Dissociative amnesia

Dissociative amnesia or psychogenic amnesia is 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.

Dissociative amnesia was previously known as psychogenic amnesia, a memory disorder, which was characterized by sudden retrograde episodic memory loss, said to occur for a period of time ranging from hours to years to decades.

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 should be evident but some form of psychological stress should precipitate the amnesia. Psychogenic amnesia as a memory disorder is controversial.

Source: Wikipedia