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''Amnesia''' is a complex neurological condition marked by impaired [[memory]] functions, often as a result of brain injury, disease, psychological trauma, or the use of certain medications. The primary manifestation of amnesia is the disturbance of memory, where patients may struggle to recall past events or find difficulty forming new memories. The specific form and severity of amnesia can vary greatly, depending on the underlying cause and the specific areas of the brain affected<ref>{{Cite web|url=http://www.emedicine.com/neuro/topic380.htm|title=Transient global amnesia|publisher=eMedicine}}</ref>.
{{SI}}
{{Infobox medical condition
| name = Amnesia
| synonyms = Amnesic syndrome
| image =
[[File:Noun Forget 1816.svg|Noun_Forget_1816]]
| image_size =
| caption = Depiction of memory impairment in amnesia
| field = [[Neurology]], [[Psychiatry]]
| symptoms = Memory loss, confusion, inability to retain new information
| complications = [[Cognitive impairment]], loss of autonomy, emotional distress
| onset = Sudden or gradual, depending on cause
| duration = Temporary or permanent
| types = [[Anterograde amnesia]], [[Retrograde amnesia]], [[Dissociative amnesia]], etc.
| causes = [[Brain injury]], [[stroke]], [[neurodegenerative disorders]], psychological trauma, [[alcohol abuse]]
| risks = Head trauma, [[epilepsy]], [[encephalitis]], substance use
| diagnosis = [[Neuropsychological testing]], [[MRI]], [[CT scan]], [[EEG]]
| differential = [[Dementia]], [[Delirium]], [[Depression]]
| prevention = Preventing head injuries, managing substance use, early intervention in infections
| treatment = Supportive care, cognitive rehabilitation, psychotherapy
| medication = [[Vitamin B1]] in cases like [[Korsakoff's syndrome]]
| prognosis = Varies by type and cause
| frequency = Uncommon overall; varies with underlying condition
| deaths = Rarely fatal directly
}}
 
'''Amnesia''' is a [[neurocognitive disorder]] characterized by partial or complete loss of [[memory]], either short-term, long-term, or both. It can result from a variety of causes including [[neurological]] damage, [[psychological trauma]], or [[toxic]] exposures. Individuals with amnesia may be unable to recall past experiences, form new memories, or both, depending on the type and extent of brain involvement.
 
== Classification ==
Amnesia is broadly categorized based on the type of memory affected and the underlying cause.


== Classification of Amnesia ==
=== Anterograde Amnesia ===
=== Anterograde Amnesia ===
[[Anterograde amnesia]] is a form of memory loss where the ability to create new memories post-amnesia onset is impaired, while past memories remain intact. People with anterograde amnesia often forget events shortly after they occur and struggle to retain new information for longer periods.
[[Anterograde amnesia]] is the inability to form new memories following the onset of the condition, often caused by damage to the [[hippocampus]] or related structures.


=== Retrograde Amnesia ===
=== Retrograde Amnesia ===
Contrasting with anterograde amnesia, [[retrograde amnesia]] presents as an inability to recall events that happened before the onset of amnesia. Despite this, the ability to form new memories remains unaltered.
[[Retrograde amnesia]] involves the loss of pre-existing memories prior to the onset of amnesia. It often spares older memories while more recent ones are affected.


=== Traumatic Amnesia ===
=== Transient Global Amnesia ===
[[Traumatic amnesia]] is a temporary or permanent memory loss induced by a physical injury to the brain, such as a concussion. The severity and duration of amnesia correlate with the extent of the injury.
[[Transient global amnesia]] (TGA) is a sudden, temporary episode of memory loss not attributable to more common neurological conditions like [[epilepsy]] or [[stroke]].


=== Dissociative Amnesia ===
=== Dissociative Amnesia ===
In [[dissociative amnesia]], long-term memories, typically associated with traumatic or stressful events, are repressed. This condition, deeply intertwined with mental health, is often seen in patients with post-traumatic stress disorder (PTSD).
[[Dissociative amnesia]] is typically psychological in origin, where individuals block out memories related to stressful or traumatic events. It is associated with [[post-traumatic stress disorder]] (PTSD) and [[dissociative disorders]].
 
=== Traumatic Amnesia ===
Often seen after head injuries, [[traumatic amnesia]] may involve both retrograde and anterograde memory loss, depending on the severity of the [[traumatic brain injury]].


=== Korsakoff's Syndrome ===
=== Korsakoff's Syndrome ===
Chronic alcohol abuse can lead to a specific type of memory loss known as [[Korsakoff's syndrome]]. This condition stems from vitamin B1 deficiency leading to brain damage. Korsakoff's syndrome generally manifests as progressive memory loss and cognitive decline if alcohol consumption continues and nutritional deficiencies persist.
[[Korsakoff's syndrome]] is a chronic memory disorder caused by severe deficiency of [[vitamin B1]] (thiamine), most often due to chronic [[alcoholism]].


=== Lacunar Amnesia ===
=== Lacunar Amnesia ===
[[Lacunar amnesia]] describes memory loss specific to a singular event or small span of time. Individuals with this form of amnesia typically maintain a normal memory function outside of this specific 'gap' in their memory.
[[Lacunar amnesia]] refers to memory loss of a specific event, leaving the rest of memory intact. It may occur in cases of [[stroke]] or localized brain trauma.


=== Fugue State ===
=== Fugue State ===
Also known as [[dissociative fugue]], this type of amnesia is characterized by temporary, often sudden, memory loss related to one's identity or history. This form of amnesia is usually associated with severe psychological trauma.
Also known as [[dissociative fugue]], this condition involves sudden, unplanned travel away from home combined with memory loss regarding personal identity.


=== Childhood or Infantile Amnesia ===
=== Infantile Amnesia ===
[[Childhood amnesia]], also known as infantile amnesia, describes the general inability of adults to recall events from early childhood. The exact cause is debated, with theories ranging from language development processes to the immaturity of certain brain regions during early life.
Also referred to as [[childhood amnesia]], it is the normal inability of adults to recall memories from the early years of life, typically before age three.
 
=== Global Amnesia ===
[[Global amnesia]] is a severe form of memory loss, resulting in complete or near-complete inability to recall past events or form new memories. This form of amnesia is often associated with significant trauma.
 
=== Posthypnotic Amnesia ===
[[Posthypnotic amnesia]] involves the inability to recall events or information encountered while under hypnosis. This form of amnesia is usually temporary and reversible.


=== Psychogenic Amnesia ===
=== Psychogenic Amnesia ===
[[Psychogenic amnesia]], unlike organic amnesia, is not due to direct physical damage to the brain. Instead, it is caused by psychological factors, often related to stress or trauma.
[[Psychogenic amnesia]] is caused by emotional trauma or psychological conflict, without any detectable brain injury.


=== Source Amnesia ===
=== Source Amnesia ===
[[Source amnesia]] is a specific type of memory disorder where an individual can remember certain information, but cannot recall how or where they learned it.
[[Source amnesia]] refers to the inability to remember the origin or source of learned information while retaining the factual content.


=== Memory Distrust Syndrome ===
=== Alcohol-Induced Amnesia ===
[[Memory distrust syndrome]] is a term coined by psychologist [[Gisli Gudjonsson]] to characterize a condition where a person is unable to trust their own memory. This syndrome often presents in individuals who question the authenticity of their recollections and can be seen in various psychological and neurological disorders.
Also called [[blackout (alcohol-related amnesia)|alcohol-induced blackouts]], these are temporary memory lapses caused by excessive alcohol consumption.


=== Alcohol-induced Amnesia ===
== Causes ==
Also known as "blackouts," short-term excessive alcohol consumption can induce symptoms akin to amnesia. This condition often results in an inability to recall events that occurred while under the influence of alcohol.
Amnesia can arise from:
* [[Brain injury]] (trauma, surgery)
* [[Stroke]]
* [[Infection]]s such as [[encephalitis]]
* [[Neurodegenerative disease]]s like [[Alzheimer's disease]]
* [[Psychological trauma]]
* [[Anesthesia]] or sedation
* Substance abuse, particularly [[alcohol]]


== Causes and Mechanisms ==
Damage to brain regions involved in memory processing — especially the [[hippocampus]], [[thalamus]], [[prefrontal cortex]], and [[amygdala]] — is typically implicated in organic amnesia.


Amnesia can have both organic and functional causes. Organic causes involve direct damage to the brain from physical trauma, disease, or certain medications, particularly those with sedative effects. Functional causes are usually psychological, such as defense mechanisms employed following traumatic experiences.
== Diagnosis ==
Diagnosis involves a combination of:
* Detailed [[clinical history]]
* [[Neurological examination]]
* [[Neuropsychological tests]]
* [[Magnetic resonance imaging|MRI]] or [[computed tomography|CT scan]]
* [[Electroencephalogram|EEG]] (to rule out seizures)


The neuroanatomical basis of amnesia often centers around damage to brain structures critical for memory processing and storage, particularly the medial [[temporal lobe|temporal lobes]] and the [[hippocampus]]. The pattern of memory loss—whether it affects old memories or the formation of new ones—can help localize the brain damage and identify the type of amnesia.
== Treatment ==
 
Treatment depends on the cause:
== Treatment and Management ==
* '''Reversible causes''' (e.g., vitamin deficiency or medication side effects) are treated by correcting the underlying condition.
 
* '''Cognitive therapy''': Occupational therapy and memory training strategies can help patients adapt.
The treatment for amnesia is contingent on its underlying cause. Addressing the root cause may lead to an improvement in memory function. For instance, if the amnesia is drug-induced, discontinuing the drug usually leads to improvement. In the case of vitamin deficiency, like in Korsakoff's syndrome, vitamin supplementation and improving diet can help.
* '''Psychotherapy''': Used in dissociative or psychogenic amnesia to uncover and address underlying trauma.
 
* '''Pharmacotherapy''': In some cases, medications to treat underlying conditions (e.g., antidepressants for PTSD-related amnesia) may be used.
In other cases, treatment involves supportive care and rehabilitation to help the person cope with the condition. Memory training and occupational therapy can often be of substantial benefit. In the case of psychological forms of amnesia like dissociative amnesia, therapy or counseling may be necessary.


== Prognosis ==
== Prognosis ==
The outcome of amnesia depends on its cause and severity:
* Temporary amnesia (e.g., from minor head trauma or stress) often resolves completely.
* Chronic or progressive causes (e.g., Korsakoff’s syndrome, Alzheimer's) may lead to permanent memory loss.
* Psychological forms may improve with therapy.


The prognosis for amnesia varies widely and depends on the cause and the severity of the memory impairment. Some forms of amnesia, such as those caused by minor head injuries or transient global amnesia, are temporary and self-limiting. Others, such as amnesia from severe brain injury or progressive neurological disease, may be permanent.
== See also ==
 
* [[Memory]]
The impact of amnesia on a person’s life depends on its severity and the person’s individual circumstances. Some people can lead relatively normal lives, while others require full-time care.
* [[Hippocampus]]
* [[Neuropsychology]]
* [[Dementia]]
* [[Cognitive rehabilitation]]
* [[Wernicke–Korsakoff syndrome]]
* [[Brain plasticity]]


== Summary ==
== External links ==
Amnesia is a complex and diverse condition, encompassing a range of memory disturbances. Further understanding of the mechanisms and causes underlying these various types of amnesia can aid in the development of more effective treatments and interventions, thereby improving the quality of life for those affected.
* [https://www.ninds.nih.gov/health-information/disorders/amnesia National Institute of Neurological Disorders and Stroke – Amnesia]
* [https://medlineplus.gov/amnesia.html MedlinePlus – Amnesia Overview]


== See also ==
* [[Betrayal#Political Betrayal Trauma|Betrayal Trauma]]
* [[Clive Wearing]]
* [[Emotion and memory]]
* [[HM (patient)]]
* [[Phip Staufen|Mr. Nobody]]
* [http://www.psychnet-uk.com/dsm_iv/dissociative_amnesia.htm Psychnet UK, Treatment]
{{stub}}
== References ==
<references/>
[[Category:Neurological disorders]]
[[Category:Neurological disorders]]
[[Category:Memory]]
[[Category:Neuropsychology]]
[[Category:Neuropsychology]]
[[Category:Memory disorders]]
[[Category:Psychiatry]]
[[Category:Psychiatry]]
{{No image}}

Revision as of 02:17, 31 March 2025

Editor-In-Chief: Prab R Tumpati, MD
Obesity, Sleep & Internal medicine
Founder, WikiMD Wellnesspedia &
W8MD medical weight loss NYC and sleep center NYC

Amnesia
Noun_Forget_1816
Synonyms Amnesic syndrome
Pronounce N/A
Specialty N/A
Symptoms Memory loss, confusion, inability to retain new information
Complications Cognitive impairment, loss of autonomy, emotional distress
Onset Sudden or gradual, depending on cause
Duration Temporary or permanent
Types Anterograde amnesia, Retrograde amnesia, Dissociative amnesia, etc.
Causes Brain injury, stroke, neurodegenerative disorders, psychological trauma, alcohol abuse
Risks Head trauma, epilepsy, encephalitis, substance use
Diagnosis Neuropsychological testing, MRI, CT scan, EEG
Differential diagnosis Dementia, Delirium, Depression
Prevention Preventing head injuries, managing substance use, early intervention in infections
Treatment Supportive care, cognitive rehabilitation, psychotherapy
Medication Vitamin B1 in cases like Korsakoff's syndrome
Prognosis Varies by type and cause
Frequency Uncommon overall; varies with underlying condition
Deaths Rarely fatal directly


Amnesia is a neurocognitive disorder characterized by partial or complete loss of memory, either short-term, long-term, or both. It can result from a variety of causes including neurological damage, psychological trauma, or toxic exposures. Individuals with amnesia may be unable to recall past experiences, form new memories, or both, depending on the type and extent of brain involvement.

Classification

Amnesia is broadly categorized based on the type of memory affected and the underlying cause.

Anterograde Amnesia

Anterograde amnesia is the inability to form new memories following the onset of the condition, often caused by damage to the hippocampus or related structures.

Retrograde Amnesia

Retrograde amnesia involves the loss of pre-existing memories prior to the onset of amnesia. It often spares older memories while more recent ones are affected.

Transient Global Amnesia

Transient global amnesia (TGA) is a sudden, temporary episode of memory loss not attributable to more common neurological conditions like epilepsy or stroke.

Dissociative Amnesia

Dissociative amnesia is typically psychological in origin, where individuals block out memories related to stressful or traumatic events. It is associated with post-traumatic stress disorder (PTSD) and dissociative disorders.

Traumatic Amnesia

Often seen after head injuries, traumatic amnesia may involve both retrograde and anterograde memory loss, depending on the severity of the traumatic brain injury.

Korsakoff's Syndrome

Korsakoff's syndrome is a chronic memory disorder caused by severe deficiency of vitamin B1 (thiamine), most often due to chronic alcoholism.

Lacunar Amnesia

Lacunar amnesia refers to memory loss of a specific event, leaving the rest of memory intact. It may occur in cases of stroke or localized brain trauma.

Fugue State

Also known as dissociative fugue, this condition involves sudden, unplanned travel away from home combined with memory loss regarding personal identity.

Infantile Amnesia

Also referred to as childhood amnesia, it is the normal inability of adults to recall memories from the early years of life, typically before age three.

Psychogenic Amnesia

Psychogenic amnesia is caused by emotional trauma or psychological conflict, without any detectable brain injury.

Source Amnesia

Source amnesia refers to the inability to remember the origin or source of learned information while retaining the factual content.

Alcohol-Induced Amnesia

Also called alcohol-induced blackouts, these are temporary memory lapses caused by excessive alcohol consumption.

Causes

Amnesia can arise from:

Damage to brain regions involved in memory processing — especially the hippocampus, thalamus, prefrontal cortex, and amygdala — is typically implicated in organic amnesia.

Diagnosis

Diagnosis involves a combination of:

Treatment

Treatment depends on the cause:

  • Reversible causes (e.g., vitamin deficiency or medication side effects) are treated by correcting the underlying condition.
  • Cognitive therapy: Occupational therapy and memory training strategies can help patients adapt.
  • Psychotherapy: Used in dissociative or psychogenic amnesia to uncover and address underlying trauma.
  • Pharmacotherapy: In some cases, medications to treat underlying conditions (e.g., antidepressants for PTSD-related amnesia) may be used.

Prognosis

The outcome of amnesia depends on its cause and severity:

  • Temporary amnesia (e.g., from minor head trauma or stress) often resolves completely.
  • Chronic or progressive causes (e.g., Korsakoff’s syndrome, Alzheimer's) may lead to permanent memory loss.
  • Psychological forms may improve with therapy.

See also

External links

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