Psychogenic amnesia, or dissociative amnesia, is a  memory disorder characterized by sudden retrograde autobiographical memory loss, said to occur for a period of time ranging from hours to years. More recently, "dissociative amnesia" has been defined as a dissociative disorder "characterized by retrospectively reported memory gaps. These gaps involve an inability to recall personal information, usually of a traumatic or stressful nature." In a change from the DSM-IV to the DSM-5, dissociative fugue is now subsumed under dissociative amnesia.