Psychogenic amnesia or dissociative amnesia is a memory disorder characterized by sudden retrograde episodic memory loss, said to occur for a period of time ranging from hours to years to decades. 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. The atypical clinical syndrome of the memory disorder (as opposed to organic amnesia) is that a person with psychogenic amnesia is profoundly unable to remember personal information about themselves; there is a lack of conscious self-knowledge which affects even simple self-knowledge, such as who they are. Psychogenic amnesia is distinguished from organic amnesia in that it is supposed to result from a nonorganic cause: no structural brain damage or brain lesion should be evident but some form of psychological stress should precipitate the amnesia, however psychogenic amnesia as a memory disorder is controversial. Definition Psychogenic amnesia is the presence of retrograde amnesia (the inability to retrieve stored memories leading up to the onset of amnesia), and an absence of anterograde amnesia (the inability to form new long term memories). Access to episodic memory can be impeded, while the degree of impairment to short term memory, semantic memory and procedural memory is thought to vary among cases. If other memory processes are affected, they are usually much less severely affected than retrograde autobiographical memory, which is taken as the hallmark of psychogenic amnesia. However the wide variability of memory impairment among cases of psychogenic amnesia raises questions as to its true neuropsychological criteria, as despite intense study of a wide range of cases there is little consensus of which memory deficits are specific to psychogenic amnesia. Past literature has suggested psychogenic amnesia can be 'situation-specific' or 'global-transient', the former referring to memory loss for a particular incident, and the latter relating to large retrograde amnesic gaps of up to many years in personal identity. The most commonly cited examples of global-transient psychogenic amnesia are 'fugue states', of which there is a sudden retrograde loss of autobiographical memory resulting in impairment of personal identity and usually accompanied by a period of wandering. Suspected cases of psychogenic amnesia have been heavily reported throughout the literature since 1935 where it was reported by