Amnesia-colloquially called memory loss-(from Greek a “without,” “not,” and μνήμη mnémē (mnesis) “memory,” “recollection”; synonyms: Memory disorder) refers to a form of memory impairment that is manifested by an impairment of memory in time or content.
Memory is divided into sensory memory (iconic memory; ultra-short-term memory), short-term memory (period: 30-60 min), and long-term memory. Depending on the cause of the memory disorder, the different forms of amnesia occur.
According to the ICD-10, the following forms of amnesia are distinguished:
- Anterograde (forward acting) amnesia (ICD-10-GM R41.1) – memory loss for a certain time after a damaging event.
- Retrograde (retrospective) amnesia (ICD-10-GM R41.2) – memory loss for the period before the harmful event occurred
- Other amnesia (ICD-10-GM R41.3).
Other forms of amnesia include:
- Hypomnesia – reduced memory capacity.
- Infantile amnesia – memory loss in adults who cannot remember events of their own early childhood before a certain age (2-3 years)
- Paramnesia – memory falsifications, mock memories.
- Transient global amnesia (TGA; anamnestic episode) – transient anterograde (new information can be retained for only 30-180 seconds) and retrograde (access to old memory acquired before TGA is impaired) amnesia, along with disorientation or confusion
- Duration: 24 hours max, 6 to 8 hours on average.
- Occurs clustered in the morning
- Etiology (cause) so far not clarified
Amnesia can be a symptom of many diseases (see under “Differential diagnoses”).
Sex ratio: males and females are equally affected by transient global amnesia.
Peak incidence: transient global amnesia occurs predominantly between the ages of 50 and 70 years.
The incidence (frequency of new cases) of transient global amnesia ranges from 3 to 8 cases per 100,000 population per year.
Course and prognosis: The course and prognosis depend on the triggering cause. However, this is not always identifiable or not treatable or only treatable to a limited extent. In these cases, the focus is on training short-term memory and reactivating long-term memory.
After a transient global amnesia (TGA), the affected persons feel limited for several days after the incident. In the long-term course, the symptoms regress completely. There is no increased risk of apoplexy (stroke) or epilepsy; likewise, there is no increased mortality (number of deaths in a given period, relative to the number of the population in question).Because the symptoms of TGA resolve spontaneously, there is no need for specific therapy.
Note: During transient global amnesia, complex motor tasks such as driving can be performed without difficulty.
Transient global amnesia frequently recurs. The recurrence rate is 6-10% per year.
