Types of amnesia and their respective features

Amnesia is defined as a condition in which a person suffers from the inability to retrieve memories or retain new information temporarily or for a long time, and there are many types of amnesia with different characteristics of each, and a person may suffer from more than one type at the same time.

This article discusses the most prominent types of amnesia and what distinguishes each type from the other.

Memory is a set of processes used by the brain to record, store and retrieve information when needed, and memory is divided into 3 types :

• Sensory memory : it is the type of memory that receives sensory input of all kinds, in which the information lasts for less than a second, and is usually forgotten, or transferred to the next stage.

• Short-term memory : this memory retains active information, and thoughts often last 10 to 30 seconds.

• Long-term memory : this memory stores information for a minute or more.

Types of amnesia

Types of memory loss include :

Regressive amnesia

In this type, a person loses the ability to recall memories prior to the event or trauma that led to memory loss, and nearby events are usually affected, but the patient is able to remember old information, and retain new information.

Progressive amnesia

This type is more common than regressive amnesia, in which a person suffers from the inability to form new memories after the trauma causing memory loss, while he can recover old memories, for example, the patient may not be able to remember the events of his day, but he remembers attending a party 30 years ago.

Progressive amnesia can be temporary in some cases, such as excessive drinking, while it may become permanent in the case of damage to the hippocampus, an area of the brain that has a role in the formation of memories.

Transient mass amnesia

Transient global amnesia is a type of sudden and temporary amnesia, in which total memory loss occurs suddenly, so the person cannot form new memories or recover old ones, and despite his ability to think and know his identity and family members, he is unaware of time and place. Memory loss is usually for a short period that lasts from one to ten hours and then gradually returns spontaneously.

Transient global amnesia is not known, but it may be caused by several factors, such as a psychiatric disorder, epilepsy, or problems with blood flow, and this type of memory loss often occurs in older or middle-aged people.

Traumatic amnesia

It is memory loss that results from severe head trauma, such as memory loss due to a traffic accident, where a person suffers from loss of consciousness or a short coma, and this may indicate a concussion. Memory loss is usually temporary in this case and it depends on the severity of the injury.

Infantile amnesia

Types of amnesia also include infantile amnesia, which is the inability of a person to remember the events of the first years of life, due to incomplete brain development, however, some events, such as being abused or neglected in childhood, leave a psychological impact on the person.

Dissociative or dissociative amnesia

Dissociative amnesia is a type of traumatic amnesia in which partial memory loss occurs in which a person forgets periods of their life and, in some cases, their past or identity. Memory often returns within minutes, hours or days, but the traumatic event may not return completely.

It is worth noting that in rare cases, a person does not regain his memories and identity, and begins his life again with a new identity, which is known as separatist fugue.

Medication-induced memory loss

Some types of medications can cause temporary memory loss, such as :

• Benzodiazepines, such as alprazolam and chlordiazepoxide.

• Sedatives, such as zolpidem (English: Zolpidem).

• Flunitrazepam and quitamine.

It should be noted that general anesthesia before surgery may lead to memory loss, such as pentobarbital and phenobarbital.