Amnesic disorders: types, characteristics, symptoms, and causes

There are a wide variety of disorders in which amnesia appears as the main symptom, these being known as amnesic disorders. These disorders could be due to both the persistent action of substances and the physiological effects of a general medical condition.

Amnestic disorders are characterized by markedly impaired memory for recalling remote events; while in these cases they normally remember facts or immediate events. On the other hand, the ability to learn and remember new things is greatly affected (anterograde amnesia), which could lead to time orientation problems.

In this article you will find a summary of what amnestic disorders consist of, what are their diagnostic criteria and also the different types of these pathologies that exist.

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What are amnestic disorders?

When we speak of the word amnesia in psychology, we refer to the partial or even complete loss of memory functions, which means that the person who suffers it will be unable to acquire (retain) and/or evoke (retrieve again) the information

, so it would be impossible for him to remember or retain the information of a specific period of time.

Amnestic disorders, on the other hand, are a series of syndromes characterized primarily by impaired memory strong enough to remember remote events, while the memory to remember immediate events or events is usually preserved. In addition, the ability to learn and remember new things is greatly affected (anterograde amnesia), which could lead to problems with orientation in time.

In amnestic disorders we can also find anterograde amnesia, although of varying degrees of intensity, and may also decrease over time, in which case the underlying disease and/or pathological process have a tendency to remit over time, with a medical and psychotherapeutic approach that has been started in time and is appropriate for this type of cases.

The prognosis of amnestic disorders will depend on the course of the basic lesion, which normally affects the brain region of the hippocampus or to the hypothalamic-diencephalic system. Initially, there may be a complete recovery.

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Classification and diagnostic criteria of amnesic disorders

In the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV-TR), of the American Psychiatric Association (APA), we can find classified to amnestic disorders within the following category: “Delirium, dementia, amnestic disorders and other disorders cognitive”. Next we will see what are the diagnostic criteria of amnesic disorders in the DSM-IV-TR.

People with some of the types of amnestic disorders primarily have impaired ability to learn new information, and also fail to recall past events or previously learned information (Criterion A). The memory alteration could be detrimental enough to cause a notable deterioration in social or work activity., which may represent a significant decrease in the level of activity that they previously had (Criterion B). The memory disturbance does not appear exclusively during the course of dementia or delirium (Criterion C).

It should be noted that the ability to remember new information is always affected, while the difficulty in remembering information that had been learned before the disease can present itself in a more variable way, depending on the severity and/or location of the lesion cerebral.

Besides, the deficit in memory is usually more apparent in those tasks in which spontaneous recall is necessary, this deficit may be evident at the moment in which the examiner provides the person suffering from some of the amnestic disorders with a series of stimuli so that they can evoke them later. These deficits could be predominantly related to visual or verbal stimuli depending on the brain area that is specifically affected.

In some types of amnestic disorders, the affected person may be able to better remember things from the very remote past, which events that have happened more recently (for example, the person remembers when they went on vacation with their family abroad more than a decade ago, being able to express the details of said event, but, instead, he does not remember what he did that same morning).

Should memory impairment appear exclusively during the course of a delirium Diagnosis of amnestic disorders (eg. if it only occurs in the context of a reduction in your ability to direct or sustain attention).

Also, in amnesic disorders the ability to immediately repeat a sequence of information is not impaired (p. g., repeating some digits that you just heard) and, in the event that this capacity is affected, it was necessary to suspect that there was an alteration of the capacity of attention, which could be an indication that he was suffering from a delirium.

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Symptoms of amnesic disorders

There are a series of symptoms that allow us to detect when we would be facing a case of amnesic disorder, as we will see below. In the first place, it is worth mentioning that amnestic disorders are diagnosed in the event that there is other cognitive deficits that are characteristic of dementiato (p. g., agnosia, aphasia, or performance impairment). In addition, people with any of the amnestic disorders may experience, due to their severe memory deficits impaired social or personal skills, requiring daily supervision day.

On the other hand, it is quite common for amnestic disorders to come preceded by a clinical picture of disorientation and confusion, as well as attention span problems that would suggest the possibility that the person were suffering from a delirium, as is the case with amnestic disorders caused by a deficiency of thiamin.

When amnestic disorders begin to develop, it is quite common for there to be confabulations, although they tend to disappear after a while; however, this makes it necessary for the clinician performing the assessment with the patient has to resort to the help of relatives or close friends to gather information important.

In case of profound amnesia, the patient could suffer from temporal-spatial disorientation.; however, autopsychic disorientation is rare, as it is more common in cases of dementia.

On the other hand, patients with amnestic disorders they find it difficult to recognize their memory deficit, so they could explicitly deny the possibility that they were suffering from this deterioration. There could also be some personality changes such as emotional fragility, lack of initiative or apathy, among others.

In addition, patients with amnestic disorders may be only superficially pleasant and friendly, since show very poor or narrow affective expressiveness.

On the other hand, in cases of transient global amnesia, patients may appear dazed and perplexed. Less severe deficits in other cognitive abilities may be seen, but not severe enough to cause clinically significant impairment.

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Types of amnesic disorders

Now that we have seen what amnestic disorders consist of, what are their criteria diagnoses and their symptoms, we are going to see the types of amnestic disorders that we can find in the DSM-IV-TR.

1. Amnestic Disorders Caused by a General Medical Condition

In this case, Criteria A and B would be the same as those explained above for all amnestic disorders in general, in this case being caused by a general medical condition.

Besides, for this diagnosis it would be necessary to demonstrate it through his clinical and vital history, a physical examination and/or through tests carried out in the laboratory, in order to be able to verify that the memory impairment suffered by the patient has been directly caused by a general medical condition (Criterion D).

Medical Conditions That Can Most Commonly Cause Amnestic Disorders are the following:

• Bullet wounds.
• Closed head injury.
• Hypoxia.
• Surgical intervention.
• Herpes simplex encephalitis.
• Posterior cerebellar artery infarction.
• Lesions in the medial area of ​​the temporal lobe and in specific diencephalic structures.

2. Substance-Induced Persisting Amnestic Disorders

Criteria A and B are the same as those explained above for all amnestic disorders in general, in these cases being substance-induced. Criterion C requires that the memory disturbance does not occur exclusively during the course of delirium or dementia, and must persist beyond the usual time of abstinence to substances or the usual time of intoxication to substances.

In addition, it is necessary to carry out an examination of your medical and life history, a physical examination and/or laboratory tests to be able to verify that this alteration in memory is directly related to the effects of substances (Criterion D).

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3. Amnestic disorders not otherwise specified

The diagnosis is made in those cases in which criteria necessary to diagnose any of the above amnestic disorders are not met (p. For example, when we meet a patient who suffers from amnesia, but there is no evidence that demonstrate its specific etiology, such as could have been due to substances or a disease, among others).