Amnesia - Wikipedia, the free encyclopedia
Amnesia
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For other uses, see Amnesia (disambiguation).
Not to be confused with memory loss.
Amnesia
Classification and external resources
ICD-10
F04, R41.3
ICD-9
294.0, 780.9, 780.93
MeSH
D000647
Amnesia (from Greek ?¦Ì¦Í¦Ç¦Ò?¦Á) is a condition in which one's memory is lost. The causes of amnesia have traditionally been divided into categories. Functional causes are psychological factors, such as mental disorder, post-traumatic stress or, in psychoanalytic terms, defense mechanisms. Amnesia may also appear as spontaneous episodes, in the case of transient global amnesia.[1]
Anterograde amnesia, is the loss of short-term memory, the loss or impairment of the ability to form new memories through memorization. People may find themselves constantly forgetting a piece of information, people or events after a few seconds or minutes, because the data does not transfer successfully from their conscious short-term memory into permanent long-term memory.
Retrograde amnesia, the loss of pre-existing memories to conscious recollection, beyond an ordinary degree of forgetfulness. The person may be able to memorize new things that occur after the onset of amnesia (unlike in anterograde amnesia), but is unable to recall some or all of their life or identity prior to the onset.
However, there are different types of memory, for example procedural memory (i.e. automated skills) and declarative memory (personal episodes or abstract facts), and often only one type is impaired. For example, a person may forget the details of personal identity, but still retain a learned skill such as the ability to play the piano.
In addition, the terms are used to categorize patterns of symptoms rather than to indicate a particular cause (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 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).
The effects of amnesia can last long after the condition has passed. Some sufferers claim that their amnesia changes from a neurological condition to also being a psychological condition, whereby they lose confidence and faith in their own memory and accounts of past events.
Another effect of some forms of amnesia may be impaired ability to imagine future events. A 2006 study showed that future experiences imagined by amnesiacs with bilaterally damaged hippocampus lacked spatial coherence, and the authors speculated that the hippocampus may bind different elements of experience together in the process of re-experiencing the past or imagining the future.[2]
[edit] Types and causes of 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.
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." [3] 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. Sigmund Freud notoriously attributed this to sexual repression, while modern scientific approaches generally attribute it to aspects of brain development or developmental psychology, including language development
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.
Drug-induced amnesia is intentionally caused by injection of an amnesiac drug to help a patient forget surgery or medical procedures, particularly those not performed under full anesthesia, or likely to be particularly traumatic. Such drugs are also referred to as "premedicants." Most commonly a 2'-halogenated benzodiazepine such as midazolam or flunitrazepam is the drug of choice, although other strongly amnestic drugs such as propofol or scopolamine may also be used for this application. Memories of the short time frame in which the procedure was performed are permanently lost or at least substantially reduced, but once the drug wears off, memory is no longer affected.
Electroconvulsive therapy in which seizures are electrically induced in patients for therapeutic effect can have acute effects including both retrograde and anterograde amnesia.
Prosopamnesia is the inability to remember faces, even in the presence of intact facial recognition capabilities. Both acquired and inborn cases have been documented.
Situation-Specific amnesia can arise in a variety of circumstances (e.g., committing an offence, child sexual abuse) resulting in PTSD. It has been claimed that it involves a narrowing of consciousness with attention focused on central perceptual details and/or that the emotional or traumatic events are processed differently from ordinary memories.
[edit] See also
Betrayal Trauma
Doug Bruce
Emotion and memory
False memory
HM (patient)
KC (patient)
Benjaman Kyle
Repressed memories
Mr. Nobody
Transient epileptic amnesia (TEA)
Clive Wearing
List of films featuring mental illness
[edit] References
Notes
^ eMedicine - Transient Global Amnesia : Article by Roy Sucholeiki
^ Patients with hippocampal amnesia cannot imagine new experiences, Proceedings of the National Academy of Sciences.
^ The Merck Manuals Online
Articles and topics related to Amnesia
v ¡¤ d ¡¤ eMental and behavioral disorders (F ¡¤ 290¨C319)
Neurological/symptomatic
Dementia
Mild cognitive impairment ¡¤ Alzheimer's disease ¡¤ Multi-infarct dementia ¡¤ Pick's disease ¡¤ Creutzfeldt¨CJakob disease ¡¤ Huntington's disease ¡¤ Parkinson's disease ¡¤ AIDS dementia complex ¡¤ Frontotemporal dementia ¡¤ Sundowning, Wandering
Other
Delirium ¡¤ Post-concussion syndrome ¡¤ Organic brain syndrome
Psychoactive substances, substance abuse, drug abuse and substance-related disorders
Intoxication/Drug overdose ¡¤ Physical dependence ¡¤ Substance dependence ¡¤ Rebound effect ¡¤ Double rebound ¡¤ Withdrawal
Schizophrenia, schizotypal and delusional
Psychosis (Schizoaffective disorder, Schizophreniform disorder, Brief reactive psychosis) ¡¤ Schizophrenia (Disorganized schizophrenia, Delusional disorder, Folie ¨¤ deux)
Mood (affective)
Mania ¡¤ Bipolar disorder (Bipolar I, Bipolar II, Cyclothymia, Bipolar NOS) ¡¤ Depression (Major depressive disorder, Dysthymia, Seasonal affective disorder, Atypical depression, Melancholic depression)
Neurotic, stress-related and somatoform
Anxiety disorder
Phobia
Agoraphobia ¡¤ Social anxiety/Social phobia (Anthropophobia) ¡¤ Specific phobia (Claustrophobia) ¡¤ Specific social phobia
Other
Panic disorder/Panic attack ¡¤ Generalized anxiety disorder ¡¤ OCD ¡¤ stress (Acute stress reaction, PTSD)
Adjustment disorder
Adjustment disorder with depressed mood
Somatoform disorder
Somatization disorder ¡¤ Body dysmorphic disorder ¡¤ Hypochondriasis ¡¤ Nosophobia ¡¤ Da Costa's syndrome ¡¤ Psychalgia ¡¤ Conversion disorder (Ganser syndrome, Globus pharyngis) ¡¤ Neurasthenia ¡¤ Mass Psychogenic Illness
Dissociative disorder
Dissociative identity disorder ¡¤ Psychogenic amnesia ¡¤ Fugue state ¡¤ Depersonalization disorder
Physiological/physical behavioral
Eating disorder
Anorexia nervosa ¡¤ Bulimia nervosa ¡¤ Rumination syndrome ¡¤ NOS
Nonorganic
sleep disorders
(Nonorganic hypersomnia, Nonorganic insomnia) ¡¤ Parasomnia (REM behavior disorder, Night terror, Nightmare)
Sexual
dysfunction
sexual desire (Hypoactive sexual desire disorder, Hypersexuality) ¡¤ sexual arousal (Female sexual arousal disorder) ¡¤ Erectile dysfunction ¡¤ orgasm (Anorgasmia, Delayed ejaculation, Premature ejaculation, Sexual anhedonia) ¡¤ pain (Vaginismus, Dyspareunia)
Postnatal
Postpartum depression ¡¤ Postnatal psychosis
Adult personality and behavior
Sexual and
gender identity
Sexual maturation disorder ¡¤ Ego-dystonic sexual orientation ¡¤ Sexual relationship disorder ¡¤ Paraphilia (Voyeurism, Fetishism)
Other
Personality disorder ¡¤ Impulse control disorder (Kleptomania, Trichotillomania, Pyromania, Dermatillomania) ¡¤ Body-focused repetitive behavior ¡¤ Factitious disorder (M¨¹nchausen syndrome)
Mental disorders diagnosed in childhood
Mental retardation
X-Linked mental retardation (Lujan-Fryns syndrome)
Psychological development
(developmental disorder)
Specific ¡¤ Pervasive
Emotional and behavioral
ADHD ¡¤ Conduct disorder (ODD) ¡¤ emotional disorder (Separation anxiety disorder) ¡¤ social functioning (Selective mutism, RAD, DAD) ¡¤ Tic disorder (Tourette syndrome) ¡¤ Speech (Stuttering, Cluttering) ¡¤ Movement disorder (Stereotypic)
Symptoms and uncategorized
Catatonia ¡¤ False pregnancy ¡¤ Intermittent explosive disorder ¡¤ Psychomotor agitation ¡¤ Sexual addiction ¡¤ Stereotypy ¡¤ Psychogenic non-epileptic seizures ¡¤ Kl¨¹ver-Bucy syndrome
M: PSO/PSI
mepr
dsrd (o, p, m, p, a, d, s), sysi/epon, spvo
proc(eval/thrp), drug(N5A/5B/5C/6A/6B/6D)
v ¡¤ d ¡¤ eSymptoms and signs: cognition, perception, emotional state and behaviour (R40¨CR46, 780.0¨C780.5, 781.1)
Cognition
Alteration of
consciousness
Confusion (Delirium) ¡¤ Somnolence ¡¤ Obtundation ¡¤ Stupor ¡¤ Unconsciousness (Syncope, Coma, Persistent vegetative state)
Fainting/Syncope
Carotid sinus syncope ? Heat syncope ? Vasovagal episode
Other
Amnesia (Anterograde amnesia, Retrograde amnesia) ¡¤ Dizziness (Vertigo, Presyncope/Lightheadedness, Disequilibrium) ¡¤ Convulsion
Emotional state
Anxiety ¡¤ Irritability ¡¤ Hostility ¡¤ Suicidal ideation
Behavior
Verbosity
Perception/
sensation
disorder
Olfaction : Anosmia ¡¤ Hyposmia ¡¤ Dysosmia ¡¤ Parosmia ¡¤ Hyperosmia
Taste: Ageusia ¡¤ Hypogeusia ¡¤ Dysgeusia ¡¤ Parageusia ¡¤ Hypergeusia
Hallucination: Auditory hallucination
M: PSO/PSI
mepr
dsrd (o, p, m, p, a, d, s), sysi/epon, spvo
proc(eval/thrp), drug(N5A/5B/5C/6A/6B/6D)
M: OLF
anat, recp
sysi
-
M: TST
anat, phys
sysi
-
v ¡¤ d ¡¤ eMemory
Basic concepts
Encoding ? Storage ? Recall
Attention ? Memory consolidation ? Neuroanatomy of memory
Long-term memory
Active recall ? Autobiographical memory ? Declarative memory ? Episodic memory ? Explicit memory ? Flashbulb memory ? Hyperthymesia ? Implicit memory ? Procedural memory ? Rote learning ? Selective retention ? Semantic memory ? Tip of the tongue
Short-term memory
"The Magical Number Seven, Plus or Minus Two" ? Working memory
Sensory memory
Echoic memory ? Eidetic memory ? Iconic memory ? Motor learning ? Visual memory
Forgetting
Amnesia ? Anterograde amnesia ? Childhood amnesia ? Decay theory ? Forgetting curve ? Interference theory ? Memory inhibition ? Motivated forgetting ? Post-traumatic amnesia ? Psychogenic amnesia ? Repressed memory ? Retrograde amnesia ? Selective memory loss ? Transient global amnesia ? Weapon focus
Research
Art of memory ? Memory and aging ? Exceptional memory ? Indirect tests of memory ? Lost in the mall technique ? Memory disorder ? Methods used to study memory ? Reconstruction of automobile destruction ? The Seven Sins of Memory
Related concepts
Absent-mindedness ? Atkinson¨CShiffrin memory model ? Confabulation ? Context-dependent memory ? Cryptomnesia ? Effect of Alcohol on Memory ? Emotion and memory ? Exosomatic memory ? Flashbacks ? Free recall ? Involuntary memory ? Levels-of-processing effect ? List of memory biases ? Memory and aging ? Memory for the future ? Memory and trauma ? Metamemory ? Mnemonic ? Muscle memory ? Priming ? Prospective memory ? Recovered memory therapy ? Retrospective memory ? Sleep and Memory ? Source-monitoring error ? Memory improvement
Culture and society
Cultural memory ? False memory syndrome ? Politics of memory ? Shass Pollak ? Transactive memory ? Memory and social interactions ? Memory sport ? World Memory Championships
Notable people
Robert A. Bjork ? Stephen J. Ceci ? Susan Clancy ? Hermann Ebbinghaus ? Sigmund Freud ? Patricia Goldman-Rakic ? Jonathan Hancock ? Judith Lewis Herman ? HM (patient) ? Ivan Izquierdo ? Marcia K. Johnson ? Eric Kandel ? KC (patient) ? Elizabeth Loftus ? Geoffrey Loftus ? James McGaugh ? Paul R. McHugh ? George Armitage Miller ? Brenda Milner ? Lynn Nadel ? Dominic O'Brien ? Ben Pridmore ? Henry L. Roediger III ? Steven Rose ? Cosmos Rossellius ? Daniel Schacter ? Richard Shiffrin ? Arthur P. Shimamura ? Andriy Slyusarchuk ? Larry Squire ? Susumu Tonegawa ? Anne Treisman ? Endel Tulving ? Robert Stickgold
Retrieved from "http://en.wikipedia.org/w/index.php?title=Amnesia&oldid=461034128"
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