Amnesia

From Psy3242

Amnesia is a condition in which memory is disturbed. The causes of amnesia can be organic or functional. Organic causes include damage to the brain, through an injury or disease, or use of certain 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.

Although there are many types of amnesia, there are two main forms of it. Anterograde amnesia is where new events contained in the immediate memory are not transferred to the permanent as long-term memory. The sufferer will not be able to remember anything that occurs after the onset of this type of amnesia for more than a brief period following the event. Retrograde amnesia is the inability to recall some memory or memories of the past, beyond ordinary forgetfulness.

Other types of amnesia include:

• Korsakoff's syndrome: Memory loss caused by alcohol abuse. The person's short-term memory may be normal, but they will have severe problems recalling a simple story, lists of unrelated words, faces and complex patterns. This tends to be a progressive disorder and is usually accompanied by neurological problems, such as uncoordinated movements and loss of feeling in the fingers and toes. If these symptoms occur, it may be too late to stop drinking

• Traumatic amnesia: This follows brain damage caused by a severe non-penetrative blow to the head, such as in a road accident. It can lead to anything from a loss of consciousness for a few seconds to coma.

• Infantile/childhood amnesia: This refers to a person's inability to recall events from early childhood. There are many theories on this, for example, Freud put it down to sexual repression. Others say it could be linked to language development or the fact that some areas of the brain linked to memory are not fully mature

• Hysterical amnesia: This covers episodes of amnesia linked to psychological trauma. It is usually temporary and can be triggered by a traumatic event with which the mind finds it difficult to deal. Usually, the memory slowly or suddenly comes back a few days later, although memory of the trauma may remain incomplete.