Amnesia

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Amnesia
ICD-10	R41.3
ICD-9	780.9, 780.93
MedlinePlus	003257
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

Overview

Amnesia (from Greek Template:Polytonic) is a condition in which memory is disturbed. The causes of amnesia are organic or functional. In simple terms it is the loss of memory. Organic causes include damage to the brain, through trauma or disease, or use of certain (generally sedative) drugs. Functional causes are psychological factors, such as defense mechanisms. Hysterical post-traumatic amnesia is an example of this. Amnesia may also be spontaneous, in the case of transient global amnesia. This global type of amnesia is more common in middle-aged to elderly people, particularly males, and usually lasts less than 24 hours. Memory loss can be partial or total, and it is normal when it comes with aging.

Another effect of amnesia is the inability to imagine the future. A recent study published online in the Proceedings of the National Academy of Sciences shows that amnesiacs with damaged hippocampus cannot imagine the future[5]. This is because when a normal human being imagines the future, they use their past experiences to construct a possible scenario. For example, a person who would try to imagine what would happen at a party that would occur in the near future would use their past experience at parties to help construct the event in the future.

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" [6]. 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.

Pathophysiology

The memory is affected by the damage that may occur in the different parts of the brain such as medial temporal lobe, hippocampus, cortex and frontal lobes. Injuring any of these areas may lead to specific disruptions in the processes of acquiring and restoring memory. For instance, damage to the medial temporal lobe and hippocampus can devastate the ability to acquire new declarative memory whereas damage to the storage areas in cortex can disrupt retrieval of old memories and interfere with acquisition of new memories.

Causes

Common causes

• Side effects of Medication: Many drugs can cause cognitive problems and memory loss as a side effects, common in adults. Common drugs that affect memory and brain function include sleeping pills, antihistamines, blood pressure and arthritis medication, antidepressants, anti-anxiety medications, and painkillers.
• Depression: Depression mimics the signs of memory loss. It is a common problem in older adults—especially if one is less social and active than they used to be or if one has recently experienced a number of major life changes (retirement, a serious medical diagnosis, the loss of a loved one, moving away from home).
• Vitamin B12 Deficiency: Vitamin B12 protects neurons and is vital to healthy brain functioning. A lack of B12 can cause permanent damage to the brain.
• Trauma : This is the most common cause of preventable memory loss.

Causes by Organ System

Cardiovascular	Arteriovenous Malformation, Cerebrovascular accident, Multi infarct dementia, Subarachnoid hemorrhage, Transient ischemic attack
Chemical / poisoning	Aluminium poisoning, Barbiturate abuse, Bromoform, Cannabis, Hobo spider poisoning, Mercury poisoning , Stachybotrys chartarum, Toluene, Neurotoxicity syndromes
Dermatologic	No underlying causes
Drug Side Effect	Anagrelide, Anisotropine Methylbromide, Diazepam, Dicyclomine, Flecainide, Lamotrigine, Levetiracetam, Midazolam , Modafinil, Nefazodone, Oxcarbazepine, Phenelzine, Pramipexole, Ropinirole, Selegiline, Temozolomide, Trazodone, Valium, Zaleplon, Zolpidem|-
Ear Nose Throat	No underlying causes
Endocrine	Hashimoto's Thyroiditis, Hyperthyroidism, Hypothyroidism
Environmental	Anoxia, Frostbite, Heat stroke, Hypoxia
Gastroenterologic	No underlying causes
Genetic	Citrullinemia , Down Syndrome, Graeck-Imerslund disease
Hematologic	No underlying causes
Iatrogenic	Bilateral temporal lobectomy, Carbon monoxide poisoning, Electroconvulsive therapy
Infectious Disease	AIDS Dementia Complex, Cryptococcal Meningitis, Encephalitis , Herpes simplex encephalitis, HIV, Human T-lymphotropic virus, Lyme disease, Neurosyphillis
Musculoskeletal / Ortho	No underlying causes
Neurologic	Achromatopsia , Alzheimer's disease, Corticobasal Degeneration, Creutzfeldt-Jakob disease, Encephalitis, Frontotemporal dementia, Hydrocephalus, Intractible epilepsy, Myelinopathies, Normal pressure hydrocephalus, Olivopontocerebellar Atrophy, Parkinson's disease, Pick's disease of the brain, Progressive supranuclear palsy, Right parietal lobe syndrome, Space occupying lesion, Subacute Sclerosing Panencephalitis, Transient global amnesia, Vertebrobasilar disease, Multi infarct dementia, Human T-lymphotropic virus, Neurosyphillis, Hypothalamus tumor, Tumors of the third ventricle, Dialysis encephalopathy syndrome, Neurosarcoidosis, Sneddon Syndrome
Nutritional / Metabolic	Vitamin B12 deficiecny, Dementia, Depression, Hyperthermia, Hypothermia, Hypoxia, Malabsorption, Megaloblastic Anemia , Nutritional deficiency, Pellagra, Thiamine deficiency, Wernicke-Korsakoff syndrome
Obstetric/Gynecologic	Menopause
Oncologic	Brain cancer, Hypothalamus tumor, Malignant astrocytoma, Malignant germ cell tumor, Tumors of the third ventricle
Opthalmologic	Achromatopsia
Overdose / Toxicity	No underlying causes
Psychiatric	Amnestic disorder, Chronic Fatigue Syndrome, Conversion disorder, Fugue states
Pulmonary	Hypoxia
Renal / Electrolyte	Dialysis encephalopathy syndrome, Hypercalcemia
Rheum / Immune / Allergy	Behcet's Disease, Neurosarcoidosis, Sneddon Syndrome
Sexual	No underlying causes
Trauma	Brain concussion, Head injury, Whiplash
Urologic	No underlying causes
Dental	No underlying causes
Miscellaneous	Alcoholism, Malingering

Causes in Alphabetical Order

• Achromatopsia

• AIDS Dementia Complex

• Alcoholism

• Aluminium poisoning

• Alzheimer's disease

• Amnestic disorder

• Anagrelide

• Anisotropine Methylbromide

• Anoxia

• Arteriovenous Malformation

• Barbiturate abuse

• Behcet's Disease

• Bilateral temporal lobectomy

• Brain cancer

• Brain Concussion

• Bromoform

• Cannabis

• Carbon monoxide poisoning

• Cerebrovascular accident

• Chronic Fatigue Syndrome

• Citrullinemia

• Conversion disorder

• Corticobasal Degeneration

• Creutzfeldt-Jakob disease

• Cryptococcal meningitis

• Dementia

• Depression

• Dialysis encephalopathy syndrome

• Diazepam

• Dicyclomine

• Down Syndrome

• Electroconvulsive therapy

• Encephalitis

• Flecainide

• Frontotemporal dementia

• Frostbite

• Fugue states

• Graeck-Imerslund disease

• Hashimoto's Thyroiditis

• Head injury

• Heat stroke

• Herpes simplex encephalitis

• HIV

• Hobo spider poisoning

• Human T-lymphotropic virus

• Hydrocephalus

• Hypercalcemia

• Hyperthermia

• Hyperthyroidism

• Hypothalamus tumor

• Hypothermia

• Hypothyroidism

• Hypoxia

• Intractible epilepsy

• Lamotrigine

• Levetiracetam

• Lyme disease

• Malabsorption

• Malignant astrocytoma

• Malignant germ cell tumor

• Malingering

• Megaloblastic Anemia

• Menopause

• Mercury poisoning

• Midazolam

• Modafinil

• Multi infarct dementia

• Myelinopathies

• Nefazodone

• Neurosarcoidosis

• Neurosyphillis

• Neurotoxicity syndromes

• Normal pressure hydrocephalus

• Nutritional deficiency

• Olivopontocerebellar Atrophy

• Oxcarbazepine

• Parkinson's disease

• Pellagra

• Phenelzine

• Pick's disease of the brain

• Pramipexole

• Progressive supranuclear palsy

• Right parietal lobe syndrome

• Ropinirole

• Selegiline

• Sneddon Syndrome

• Space occupying lesion

• Stachybotrys chartarum

• Subacute Sclerosing Panencephalitis

• Subarachnoid hemorrhage

• Temozolomide

• Thiamine deficiency

• Toluene

• Transient global amnesia

• Transient ischemic attack

• Trazodone

• Tumors of the third ventricle

• Valium

• Vertebrobasilar disease

• Vitamin B12 deficiecny

• Werknicke-Korsakoff syndrome

• Whiplash

• Zaleplon

• Zolpidem

Risk Factors

Normal aging may lead to trouble learning new material or requiring a longer time to remember learned material. However, it does not lead to dramatic memory loss unless diseases are involved.

Memory loss can be seen with impaired concentration, such as with depression. It can be hard to tell the difference.

Natural History, Complications, Prognosis

The cause determines whether amnesia comes on slowly or suddenly, and whether it is temporary or permanent.

Diagnosis

Symptoms

Symptoms of memory loss vary from person to person, but can include: forgetting dates and names; beginning a task but then forgetting the purpose of it; getting lost easily; repeating things over and over again, sometimes in the same conversation; and having difficulties performing familiar tasks such as driving or baking. They usually occur gradually and may vary in intensity depending on the cause of the condition.

Confusion or decreased alertness may be the first symptom of memory loss and also of serious illness, particularly in older adults.

The most worrisome symptoms are not those related to things that people forget to do.Template:Opinion Some patients may have problems mixing up or remembering words for objects or can have trouble understanding or taking part in a conversation. Being unable to make a simple decision can suggest that something is not working as it should and medical advice should be sought.

Whether an individual suffers from memory loss is not decided only based on one's symptoms. In order to diagnose the condition a doctor will obtain a detailed medical history of the patient. The patient will also undergo several neuropsychologicaltests that will focus on his or her memory functions. Several other medical exams such as anelectroencephalography, an MRI, or a CT scan can be performed in order to establish an accurate diagnosis.

The main type of memory loss is short-term memory. Short-term memory refers to memories that last for a few minutes.

History

Medical history questions may include:

• Type

• Can the person remember recent events (is there impaired short-term memory)?
• Can the person remember events from further in the past (is there impaired long-term memory)?
• Is there a loss of memory about events that occurred before a specific experience (anterograde amnesia)?
• Is there a loss of memory about events that occurred soon after a specific experience (retrograde amnesia)?
• Is there only a minimal loss of memory?
• Does the person make up stories to cover gaps in memory (confabulation)?
• Is the person suffering from low moods that impair concentration?

• Time pattern

• Has the memory loss been getting worse over years?
• Has the memory loss been developing over weeks or months?
• Is the memory loss present all the time or are there distinct episodes of amnesia?
• If there are amnesia episodes, how long do they last?

• Aggravating or triggering factors

• Has there been a head injury in the recent past?
• Has the person experienced an event that was emotionally traumatic?
• Has there been a surgery or procedure requiring general anesthesia?
• Does the person use alcohol? How much?
• Does the person use illegal/illicit drugs? How much? What type?

• Other symptoms

• What other symptoms does the person have?
• Is the person confused or disoriented?
• Can they independently eat, dress, and perform similar self-care activities?
• Have they had seizures?

Physical Examination

The physical examination includes a detailed test of thinking and memory (mental status or neurocognitive test), and an examination of the nervous system. Recent, intermediate, and long-term memory should be tested.

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)

References