amnesia is a disorder that affects the normal functioning of memory and makes the sufferer unable to store information or retrieve it correctly.
However, beyond this superficial definition there are many nuances that make us have to talk, more about amnesia as a global concept, about types of amnesia.
Amnesia can take different forms
Amnesia can present itself in so many forms that studies of certain lesions and dysfunctions in different parts of the brain have led to the discovery of the mechanisms that operate behind the use of memory from the different types of amnesia that present themselves.
In addition, this phenomenon may be caused by injuries or by the “emotional imprint” left on the brain by certain experiences, causing some memories to be blocked. This makes that the types of amnesia can also be established by attending to the different causes that produce them. In this way, it has been seen that what seems to be a simple cognitive function based simply on the storage of information is, in reality, the result of several processes that work at the same time.
In this article we will show the different types of amnesia, their characteristics and criteria by which they can be classified into different categories .
1. Types of amnesia according to their chronology
If we look at the criterion of the chronology in which the amnesia manifests itself, we will distinguish between two types of amnesia: the retrograde and the antegrade . This classification only serves to describe the symptoms of amnesia, and does not give information about what causes it. Furthermore, both types of amnesia can occur at the same time, although often one is more noticeable than the other.
In retrograde amnesia the unremembered experiences happened before the disorder began to develop . It is the best known type of amnesia and is reflected in series, films and other works of fiction in which a character does not remember a part of his past.
1.2. Antegrade amnesia
In this type of amnesia , there is a total or partial inability to make the experiences that one is living through remain fixed in one’s memory . In other words, anterograde amnesia, by affecting what has been happening since the disorder first developed, means that what is being experienced does not become part of the long-term memory and is forgotten after a few minutes or seconds.
An example of this type of amnesia can be seen in the famous film Memento.
2. Types of amnesia according to their causes
2.1. Global Amnesia
This type of amnesia consists of total loss of memory , although normally the most important memories related to one’s identity will be preserved. Among its most likely causes is the possibility that a traumatic event has altered the normal functioning of the brain.
2.2. Childhood Amnesia
It consists of the inability to remember events experienced in childhood . Despite its name, this type of amnesia is not considered a disorder, as it is common and part of the normal development of the nervous system as you grow up.
2.3. Drug-induced amnesia
A type of amnesia produced by the administration of substances that affect the functioning of the brain by causing people not to remember the events that are happening at that time. It may be a side effect of a drug or it may be the purpose for which a substance has been given for therapeutic purposes during, for example, surgery.
2.4. Transitional global amnesia
It is not known what causes this type of amnesia, only its symptoms. The person experiencing transient global amnesia will remember the essential aspects about his or her identity and will also be able to remember things about the immediate past, but will have difficulty accessing memories about what happened just a few minutes ago (anterograde amnesia) and possibly also remembering some things pertaining to long-term memory. This will occur for 24 hours or less.
In dissociative amnesia, one is unable to evoke memories related to highly stressful or traumatic experiences. One of the most interesting types of amnesia
2.6. Source amnesia
In this type of amnesia there are certain data or pieces of information that are more or less well remembered , although one is not able to know what their source is, how one has come to know about them.
2.7. Lacunar Amnesia
The inability to remember what happened during a certain period when there was no significant peak in stress . It is called this because it leaves a blank “gap” in the memory.
Post-traumatic or traumatic amnesia is a type of amnesia produced by a blow to the head or a head injury in general . It tends to be transitory and to affect memories of the immediate past. Post-traumatic amnesia should not be confused with forms of amnesia arising from traumatic experiences.
2.9. Dissociative leakage
This type of amnesia, very common in cases of dementia, the person may realize that he is in a place without remembering how he got there . In dissociative flight, moreover, it is very common that aspects of one’s identity are not remembered, causing the person to undertake a more or less long journey to remember who he or she is.
2.10. Wernicke-Korsakoff syndrome
Although not a type of amnesia per se, Wernicke-Korsakoff syndrome is a set of symptoms in which memory impairment plays a very important role. Among its most common symptoms are or a combination of retrograde and antegrade amnesia and confabulation , that is, the involuntary invention of stories that serve to “fill in” the gaps in memory. It is usually caused by alcoholism.