Amnesia is a medical condition which affects the brains ability to recall memory information. The symptoms of amnesia can be caused by a variety of different reasons. Some of these reasons include brain damage, traumatic events, or even the use of certain drugs. Amnesia can vary in degrees of severity from very mild to complete loss of memory. In order to answer the question, “What is amnesia?” you must look at a patient’s symptoms and the types of memories they have lost. There are also different types of amnesia. These varying types are based on the types of memory which have been lost. One definition of amnesia does not fit all types of memory loss. To define amnesia doctors must look carefully at what a patient can and can not recall. An amnesia definition can generally be stated as a loss of memory, but there is much more to amnesia than that.
Anterograde Amnesia Definition
Anterograde amnesia is also commonly called selective memory loss. This type of amnesia can result from brain injuries that are so severe that a person is impaired from learning new information. In most cases, individuals suffering from anterograde amnesia retain most of the memory information that they had stored before their injury. However, things which occur following the injury seem to be lost. These symptoms manifest themselves in an ability to recall quite well memories from childhood, but an inability to remember events which have happened very recently or things which took place following the injuries. Usually, when a person suffers from this type of amnesia, their short term memory remains intact, so that they would be able to have a conversation, however, as soon as the individual is distracted he would no longer be able to remember that same conversation.
One interesting aspect of this type of amnesia is that although memory for facts and events has been devastated, it would appear that memory focusing on skills and habits still remains functional. This means that the individual can be taught new skills. In most cases they will not remember being taught the skill, but they will still remember how to execute the skill. This has become an important area of research as doctors and scientists wish to study these individuals in order to learn exactly how memories are formed. This type of research can then in the future help other amnesic patients.
Anterograde amnesia generally occurs after there has been significant damage to three distinct brain areas. The first area, which has also been studied the most, is the hippocampus along with its associated areas in the medial temporal lobes. This area of the brain is believed to act like a gateway for new information so that it can be permanently stored. When this area is damaged, it seems as if new information can not be entered as a memory. This would explain why the older information, which has already passed through the gateway, remains stored.
Damage to the hippocampus has been associated with strokes and aneurysms occurring in one of the arteries responsible for supplying blood to these areas. Other causes of damage can be epilepsy, encephalitis, carbon monoxide poisoning, near drowning, near suffocating and Alzheimer’s. There is also proof that normal aging can cause some damage to the hippocampus.
Retrograde amnesia is one of the types of amnesia which can also result from a brain injury. In individuals who suffer from this type there is loss of memories just before the injury. The time frame in which these memories can originate can span from a few minutes up to many years. In most cases the events which happened right before the injury are the memories most permanently lost.
On rare occasions there are reported incidents where an individuals may experience pure retrograde amnesia caused by a brain injury. However, what is most often the case, is that an individual experiences retrograde amnesia as part of their anterograde amnesia. In those cases the person has lost nearly all of their memories for events which occurred after the injury, and there may be some memory loss for events which occurred prior to the injury. Much research is still ongoing into retrograde amnesia psychology.
Transient Global Amnesia
Because there are so many different types of amnesia, it is hard to list exactly what causes amnesia. There are different causes for different types. Transient global amnesia is a type of amnesia in which there is a sudden temporary incident of memory loss which can not be attributed to any usual neurological conditions like epilepsy or stroke.
An episode of this kind of amnesia would be characterized by the vanishing of very recent events also called selective amnesia. For instance a person may not be able to remember where they are or how they got there. Another symptom is the inability to know what is going on at the moment. Individuals suffering from an incident like this may ask the same questions over and over even though the question has already been answered. Some people suffering from this will also have a hard time remembering what happened a day ago or a week ago.
Individuals suffering from transient global amnesia remember who they are, and who others are, however, the memories which are lost is still very disturbing. This type of amnesia is rare and the incidents are usually short lived and does not affect long term memory. This is a form of short term amnesia.
Psychogenic amnesia is a type of amnesia disorder which many people label as functional amnesia. This condition has also been called dissociative amnesia. People suffering from this will have abnormal memory function as part of their dissociative amnesia symptoms even though there is no structural brain damage. This type of amnesia is caused by severe stress or a psychological trauma not physical injury. In this past this condition was called repressed memory syndrome.
The two main types of psychogenic amnesia are global and situation specific. Global entails a sudden loss of identity which can last a few hours or a few days and involves extreme confusion. Situation specific is a kind of psychogenic amnesia that relates specifically to an extremely stressful event and is usually part of post traumatic stress disorder.
A dissociative amnesia definition is often hard to pinpoint because there can be many ways in which this condition manifests itself. Most people classify this as traumatic amnesia, but there is still much research to be done to determine why the brain will react to traumatic events this way. This is usually a type of temporary amnesia. This is the best way to define dissociative amnesia.
Infantile Amnesia Definition
Infantile amnesia also known as childhood amnesia, is the phenomenon in which adults have a very hard time retrieving memories from before age four. What is so interesting about this type of amnesia is that, it results without any damage to the brain or traumatic events. Research which has been done on very young children proves that before age five most children can recall memories as early as one year old. However, these memories begin to fade as the child gets older. One possible reason for this is that the hippocampus, which is responsible for memory storage in our brains, is not fully developed in very young children. So when the hippocampus does continue to develop some of the memories which had already been formed are lost. However, many adults can still recall a few memories from their earliest childhood, but generally not before about age two.
Post Hypnotic Amnesia
Posthypnotic amnesia is the term used to describe the state that an individual is put in following a hypnotism session. Generally a participant will not be able to recall any memories or events that took place during the session. It is believed that this is because while under hypnosis the individual has had their memory retrieval and creation areas of the brain “relieved of duty” to speak. The hippocampus is affected during hypnosis in such a way that when the individual comes out of hypnosis they have not recollection of what took place.
Cultural amnesia is not an amnesia disorder at all, but rather a social term used to describe the process of a group of people, be it racial, religious or otherwise, who over time lose sight of the traditions, practices or beliefs that once defined them. Cultural amnesia is seen most significantly in groups that help to very strict or very obviously counter mainstream beliefs and practices. You can see examples of cultural amnesia when you hear certain members of these groups refer to “the good old days.” Cultural amnesia has nothing to do with a human’s brain function, but rather to an entire group’s behaviors and choices over a span of time.
Proactive amnesia, also called proactive interference is the practice of interfering with the retrieval of old memories with the creation of new memories. The theory is that the working memory can over ride the existing memory in order to help individuals change old habits and behaviors, but bombarding the mind with newer better activities, information and knowledge. The brain struggles to dwell on the old, harmful memories that could be causing individuals pain or depression. The new, happier memories flood in and take over for a while. This type of therapy provides relief to individuals suffering from depression or suicidal tendencies.
Although causes of amnesia are still being researched, individuals who are suffering from the various forms of amnesia have many treatment options available to them. There are also some experimental drugs which hopes to assist in the treatment and recovery of amnesia patients. Even though amnesia is a disturbing and troubling condition, most individuals who experience it in its different forms, are usually able to carry on with their lives with some degree of normalcy.
The important thing to remember when dealing with a person who is suffering from amnesia, is to be kind, compassionate and patient as they attempt to navigate their new and often times confusing world. Recovering from amnesia takes time and in most cases much therapy both for the emotional effects of amnesia and for practical memory retrieval exercises.