The 12 types of Amnesia (and their characteristics)

There is no doubt that human beings are quite a feat of biological evolution. And it is that the list of physiological attributes that, for better and for worse, has made us become the dominant species on planet Earth is practically infinite. But among all of them, there is one that shines with its own light. One that constitutes the fundamental element of human nature.

We are talking, as it cannot be otherwise, of memory. The ability to store information in the corners of our brain in the form of memories and retrieve it both voluntarily and involuntarily determines who we are and how we relate to the people and environment around us. Without memory, we are but a sack of organic matter.

Therefore, all those situations that may threaten the integrity of our memory generate us, understandably, fear and fear. And this is where the protagonist of today's article comes into play: amnesia. A disorder that involves the partial or total loss of memory, affecting our ability to remember events or store new information.

Thus, in today's article and, as always, from the hand of the most prestigious scientific publications, We will review the clinical bases of amnesia, also seeing how it is classified into various types according to both the chronology of memory loss and the causes behind it. Let's see what kinds of amnesia exist.

What is amnesia?

Amnesia is a disorder that involves partial or total loss of memory. It is a clinical condition that, for different reasons, is based on a deficit in the brain mechanisms associated with memory, which is why the person has more or less serious problems when it comes to retrieving, preserving or entering information.

In this sense, amnesia causes a partial or complete inability to generate new memories, retrieve information that was familiar to us, or retrieve memories. In the vast majority of cases, amnesia affects short-term memory, so the more distant memories rooted in long-term memory are generally not lost. Therefore, the problems come when it comes to retrieving recent memories and storing new information in the brain.

In any case, despite the fact that this memory impairment can be serious (the severity and scope varies greatly between people and depending on the cause behind it), there is no damage to other cognitive abilities. And it is that unlike other conditions that damage memory such as memory, intelligence, understanding, orientation, social skills, physical abilities, motor functions, attention span or reasoning remain intact.

Therefore, amnesia is a disorder whose neurological impact is limited solely and exclusively to memory, and specifically, generally only to short-term memory. In addition, it is often a transitory disorder that arises after trauma or strong emotional shocks but in which memory recovers.

Other times, however, it is possible that amnesia is a permanent pathological condition, and depending on how deep the affectation is, it can cause serious problems in both personal and professional life. In these cases, treatment through occupational therapy becomes essential. That is why it is so important to know what kinds of amnesia exist.

What kinds of amnesia are there?

Amnesia, as we have seen, is a disorder that affects memory, causing a partial or total loss of memory. Even so, due to its diversity in terms of severity and scope, it has been necessary to classify the various manifestations of amnesia into different types according to both their chronology and the cause behind the disorder. And this is what we are going to analyze next. Let's see what types of amnesia exist.

1. Retrograde amnesia

Depending on the chronology, that is, the period covered, amnesia can be retrograde or anterograde. Let's start with the first one. Retrograde amnesia is one that is based on inability to recall events prior to the onset of the disorder. Its starting point is the past, so the person can remember events that have occurred after, but not those before the onset of amnesia.

2. Anterograde amnesia

Retrograde amnesia is one that is based on inability to incorporate new information into memory. Its starting point is the present, as it affects the way we register new memories. Recent events that must be stored in short-term and later long-term memory vanish before they are recorded. But everything prior to the onset of the disorder can be remembered.

3. Dissociative amnesia

Dissociative amnesia is one in which the person is unable to remember personal events that represented negative or emotionally stressful experiences. Access to a traumatic event is restricted without any illness behind it beyond psychological explanations. It is a rare disorder.

4. Lacunar amnesia

Lacunar amnesia is one that is based on memory "gaps", that is, in the inability to remember some event from the past. It differs from dissociative in the sense that it is not experienced by a stress peak or a traumatic experience. They are simply "blank" holes in memory.

5. Post-traumatic amnesia

Post-traumatic amnesia is one in which memory loss occurs as consequence of head injury. That is, amnesia, which is generally temporary, appears after a strong blow to the head. The person does not remember what happened moments before the trauma, but not because of the emotional or psychological shock (such as dissociative shock), but because of the physical injury itself.

6. Source amnesia

Source amnesia is one in which memory loss is not based on not remembering certain information, but where it was obtained. That is, we have access to the content itself, but we do not know its source. What we have forgotten and we can't remember is when, how and where we learned something.

7. Amnesia in delirium

Amnesia in delirium is one in which memory loss is accompanied by delirium, a state of mental confusion that is accompanied by hallucinations, sleep disturbances, disorganized thinking, disorientation and agitation. In this case, the amnesia is usually related to an organic disorder such as Wernicke-Korsakoff syndrome.

8. Transient global amnesia

Transient global amnesia is one that born from the combination of retrograde and anterograde amnesia. The person can remember fundamental aspects of their identity, but has forgotten many aspects of the past and cannot consolidate new memories. It is a rare condition with an unknown cause that lasts for about 24 hours in patients who develop it, most of them being between 55 and 75 years old.

9. Drug-induced amnesia

Drug-induced amnesia is one in which memory loss occurs as consequence of the consumption of psychoactive substances or due to their withdrawal syndrome. This includes not only recreational drugs, but some medications such as flunitrazepam that can trigger anterograde amnesia.

10. Amnesia due to neurodegeneration

Neurodegenerative amnesia is one in which memory loss It is one more consequence of the impact that a neurodegenerative disease has on our brain. It is one more manifestation within dementia, the set of cognitive, physical, behavioral and social damages triggered by the progressive and irreversible degeneration of brain neurons.

If there are 50 million people with dementia in the world, between 50% and 70% of the cases are due to Alzheimer's, the neurodegenerative disease that is famous for the loss of short, medium and long-term memory that it induces. In amnesia induced by Alzheimer's or any other neurodegenerative disease, memory loss occurs due to slow but continuous damage to brain cells.

11. Infantile amnesia

Infantile amnesia is one that is based on inability to recall childhood events and events, that is, of the first 3-4 years of life. Even so, it is not considered a disorder as such, since it is a normal (not pathological) consequence of the development of the central nervous system, which makes us forget much of what we have experienced in childhood.

12. Medial diencephalic amnesia

Medial diencephalic amnesia is one in which memory loss is experienced as a result of injury to the medial diencephalon, a part of the brain that is located in the medial region of the brain and connects the endocrine and nervous systems. The damage appears to be generally located in the hypothalamus and thalamus.