MEMORY DISORDERS: TYPES AND THEIR CHARACTERISTICS - ECONOMÍA - 2024

The memory disturbances can be classified into changes fixation and evocation (clinically). From a chronological point of view, memory impairment can be anterograde and retrograde. Finally, there are others whose causes are organic. In this article we detail them all in detail.

Memory constitutes one of the most important psychic activities of human beings. In fact, all people need this mental ability to be able to function properly in any of our areas or activities that we carry out.

Popularly, memory is related to the ability to recall previous aspects or experiences. However, despite the fact that this statement can be interpreted as true, memory is an activity that does much more than provide memory, since it also allows information to be captured and stored in brain structures.

As memory performs various activities, the alterations that can be suffered in this psychic activity can also take different forms.

The three basic functions of memory

In order to understand why people can suffer from different memory disorders, we must first understand what are the main activities carried out by this psychic ability.

Memory works as a device that performs three main functions. These are fixation, preservation, and evocation.

Fixation

It refers to the mental activity carried out by the uptake of material, its perceptual elaboration and the fixation on the corresponding brain structures.

In this way, fixation constitutes the main element that determines learning since it allows to retain and store the information captured by the senses.

Conservation

It constitutes the next activity that memory performs and consists of storing and above all preserving the information previously captured.

Without this ability, the information would enter the brain structures but would not be maintained, so the memory would disappear easily.

Evocation

This last main function of memory allows to update and reproduce in consciousness in the form of mnesic images the memories that are already stored in memory.

Without the activity of evocation, the information would be stored in the mind but we would not be able to retrieve it, so it would be useless to have memory.

Memory alterations can be different depending on the memory activity that is affected. In addition, these types of alterations can be classified according to different categories. Therefore, not only the altered memory activity or the suffered memory failure are relevant.

Etiological classification, chronological classification, and modes of memory impairment are also important concepts.

Next, we will review and explain the different types of memory disorders classified according to the memory mechanism affected, according to the chronology and according to the cause

Memory disorders according to the memory mechanism affected (clinical point of view)

Clinically, the relevance of the type of memory alteration lies mainly in the memory mechanism that is affected. In this way, we can classify the types of alterations based on fixation and evocation.

The alterations that can be witnessed based on these criteria are the following.

-Alterations of fixation memory

This type of alteration is characterized by presenting failures in the fixing process. This activity is essential to be able to remember since if it does not work, the memory cannot be formed and the memory is empty of content.

Alterations in fixation memory are revealed when an event or experience passes through us devoid of affective content, that is, indifferently.

This failure is closely linked to attention, since we cannot capture the stimuli firmly enough to form a consistent memory that can be fixed on brain structures.

The alteration can appear in different ways and with different intensities, so it can make a pathological condition or a relatively normal or benign condition.

When it comes to a pathological alteration of the fixation memory, the person may feel interest in an experience or a specific stimulus but not be able to grasp and fix it, so the aspects hardly leave a trace and later it is not possible to remember it.

In other words, the pathological condition in this type of memory produces an inability to learn and retain new information. The three main forms that this condition can take are:

Total or massive

It is characterized by suffering from a total inability to establish an experience. A very significant case is the one that occurs in Korsakoff syndrome, an alteration produced by chronic alcoholism and some head trauma. In these cases, the patient is unable to fix in his mind the totality of the events that occur around him.

Life slides through the patient without leaving a trace and the person becomes mentally empty and reduced to the memories of past events, which, since they are already stored, are remembered normally.

In these cases, it is usually common to witness what is known as fabulations, that is, sometimes detailed stories about lived events but that do not belong to memories but are products of fantasy and imagination processes.

Lacunar

This condition does not properly constitute an alteration of fixation memory but is produced as a consequence of a profound alteration of consciousness.

In these cases, the loss of the memories covers a certain period of time, usually during the moments in which a confusional syndrome, an epilepsy or a toxic psychosis is suffered.

Partial

Finally, in this last type of fixation memory alteration, the ability to retain new information is inhibited or diminished. The person may have a certain ability to fix information in their brain structures but with greater difficulties and less effectively than other people.

This condition can occur either from organic causes such as brain injuries or from affective disorders.

-Evocation memory disturbances

Evocation memory refers to the ability that people have to retrieve information that has been previously stored in brain structures. These types of alterations can be divided into quantitative and qualitative.

-Quantitative alterations in evocation memory

This condition refers to the number of failures that are witnessed in the evocation memory. That is, it defines the amount of information stored in the brain that the person is capable of evoking. We can find 3 different alterations:

Hyperamnesia

It constitutes an increase in the capacity for evocation. It can be observed in cases of great calculators and of certain memory prodigies. This alteration can also be seen as a symptom of manic arousal.

Hypomnesia

It constitutes a decrease in the ability to evoke, which makes it more difficult for the person to recover their memories. It is usually a typical symptom of depressive pictures.

Retrograde amnesia

It involves an inability to evoke memories. Failures can refer to certain experiences (systemic amnesias) specific times (localized amnesias) or to all previously stored memories (general amnesias).

-Qualitative alterations of the evocation memory.

Unlike the previous alterations, this type of affections are classified according to the characteristics of the memory failure that is present. They constitute strange disorders with particular properties. Two main types can be distinguished.

Fables

It constitutes the story made by a patient about invented memories that have never happened. In some cases they serve as a "filler" to cover memory gaps, as occurs in some pathologies such as Korsakoff Syndrome.

Paramnesias

They constitute false acknowledgments. You can suffer from the phenomenon of the "Already seen" where the subject attributes the character of known to a new or unknown fact, and the phenomenon of the "Never seen" where the individual attributes the character of unknown to an element already known.

Alterations in memory according to chronology

According to the chronological characteristics of the aspects that cannot be remembered, memory alterations can be classified into two different types of conditions:

-Antrograde amnesia

It refers to the inability to learn new information after the onset of the disorder that led to the amnesia. The person is able to remember previously stored aspects but forgets at the same time that new information is presented and captured.

As we can see, in these cases the fixation capacity is damaged, it occurs after head injuries or organic alterations and they usually constitute reversible conditions.

-Retrograde amnesia

This type of alteration refers to the opposite of what was stated in the previous case. The individual with this retrograde amnesia is unable to remember the information learned prior to the onset of the disorder.

Usually the memories that are closest in time are usually forgotten first and later the more remote memories are forgotten.

This type of amnesia can be witnessed in Alzheimer's disease where the person can forget even their own identity or that of their closest relatives.

Memory alterations according to the cause

Memory disorders can also adopt different characteristics depending on their etiology, that is, depending on the factors that cause the appearance of memory failure.

In general, we can differentiate two main types: alterations caused by organic causes and those caused by affective or psychological factors.

-Organic causes

These memory alterations are produced by a physical pathology that damages brain function and memory mechanisms. There are 6 main types of these types of conditions:

Korsakoff syndrome

It is an amnesic syndrome caused by a deficiency of thiamine in the brain. The most frequent situation lies in the nutritional deficit produced by chronic alcoholism, although it can also originate after other diseases such as gastric carcinoma or hypermesis gravidarum.

Before the appearance of this syndrome, recent memory is highly affected, while remote memory remains more conserved. Likewise, memory loss can be accompanied by other symptoms such as apathy, passivity, false recognition or fabrications.

Alcoholic blakcouts

After a high intake of alcohol, the individual may wake up without the ability to remember what happened during drunkenness. This memory alteration affects only the information witnessed during moments of intoxication.

Transient global amnesia

It is a sudden onset disorder that usually lasts between 6 and 24 hours in which the person is unable to remember absolutely anything that happened during the episode.

Dementia

It is the main cause of memory impairment, it is usually caused by neurodegenerative diseases such as Alzheimer's or Parkinson's, and is accompanied by other cognitive failures such as language disorders, impaired motor skills or deficits in the ability to recognize objects.

The condition is characterized by being chronic and progressive, so memory failures start out mild but gradually increase irreversibly.

Delirium

It is a memory disorder secondary to a severe alteration of consciousness and a decrease in the ability to maintain attention.

It is usually caused by organic diseases and usually lasts a few hours but later the ability to remember gradually recovers.

Benign forgetfulness of age

With age, memory failures may appear and learning capacity may be slightly diminished.

This condition is part of the normal aging of the individual and is not considered pathological.

-Affectionate causes

Suffering from certain psychological alterations can cause deficits and disorders in the functioning of memory. The most typical cases are selective amnesia produced by post-traumatic stress where the person is unable to remember some of the events that happened, and anxiety amnesia in which fixation memory can be altered.

Another very common case is dissociative or psychogenic amnesia in which the individual is unable to remember relevant personal information and which are accompanied by affective states such as anxiety, high stress and, in some cases, depression.

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