Memory loss can have different causes and manifestations.
Amnesia consists of the inability to remember past events , or to consolidate new events in memory. Depending on its characteristics, causes and manifestations, we find different types of amnesia.
In this article we will learn about some of the types of amnesia, focusing on two criteria: according to its chronology and according to its causes. We will see how some amnesias can vary greatly from others, and which memories are usually affected in certain pathologies or disorders.
What is amnesia?
Amnesia involves partial or total loss of memory. This encompasses facts, events, information and experiences. It can appear for many reasons, and in addition, it can also vary a lot in terms of manifestations, period of time it covers, characteristics, etc.
It can appear in isolation (as a result of a traumatic event, for example) or as part of another mental disorder (due to Wernicke-Korsakoff Syndrome, for example).
types of amnesia
There are many types of amnesia, depending on the type of forgetfulness that occurs . In addition, the different types of amnesia can be classified according to various parameters.
1. According to the period or chronology
Based on the period covered by the amnesia, amnesia can be divided into two types: anterograde amnesia and retrograde amnesia . That is, in this sense they are classified according to their chronology in time in relation to the appearance of the disorder and the period that covers and/or includes the memory impairment:
1.1. anterograde amnesia
Anterograde amnesia is the inability to record new information . That is, its starting point is the present, therefore it is oriented to the present and the future. It prevents new information from being fixed or consolidated in memory.
1.2. retrograde amnesia
For its part, retrograde amnesia has more to do with the past, and involves the inability to remember events that have already happened . It can span days, months, or even years back in the patient’s life. That is, it covers periods prior to the onset of the amnesia itself.
2. According to the causes
According to the cause that has caused the amnesia, we find the following types of amnesia.
2.1. transient global amnesia
Here the person can remember the fundamental aspects of his identity, as well as things about his immediate past . However, even if he can remember aspects of the past, retrograde memory will be affected. In addition, the person will have difficulties consolidating new information (anterograde amnesia).
Thus, in transient global amnesia (TGA) the immediate memory is preserved, as is the operative memory or working memory (WM); on the other hand, recent memory, like anterograde and retrograde memory, is altered.
AGT lasts a maximum of 24 hours, and its cause is unknown.
2.2. dissociative amnesia
Dissociative amnesia is a specific type of amnesia, which implies not being able to remember relevant personal information, and even forgetting one’s own identity . It is a type of dissociative disorder described as such in the DSM-5 (Diagnostic Manual of Mental Disorders), caused by traumatic or stressful experiences.
Thus, in this type of amnesia, retrograde memory and recent memory are altered (the latter has exceptions, and depends on the content of the material). However, the anterograde memory is preserved, as well as the operational or working memory. In addition, the person with dissociative amnesia maintains semantic memory, procedural memory, and implicit episodic memory.
23. post-traumatic amnesia
Continuing with the types of amnesia according to its cause, we find post-traumatic amnesia or traumatic amnesia. This is caused by a major trauma to the head , that is, a traumatic brain injury (TBI). It is usually a transient amnesia.
The person cannot remember what happened moments before the accident (or even hours or days before). It differs from dissociative amnesia in that dissociative amnesia arises as a consequence of the traumatic experience (on an emotional level) and has a more psychological character; this, on the other hand, is produced by the blow itself.
Thus, to have a general scheme of this type of amnesia, we will say that three types of memories are altered in it: recent, anterograde and retrograde. Instead, immediate memory and working memory (working memory) are preserved; the latter, however, is recovered once consciousness is restored.
2.4. Wernicke-Korsakoff syndrome
This syndrome, caused by chronic and excessive consumption of alcohol and by a deficit in vitamin B1 , causes a frequent type of amnesia. In fact, within the types of amnesia, this syndrome is the most frequent cause of amnesia of organic origin.
It is an anterograde amnesia with minor involvement of retrograde memory (that is, it is an anterograde and retrograde amnesia). Other symptoms such as confabulation also appear.
2.5. amnesia in delirium
As we have seen, amnesia can be caused by organic disorders (such as Wernicke-Korsakoff Syndrome). A delirium may also appear ; A delirium is an organic disorder that produces confusion and a significant alteration in attention and consciousness.
Thus, amnesia in delirium involves alterations in all types of memory: immediate, recent, anterograde, retrograde, and operational or working.
- Related article: “Delirium tremens: what it is, symptoms, causes and treatment”
2.6. Alzheimer’s Amnesia
The amnesia that arises in the context of dementia due to Alzheimer’s disease implies an affectation in recent memory and anterograde memory . Retrograde memory, on the other hand, may or may not be affected, and its degree of involvement is also variable (greater the further the disease progresses).
Immediate memory, on the other hand, is preserved, as well as operational or working memory (at least in the initial moments of Alzheimer’s).
2.7. drug-induced amnesia
This type of amnesia is caused by the consumption of certain psychoactive substances , or by a withdrawal syndrome caused by them. It affects the functioning of memory, making it impossible for the person to remember past events or fix events that have just occurred.
Memory impairment according to disorder
A clue to remember what type of memory is affected in the different pathologies is the following: as a general rule, in organic disorders (such as delirium), the alteration that occurs is in anterograde memory (inability to consolidate new information).
On the other hand, in non-organic pictures (functional pictures, such as dissociative amnesia), the affectation occurs in retrograde memory (inability to remember past events).
bibliographical references
- American Psychiatric Association -APA- (2014). DSM-5. Diagnostic and Statistical Manual of Mental Disorders. Madrid: Pan American.
- Belloch, A.; Sandin, B. and Ramos, F. (2010). Manual of Psychopathology. Volume I and II. Madrid: McGraw-Hill.
- Kolb, B. & Whishaw, I. (2006). human neuropsychology. Madrid: Pan American Medical Editorial.
To the classic question “what do you do?” I always answer “basically I am a psychologist”. In fact, my academic training has revolved around the psychology of development, education and community, a field of study influenced my volunteer activities, as well as my first work experiences in personal services.
