Multiple Personality Disorder

undefined:Multiple Personality Disorder (MPD) is a dissociative disorder appearing by that name only in the DSM-III (1980 to 1994) 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. "In classic cases, there are at least two fully developed personalities; in other cases, there may be only one distinct personality and one or more personality states."

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.

Diagnostic History
Multiple Personality Disorder appeared only in two published editions of the DSM, those being the original publication of the DSM-III in 1980 and the DSM-III-R in 1987. The next edition was the DSM-IV in 1994, at which point the diagnosis was formally changed to Dissociative Identity Disorder. It was classified under the category of "Dissociative Disorders (or Hysterical Neuroses, Dissociative Type)" with the code of 300.14. It was rarely diagnosed until adolescence and most recipients were female.

In the 1987 revision, it was stated that recent studies showed that MPD was less rare than commonly thought to be, almost always predisposed by abuse (often sexual) or other severe emotional trauma in childhood, and three to nine times more likely to be diagnosed in females than in males. A group responsible for reviewing the changes to dissociative disorders explained that while the diagnosis was controversial, they needed to provide the most recent findings to provide more basis for opinion. They described the changes and reasonings in great detail in an issue of Dissociation. Since 90% of psychiatrists used the DSM-III-R by the second year of its publication, it's safe to assume that diagnoses made between 1988 and 1994 were almost always determined by the revised criteria.

When the DSM-III was published in 1980, it referenced MPD as falling under the ICD category "Neurotic Disorders, Personality Disorders, and Other Nonpsychotic Mental Disorders." A 1998 version of the ICD-10 listed MPD in an "others" category, F44.80. By 2018, Dissociative Identity Disorder had the code of F44.81.

A 1990 issue of the medical journal Dissociation expressed concern about the potential removal of MPD as a unique diagnosis in the ICD-10, instead classifying it under an "Other" diagnosis, which was theorized to be due to psychiatric disbelief in Europe. The doctor responsible proposed a diagnosis of "Multiple (Dissociated) Personality Disorder," falling under the category of Dissociative Disorders, so it could "reflect the worldwide occurrence separate from the nonpathological trance/possession states."

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 DSM-III-R criteria for MPD:

A. The existence within the person of two or more distinct personalities or personality states (each with its own relatively enduring pattern of perceiving, relating to, and thinking about the environment and self).

B. At least two of these personalities or personality states recurrently take full control of the person's behavior.

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.