Multiple Personality Disorder (MPD) is a dissociative disorder. Dissociation is the "separation of an idea or thought process from the individual's ongoing consciousness or awareness" (Merit Students 576). MPD is the most extreme type of dissociative disorder. It is defined as existence within a person of two or more separate and distinct personalities, each having it's own behavior patterns, social relationships, and life history. The personality that is dominant at a particular time determines the person's behavior.
MPD has many symptoms. Some are: depression, insomnia, sleepwalking, nightmares, flashbacks, auditory and visual hallucinations, eating disorders, trances, headaches, out of body experiences, alcohol and drug abuse, compulsions, violence both self-inflicted and directed outward. People experience changes in their behavior and mannerism, changes in right and left handedness, they may show differences in their handwriting, responses to medication , allergic reactions, and eyeglass prescriptions. The Changes depend upon which personality is dominant.
No one actually knows what causes DID(MPD), but doctors and scientists have come up with possible causes for the disorder. Some of these are severe emotional, sexual, and physical abuse. However being abused is not enough to cause DID(MPD), the person "Must also have an inborn capacity to dissociate" (Merit Students 577). A severe trauma such as emotional stress or an injury may cause a person to lose part of their memory in order to erase the painful experience from their mind. As incidents of abuse keep happening over time and are interchanged with incidents of love and nurturing, these memories become linked together and form the basis that allows DID(MPD) to develop in a person. It is thought to develop in a person's childhood, but the symptoms normally do not show up or are not recognized and treated until later in a person's life.
