Jumbo Ring Memory Sculpture, 2016
 
Amnesia, also called amnestic syndrome, is a loss of memories, such as facts, information and experiences, according to the Mayo Clinic. Unlike a temporary episode of memory loss, amnesia can be permanent. However, though losing one's memory of identity — not knowing who you are — is a common plot device on soap operas and mysteries, amnesia does not usually cause a loss of self-identity. Instead, people with amnesia usually know who they are, but they have trouble with short-term memory; they can't learn new information or form new memories.
Amnesia can occur as a result of head trauma, drug toxicity, stroke, Alzheimer's disease, infection or even emotional shock. This last type is called dissociative amnesia and is classified as psychogenic, or as having a psychiatric origin, and can result in the temporary loss of personal memories and identity.
These memories can often be recovered through psychotherapy, but in cases where amnesia lasts for months or years, the subject may begin an entirely new life. This is called a fugue state, and if those affected didn’t have it hard enough, on recovering their memories of pre-trauma events they usually forget the fugue state!