ANTEROGRADE AMNESIA: SYMPTOMS, CAUSES AND BRAIN AREAS - NEUROPSYCHOLOGY - 2024

The anterograde amnesia is a type of amnesia that causes memory loss about new developments. That is, the person suffering from this condition is unable to learn new information. It is also often called short-term memory loss, although recent research indicates that this alteration also affects long-term memory.

The processes of attention and immediate memory are preserved in anterograde amnesia, however, the information is not stored correctly in the long term, so it is eventually forgotten.

Anterograde amnesia is a disorder that can be caused by several causes. In fact, it is a symptom that can be seen in different pathologies. People who suffer from this disorder are unable to remember new aspects and have many learning difficulties.

Characteristics of anterograde amnesia

Anterograde amnesia is a selective memory deficit that occurs as a consequence of brain damage in which the individual has significant difficulties in storing new information.

In contrast, anterograde amnesia does not affect the recall of past information. All the information stored prior to the appearance of the alteration are fully preserved and the person is able to remember it without problem.

In general, this alteration tends to affect the learning of new information completely. However, some people with this type of amnesia are able to learn new skills and habits.

Likewise, some cases of anterograde amnesia have been reported in which affected individuals have been able to learn new games or write in reverse.

It is shown that anterograde amnesia mainly affects the storage of facts and events, while the learning of skills seems to be more preserved.

Brain areas involved

Determining which brain regions are involved in the development of anterograde amnesia is one of the major challenges in science today.

It is argued that the brain damage that causes anterograde amnesia is located in the hippocampus and areas of the medial temporal lobe.

Hippocampus

These brain regions act as a passageway where events are temporarily stored until they are stored more permanently in the frontal lobe.

The hippocampus is interpreted as a short-term memory store. If this region does not allow the information to be stored correctly, it will be impossible for it to pass to the frontal lobe, so memories cannot be established.

However, despite the fact that the hippocampus appears to be the most important region of anterograde amnesia, recent studies have postulated the involvement of other brain structures.

Specifically, it is theorized that damage to the basal forebrain could also cause this condition. These regions are responsible for producing acetylcholine, a main memory substance, since it initiates and modulates the memorization processes.

The most common form of anterior basal brain damage is aneurysms, a condition that has been positively associated with anterograde amnesia.

Finally, the relationship between memory disorders and Korsakoff syndrome has suggested that a third region could also be involved in the development of anterograde amnesia.

This last structure is the diencephalon, a region that is highly damaged with Korsakoff syndrome. The high association between anterograde amnesia and korsakoff syndrome means that the participation of the diencephalon in mnesic processes is currently being studied.

Causes

Anterograde amnesia is a disorder that can appear in a wide variety of diseases.

In some cases, the amnesia experienced is temporary and the person can recover their memory correctly. However, in other diseases memory loss can be progressive and chronic.

The main pathologies that can cause anterograde amnesia are:

Use of benzodiazepines

Benzodiazepines are anxiolytic drugs whose side effects include memory failures. The main medications that can cause anterograde amnesia are lorezepam,, triazolam, clonazepm, and diazepam.

In these cases, it is convenient to withdraw the medication. Normally, memory functions usually recover after drug withdrawal, and anterograde amnesia disappears.

Head trauma

Head injury is one of the main causes of anterograde amnesia. The damage caused by the impact in the brain regions that modulate memory processes can cause chronic anterograde amnesia, although memory capacity can sometimes be restored.

Encephalopathy

Encephalopathy is a disease that causes a loss of brain function when the liver is unable to remove toxins from the blood. The alteration can appear suddenly or progressively, and usually causes anterograde amnesia.

Alcohol poisoning

Anterograde amnesia can also be caused by alcohol intoxication. This phenomenon is popularly known as "blackout" and causes memory loss for a certain period of time.

Dementia

Dementia syndromes are characterized by the generation of neurodegeneration of the brain. One of its first symptoms is usually the progressive and chronic loss of learning capacity (anterograde amnesia) although later it causes many more cognitive deficits.

Delirium

Delirium is a disorder of consciousness that can be caused by different factors. Due to the alteration suffered by attention and consciousness, memory is highly damaged in this pathology. Normally, anterograde amnesia disappears once the disease is over.

Korsakof syndrome

Korsakof syndrome is a very common pathology caused by thiamine deficiency in subjects with chronic alcoholism. In these cases, recent memory is more altered than remote memory.

Benign forgetfulness of age

Finally, the aging of the brain causes it to deteriorate and lose functionality. In these cases, there is no mention of pathology, but there may also be difficulties in learning and remembering new information.

References

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