Multiple Personality Disorder

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.https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4695775/ 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.https://doi.org/10.1176/ajp.145.10.1301 "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."https://dsm.psychiatryonline.org/doi/book/10.1176/appi.books.9780890420188.dsm-iii-r
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.
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== 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.https://books.google.com/books?id=YBSqjV6wFQQC&pg=PA473 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.
Besides 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. 
Category:Psychiatric Terms
Category:Dissociation-Related Terms
Category:Disorder-Related Terms