Amnesia

Amnesia (from Greek Ἀμνησία) (see spelling differences) is a condition in which memory is disturbed. The causes of amnesia are organic or functional. Organic causes include damage to the brain, through trauma or disease, or use of certain (generally sedative) drugs. Functional causes are psychological factors, such as defense mechanisms. Hysterical post-traumatic amnesia is an example of this. Amnesia may also be spontaneous, in the case of transient global amnesia. This global type of amnesia is more common in middle-aged to elderly people, particularly males, and usually lasts less than 24 hours.

Another effect of amnesia is the inability to imagine the future. A recent study published online in the Proceedings of the National Academy of Sciences shows that amnesiacs with damaged hippocampi cannot imagine the future. This is because when a normal human being imagines the future, they use their past experiences to construct a possible scenario. For example, a person who would try to imagine what would happen at a party that would occur in the near future would use their past experience at parties to help construct the event in the future.

Amnesia is prevalent in many works of fiction. Global amnesia is a common motif in fiction despite being extraordinarily rare in reality. Anterograde amnesia features in the movies Memento, Clean Slate, and 50 First Dates, and lacunar amnesia features in the movie Eternal Sunshine of the Spotless Mind. In the first season of 24, a prominent character has dissociative amnesia. In the first season of Lost, a character is kidnapped and has amnesia upon returning. The TV show John Doe is based on an amnesiac who mysteriously appears in the middle of a sea. In The Bourne Identity, the main character has retrograde amnesia. In the 1966 motion picture Mr. Buddwing, the protagonist enters an amnesial fugue state in response to distress in his marital relationship. In the 2004 film The Forgotten, adults struggle with memory loss about the existence of their children, who have been abducted for alien/government experiments. In the Marvel Comics series X-Men, Wolverine, one of the main characters, has retrograde amenesia due to brainwashing. In Season 4 of Smallville, Clark has his memory wiped by a Summerholt patient.

In Century Fox's animated film, Anastasia (1997), Anya suffers from amnesia as a result of having her head hit when trying to climb on train to escape to Paris with her grandmother as a young girl and cannot recall the first eight years of her life, and sang "Once Upon A December" & "Journey to the Past", to refresh memories of being a Russian princess and her family, the Romanov family.

In movies and television, particularly sitcoms, it is often depicted that a second hit to the head (similar to the first one) cures the amnesia. In reality, however, a second concussion would have catastrophic consequences, a phenomenon known as Second Impact Syndrome. Dissociative Amnesia plays a critical role in the novel Mysterious Skin and movie of the same name. Author Gene Wolfe addresses amnesia in the series Soldier of the Mist, where the main character Latro is injured during battle, causing relatively long term (24 hour) anterograde amnesia.

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