what is it called when someone has split personalities
Dissociative identity disorder Dissociative identity disorder (DID), also known as multiple personality disorder,[5] is a mental disorder characterized by at least two distinct and relatively enduring personality states.[1] There is often trouble remembering certain events, beyond what would be explained by ordinary forgetfulness.[1] These states alternately show in a person's behavior.[1] Presentations, however, are variable.[3] Associated conditions often include borderline personality disorder, post traumatic stress disorder, depression, substance misuse disorder, self-harm, or anxiety.[1][3]