What types of amnesia are there?
The different types of amnesia can be distinguished on the basis of the following characteristics. First, a distinction is made according to the period of memory loss. In the case of anterograde amnesia, memory of future events is lost.
In retrograde amnesia, the patient cannot remember things that happened before the triggering event. Often only memories immediately before the event are lost. In anterograde amnesia, the restrictions of everyday life are therefore severe for the patient, as he or she cannot remember new things.
Furthermore, amnesia can be differentiated according to its extent. In dissociative amnesia there is only incomplete memory loss related to the triggering event. A global amnesia is when the patient does not remember events long ago and is also unable to save new content.
This is the most severe form of memory impairment. It can be temporary. This is called transient global amnesia.
Furthermore, amnesia can be classified according to its cause. Besides organic disorders such as strokes, cerebral hemorrhages, craniocerebral trauma, amnesia can also be psychogenic, e.g. caused by a traumatic experience. In anterograde amnesia, the patient suffers from a memory disorder in which the ability to remember new content is massively restricted.
Memories that lie after the beginning of the triggering event cannot be stored and are lost after a short time. Anterograde means forward facing; here in relation to the temporal dimension. An anterograde amnesia is more frequent than the retrograde form and results in severe everyday restrictions for the person affected.
The causes of anterograde amnesia are numerous: concussion, epileptic seizures, dementia, strokes, brain tumors or poisoning with neurotoxic substances. The type and extent of amnesia can vary greatly depending on the trigger. This also applies to corresponding accompanying symptoms.
For the treatment of anterograde amnesia it is crucial to know the cause of the amnesia. The primary goal of treatment should therefore be to treat the underlying disease. Memory training can be used to try to activate other areas of the brain in order to better compensate for the loss of function.
However, if there has been an extensive death of nerve cells, the amnesia is often permanent. There is then no cure. In retrograde amnesia, there is a loss of memory in relation to a past event.
The affected person has no memory of things that happened before the triggering event. However, the memory gap is usually relatively small, i.e. it is only the short period immediately before the triggering event. Events further back are often well remembered.
There is also no correlation between the extent of brain damage and the duration of memory loss. Several factors are known to trigger retrograde amnesia. This is often the case after a craniocerebral trauma.
The affected person does not remember the course of the accident. Psychogenic triggers are also possible. After a traumatic life event, memory loss occurs.
The experience is not remembered. Retrograde amnesia has also occurred during neurosurgical procedures. This can also be the case after electroconvulsive therapy.
Retrograde amnesia is usually a short-term condition, the long-term memory with regard to future memory is usually not affected. Transient global amnesia is a temporary memory disorder. In the course of which the affected patient can no longer access past memories.
In addition, the ability to remember new content is also massively restricted. Consciousness, however, is preserved. Routine tasks can still be carried out by the affected person without major restrictions.
However, they usually appear disoriented and worried to outsiders. The same questions are often repeated by the patient. This is caused by temporary circulatory disorders in the area of the basiliary artery, an artery that supplies large parts of the brain with oxygen.
The loss of memory is only temporary, lasting on average between 6 and 8 hours. After 24 hours the symptoms should have completely receded, otherwise one can no longer speak of transient amnesia. In dissociative amnesia there are selective memory gaps in relation to autobiographical memories.
These memory gaps can last from several minutes to decades. To be able to make a diagnosis of dissociative amnesia, various organic causes of amnesia must be excluded. Imaging of the brain is essential in order not to overlook any organic brain disorders.
Intoxications can also lead to amnesia and should be excluded. In dissociative amnesia there is a close connection between the memory gap and stressful or traumatic experiences. Therefore, the disorder is also limited to autobiographical memory.
Acquired abilities are remembered. Experts understand dissociative amnesia as a kind of protective function of the psyche in order to avoid having to repeatedly deal with stressful events. Psychotherapy is therefore useful for those affected. Here they learn under psychotherapeutic guidance to work through the stressful experiences in their biography.