Amnesia. Types of amnesia

Amnesia is a condition in which a person is unable to recall parts of their memory. In some cases, amnesia occurs because of physical damage to the brain. In other cases, emotional distress can lead to the psychological disorder dissociative amnesia.
Amnesia is different from dementia. Dementia includes memory loss, but it also involves other important cognitive problems that may affect the patient’s ability to carry out daily activities.

Types of Amnesia
Anterograde amnesia
happens as a result of brain trauma that involves the hippocampus, fornix, or mammillary bodies.
Here the person is unable to recollect events, that occur after the onset of the amnesia, for more than a few minutes. Recent events are not transferred to long-term memory.
2) Retrograde amnesia
In this form of amnesia the affected individual will be unable to recollect events that occurred before the amnesia set in. Memory is poorest regarding events that occurred just before amnesia set in. Early memories are comparatively safe with memory decline building up to the event.

3) Dissociative amnesia
This is a condition in which the patient is unable to remember vital personal information in a way that has nothing to do with normal forgetfulness. It is commonly seen in individuals who have witnessed a violent crime or a grave accident and does not occur due to a medical illness.
Patients with dissociative amnesia do not experience an identity crisis but they tend to pass through a trance-like state and may develop depersonalization as an effort to block out a stressful experience.
4) Traumatic amnesia
Memory loss results from a hard blow to the head. The person may experience a brief loss of consciousness or a coma. The amnesia is usually temporary, but how long it lasts normally depends on how severe the injury is. Amnesia can be an important indicator of concussion.

5) Transient Global Amnesia (TGA)
A temporary loss of all memory and, in severe cases, difficulty forming new memories. This is very rare and more likely in older adults with vascular (blood vessel) disease.
6) Wernike-Korsakoff's psychosis
This amnesia is a progressive disorder caused by extended alcohol abuse. It is usually accompanied by neurological dysfunctions such as loss of co-ordination during movement or a feeling of numbness in the fingers and toes. It can also be caused by malnutrition, specifically a thiamin (vitamin B1) deficiency.
7) Infantile amnesia (although not a disease)
The inability to recall events from early childhood is known as infantile amnesia. It is assumed that this happens due to immaturity in certain areas of the brain in the very early stages.

Causes
Any disease or injury that affects the brain can interfere with memory. Memory function engages many different parts of the brain simultaneously.
Medical amnesia
Amnesia resulting from brain injury or damage.
Possible causes are:
Stroke
Encephalitis
Oxygen deprivation
Some medications
Subarachnoid hemorrhage, or bleeding in the area between the skull and the brain
A brain tumor that affects a part of the brain involved in memory
Psychological amnesia
Also known as dissociative amnesia, this is caused by an emotional shock, such as:
A violent crime
Sexual or other abuse
Military combat
A natural disaster
A terrorist act
Psychological amnesia are more likely to disrupt personal, historical memories rather than interfere with laying down new memories.

Diagnosis
There is no specific diagnosis procedure for psychological amnesia. Generally, the patient’s statement of memory loss is enough to qualify for a diagnosis of amnesia. But to be sure that is the psychological amnesia rather than physical, a doctor may perform brain imaging scans and blood work.
Diagnosing dissociative amnesia has been somewhat controversial in the medical community because many homicidal criminals have used it as a courtroom defense for their actions.

Treatment
Some types of memory loss are best handled by medical teams. People who have head injuries, brain tumors and other physical ailments may find that they’re able to make new memories and process old ones when their underlying health concerns are addressed in a comprehensive manner.
Some patients can be helped by psychotherapy. Family support is also plays crucial role in this cases. Photographs, smells, and music may help too.

Questions
What can cause amnesia?
Do all types of amnesia manifest the same way?
Are all the types of amnesia considered as disease?
Is any memory loss considered as amnesia?
What is the difference between medical and psychological amnesia?
Why do people lie about having amnesia?