behave as the age they say they are, which is typically younger than the body's age. Personalities might report having heard voices or interacted with other personalities, both of which are differentiable from hallucinations and delusions. When occurring in groups, as is common, sometimes a personality will be a protector for another personality. Most personalities have their own names, sometimes including a different last name from the body's name, but occasionally they will be unnamed or share the original's name.

Criteria
The DSM-III diagnostic criteria for MPD is defined as such:

A. The existence within the individual of two or more distinct personalities, each of which is dominant at a particular time.

B. The personality that is dominant at any particular time determines the individual's behavior.

C Each individual personality is complex and integrated with its own unique behavior patterns and social relationships.

The ICD-10 criteria for MPD:

A. The existence of two or more distinct personalities within the the individual, only one being evident at a time.

B. Each personality has its own memories, preferences and behaviour patterns, and at some time (and recurrently) takes full control of the individuals behaviour.

C. Inability to recall important personal information, too extensive to be explained by ordinary forgetfulness.

D. Not due to organic mental disorders (e.g. in epileptic disorders) or psychoactive substance-related disorders (e.g. intoxication or withdrawal).

Personality vs. Identity
Multiple Personality Disorder was changed to Dissociative Identity Disorder for a few reasons. The first is that MPD had an emphasis on the idea of systems having many personalities, rather than being the lack of a single, cohesive personality, as plurality is believed to be by many in the medical field. The second is the meaning of "personality" in the field of psychology, being "characteristic patterns of thoughts, feelings, moods and behaviors of the whole individual," without accounting for identity aspects or the fact that a system is not considered a "whole" individual. The DSM-IV also claimed that personalities did not have their own objective existences and were simply named and identified by the patient.

Despite these reasons, DID is considered by many to be a more sensitive term, as "identity" is more respectful to alters' unique existences than "personality," which is seen as implying that they are nothing more than a different state of the original. MPD should not be used as an identifier for systems without their consent.