Dissociative Amnesia

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Dissociative Amnesia, formerly Psychogenic Amnesia, is a dissociative disorder characterized by an inability to remember personal information, usually including traumatic events but at times also including identity information such as one's name or family. This loss of recollection causes serious distress in social and daily functioning.

Memories lost in dissociative amnesia are capable of being retrieved. Individuals with dissociative amnesia are frequently mostly or completely unaware of their amnesia before it is pointed out to them and attempt to minimize the severity. Histories of trauma are common among those with dissociative amnesia. Dissociative amnesia can be experienced as part of another disorder.

1.8% of the US population has dissociative amnesia.

Types
Localized amnesia involves the inability to recall certain events for a limited period of time after they occur, usually for a few hours after a traumatic or otherwise stressful event but at times lasting for days after.

In selective amnesia, the individual can recall some but not all parts of the event, still usually within the same general circumstances and time frame as localized.

Generalized amnesia is "a complete loss of memory of one's life history," including personal identity, semantic knowledge, and skills. The disorientation in generalized amnesia is typically visible enough for emergency services to become notified of the occurrence. Total amnesia is most common in victims of childhood sexual abuse, ranging from 19 to 38 percent.

Continuous amnesia is the inability to recall the events leading up to a particular time, including leading up to the present.

Systematized amnesia is the loss of memories within a certain subject category, such as of a family member.

Memory Recovery
In a study done in the early 1970s, 206 girls ages ten to twelve who had been admitted to hospitals because of sexual abuse were interviewed about their memory of it. Seventeen years later, 136 of them were able to be tracked down and were again interviewed. Only 62% of the women remembered the abuse, and 16% reported forgetting it before remembering it again. All of the descriptions given by those who had recovered their memories were accurate on central details, but none of their stories lined up perfectly. Neuroscience research has reinforced this, showing that retrieved memories return to the memory bank with modifications.

Memories can be recovered spontaneously, when the traumatic or stressful situation ends, or over long periods of time. Recovery can be extremely stressful and temporarily increase other PTSD symptoms.

Controversy
Research has shown that it is easy to implant memories of events that never took place, but none of these will be accompanied by the emotions associated with them. The memories are often only partial, and the subject is able to explain them in less detail than "true" memories. These false memories would be created through "leading questions and excessive insisting." Alternatively, memories lost of trauma are argued to have been lost through the normal process of forgetting.