Dissociative identity disorder
Dissociative identity disorder (DID), previously known as multiple personality disorder (MPD), is a mental disorder characterized by the maintenance of at least two distinct and relatively enduring personality states. The disorder is accompanied by memory gaps beyond what would be explained by ordinary forgetfulness. The personality states alternately show in a person’s behavior; however, presentations of the disorder vary. Other conditions that often occur in people with DID include post-traumatic stress disorder, personality disorders (especially borderline and avoidant), depression, substance use disorders, conversion disorder, somatic symptom disorder, eating disorders, obsessive–compulsive disorder, and sleep disorders. Self-harm, non-epileptic seizures, flashbacks with amnesia for content of flashbacks, anxiety disorders, and suicidality are also common.
DID is associated with overwhelming traumas, or abuse during childhood.:294 In about 90% of cases, there is a history of abuse in childhood, while other cases are linked to experiences of war, or medical procedures during childhood. Genetic and biological factors are also believed to play a role. The diagnosis should not be made if the person’s condition is better accounted for by substance abuse, seizures, other mental health problems, imaginative play in children, or religious practices.
Treatment generally involves supportive care and psychotherapy. The condition usually persists without treatment. It is believed to affect about 1.5% of the general population (based on a small US community sample) and 3% of those admitted to hospitals with mental health issues in Europe and North America. DID is diagnosed about six times more often in females than males. The number of recorded cases increased significantly in the latter half of the 20th century, along with the number of identities claimed by those affected.
DID is controversial within both psychiatry and the legal system. In court cases, it has been used as a rarely successful form of the insanity defense. It is unclear whether increased rates of the disorder are due to better recognition or sociocultural factors such as media portrayals. The typical presenting symptoms in different regions of the world may also vary depending on culture, for example alter identities taking the form of possessing spirits, deities, ghosts, or mythical figures in cultures where normative possession states are common.:295,801 The possession form of dissociative identity disorder is involuntary, distressing and occurs in a way that violates cultural or religious norms.: