Amnesia

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Amnesia
ICD-10	R41.3
ICD-9	780.9, 780.93
MeSH	D000647

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List of terms related to Amnesia

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [3] ; Aditya Govindavarjhulla, M.B.B.S. [4]

Synonyms and keywords: Memory loss, Forgetfulness, Impaired memory, Amnestic syndrome, Blackout

Natural History, Complications & Prognosis

Diagnosis

History to be obtained | Physical Exam

Treatment

Classification of Amnesia

• In anterograde amnesia, new events contained in the immediate memory are not transferred to the permanent as long-term memory. The sufferer will not be able to remember anything that occurs after the onset of this type of amnesia for more than a brief period following the event.

• Retrograde amnesia is the inability to recall some memory or memories of the past, beyond ordinary forgetfulness.

The terms are used to categorize patterns of symptoms, rather than to indicate a particular cause or etiology. Both categories of amnesia can occur together in the same patient, and commonly result from drug effects or damage to the brain regions most closely associated with episodic/declarative memory: the medial temporal lobes and especially the hippocampus.

An example of mixed retrograde and anterograde amnesia may be a motorcyclist unable to recall driving his motorbike prior to his head injury (retrograde amnesia), nor can he recall the hospital ward where he is told he had conversations with family over the next two days (anterograde amnesia).

• Post-traumatic amnesia is generally due to a head injury (e.g. a fall, a knock on the head). Traumatic amnesia is often transient, but may be permanent of either anterograde, retrograde, or mixed type. The extent of the period covered by the amnesia is related to the degree of injury and may give an indication of the prognosis for recovery of other functions. Mild trauma, such as a car accident that results in no more than mild whiplash, might cause the occupant of a car to have no memory of the moments just before the accident due to a brief interruption in the short/long-term memory transfer mechanism. The sufferer may also lose knowledge of who people are, they may remember events, but will not remember faces of them.

• Dissociative Amnesia results from a psychological cause as opposed to direct damage to the brain caused by head injury, physical trauma or disease, which is known as organic amnesia. Dissociative Amnesia can include:

• Repressed memory refers to the inability to recall information, usually about stressful or traumatic events in persons' lives, such as a violent attack or rape. The memory is stored in long term memory, but access to it is impaired because of psychological defense mechanisms. Persons retain the capacity to learn new information and there may be some later partial or complete recovery of memory. This contrasts with e.g. anterograde amnesia caused by amnestics such as benzodiazepines or alcohol, where an experience was prevented from being transferred from temporary to permanent memory storage: it will never be recovered, because it was never stored in the first place. Formerly known as "Psychogenic Amnesia"

• Dissociative Fugue (formerly Psychogenic Fugue) is also known as fugue state. It is caused by psychological trauma and is usually temporary, unresolved and therefore may return. The Merck Manual defines it as "one or more episodes of amnesia in which the inability to recall some or all of one's past and either the loss of one's identity or the formation of a new identity occur with sudden, unexpected, purposeful travel away from home" [5]. While popular in fiction, it is extremely rare.

• Posthypnotic amnesia is where events during hypnosis are forgotten, or where past memories are unable to be recalled.

• Lacunar amnesia is the loss of memory about one specific event.

• Childhood amnesia (also known as infantile amnesia) is the common inability to remember events from one's own childhood. Whilst Sigmund Freud attributed this to sexual repression, others have theorised that this may be due to language development or immature parts of the brain.

• Transient global amnesia is a well-described medical and clinical phenomenon. This form of amnesia is distinct in that abnormalities in the hippocampus can sometimes be visualized using a special form of magnetic resonance imaging of the brain known as diffusion-weighted imaging (DWI). Symptoms typically last for less than a day and there is often no clear precipitating factor nor any other neurological deficits. The cause of this syndrome is not clear, hypotheses include transient reduced blood flow, possible seizure or an atypical type of migraine. Patients are typically amnestic of events more than a few minutes in the past, though immediate recall is usually preserved.

• Source amnesia is a memory disorder in which someone can recall certain information, but they do not know where or how they obtained the information.

• Memory distrust syndrome is a term invented by the psychologist Gisli Gudjonsson to describe a situation where someone is unable to trust their own memory.

• Blackout phenomenon can be caused by excessive short-term alcohol consumption, with the amnesia being of the anterograde type.

• Korsakoff's syndrome can result from long-term alcoholism or malnutrition. It is caused by brain damage due to a Vitamin B1 deficiency and will be progressive if alcohol intake and nutrition pattern are not modified. Other neurological problems are likely to be present in combination with this type of Amnesia. Korsakoff's syndrome is also known to be connected with confabulation.

Treatment

Memory loss can't be treated unless it is caused by a reversible condition. The treatment is greatly dependent on the primary cause of the condition. When memory loss is a symptom of a more severe disease, it may be reversed as soon as the underlying condition is identified and cured. Memory loss due to aging cannot be cured, but the symptoms may be improved by following the prevention measures.

Family support plays an important role in treating memory loss. Family members are usually encouraged to take special orientation classes on how to cope with their sick relatives and how to help them improve their condition.

Prevention

The most common preventable cause of memory loss is brain trauma, especially trauma resulting from head injury. Preventative measures such as wearing a seat belt while driving or a helmet while biking, can reduce the risk of head injury while participating in dangerous activities.

Eating nutritious foods and reducing stress may help prevent memory loss. In addition, it may be helpful to avoid risk factors such as alcohol abuse and exposure to toxic chemicals. As high blood pressure increases the risk for stroke, and therefore memory loss, blood pressure should be kept under control. Lifestyle adjustments such as smoking cessation and exercise can also further reduce the risk for stroke and brain trauma.

Sleep deprivation and stress are also thought to impact the proper functioning of the brain cells, so it is important to get enough rest and avoid stressful activities.

Socializing is also believed to be beneficial for individuals who may develop memory loss.

Patients whose memory loss is bothersome to the extent that it becomes an issue are encouraged to establish a routine and follow it. Making lists and associations, keeping a detailed calendar as well as always putting important objects in the same place might also help them in remembering more easily and faster. It has been brought to attentionTemplate:Whose? that people who develop mild symptoms of memory loss are more likely to prevent the worsening of the condition if they train their mind by playing strategy games, puzzle, word games or number puzzles and reading. Basically, stimulating the brain can help patients slow down the processes that cause memory loss.

Memory loss among seniors is not inevitable, but is a normal occurrence for many as the brain slows down. This is not the same thing as dementia. Mental functions to do normal activities you have always done, life experience, common sense, and the ability to form reasonable judgments and arguments are not affected.

Exercise, especially aerobic exercise, helps combat or restore memory loss. Studies indicate that exercise lessens stress, increases blood flow, and stabilizes and deepens sleep patterns. Even walking a few times a week helps fight memory loss.

See also

• Emotion and memory
• False memory
• HM (patient)