Dissociative identity disorder (
DID), previously known as
multiple personality disorder (
MPD), is a
mental disorder on the dissociative spectrum characterized by the appearance of at least two distinct and relatively enduring
identities or dissociated
personality states that alternately control a person's behavior, accompanied by memory impairment for important information not explained by ordinary forgetfulness. These symptoms are not accounted for by
substance abuse,
seizures, other medical conditions, nor by imaginative play in children. Diagnosis is often difficult as there is considerable
comorbidity with other mental disorders.
Malingering should be considered if there is possible financial or forensic gain, as well as
factitious disorder if help-seeking behavior is prominent.