What is amnesia?

Amnesia is when a person is unable to memorize or remember information stored in memory any more. It is very rare, despite being a popular theme for movies and books.

To be a little forgetful is completely different from having amnesia. Amnesia refers to a large-scale memory loss that should not have been overlooked.

These could include important life milestones, memorable events, key people in our lives, and vital facts that we were told or taught.

Important facts about amnesia

Here are a few key points regarding amnesia. The main article contains more details and supporting information.

  • Amnesia is an inability to lay down new memories, recall old memories, or both.
  • Other symptoms of amnesia can include confusion and uncoordinated movements.
  • Alcohol abuse can lead to a type of amnesia known as Wernicke-Korsakoff’s psychosis.
  • Amnesia can be caused by many things including traumatic experiences and brain injury.
  • Amnesia usually resolves without treatment.

What is amnesia?

Amnesia may result from a head injury.
Amnesia may result from a head injury.

Also, people with amnesia have difficulty remembering the past, memorizing new information and imagining the future. This is because based on our recollections of past experiences we construct future scenarios.

Our ability to recollect events and experiences involves a variety of complex brain processes. We still don’t understand exactly what happens when we commit something to memory or when we try to get the data stored in our brain back up.

Most amnesia sufferers are typically conscious and have a sense of self. However, they may experience severe difficulties in learning new information, struggle to recall memories of past experiences, or both.

Types

Amnesia occurs in several different forms. Below is a list of those that are most common:

  • Anterograde amnesia: The person cannot remember new information. Things that happened recently and information that should be stored into short-term memory disappear. This usually results from a brain trauma, when a blow to the head causes brain damage, for example. The person will remember data and events that happened before the injury.
  • Retrograde amnesia: In some ways the opposite of anterograde amnesia, the person cannot remember events that occurred before their trauma, but they remember what happened after it. Rarely, both retrograde and anterograde amnesia can occur together.
  • Transient global amnesia: 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.
  • Traumatic amnesia: Memory loss results from a hard blow to the head, for instance, in a car accident. 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.
  • Wernicke-Korsakoff’s psychosis: Extended alcohol abuse can lead to progressive memory loss that worsens over time. The person may also have neurological problems, such as poor coordination and a loss of feeling in the toes and fingers. It can also be caused by malnutrition, specifically a thiamin (vitamin B1) deficiency.
  • Hysterical (fugue or dissociative) amnesia: Rarely, a person can forget not only their past but also their identity. They may wake up and suddenly have no sense of who they are. Even if they look in the mirror, they do not recognize their own reflection. A driving license, credit cards, or ID card will be meaningless. It is usually triggered by an event that the person’s mind is unable to cope with properly. The ability to remember usually returns either slowly or suddenly within a few days, but the memory of the shocking event may never come back completely.
  • Childhood amnesia (infantile amnesia): The person cannot recall events from early childhood, possible because of a language development problem or some memory areas of the brain not fully maturing during childhood.
  • Posthypnotic amnesia: Events during hypnosis cannot be recalled.
  • Source amnesia: The person can remember certain information but not how or where they got that information.
  • Blackout phenomenon: A bout of heavy drinking can leave a person with memory gaps, where they cannot remember chunks of time during the binge.
  • Prosopamnesia: The person cannot remember faces. People can either acquire it or be born with it.

Symptoms

Amnesia symptoms
Amnesia is a rare condition.

The following are common symptoms of amnesia:

  • The ability to learn new information is impaired in anterograde amnesia.
  • The ability to remember past events and previously familiar information is impaired in retrograde amnesia
  • False memories may be either completely invented or consist of real memories misplaced in time, in a phenomenon known as confabulation.
  • Uncoordinated movements and tremors indicate neurological problems.
  • Confusion or disorientation may occur.
  • There may be problems with short-term memory, partial or total loss of memory
  • The person may be unable to recognize faces or locations.

Amnesia is far from dementia. Dementia requires memory loss but it also entails other serious cognitive problems that can impair the capacity of the patient to perform everyday activities.

Causes

Any brain-affecting illness or injury can interfere with memory. Memory function simultaneously engages several different parts of the brain.

Damage to the brain structures that shape the limbic system, such as hippocampus and thalamus, can contribute to amnesia. Our emotions and memories are controlled by the limbic system.

Medical amnesia

Amnesia resulting from brain injury or damage.

Possible causes are:

  • Stroke
  • Encephalitis, or brain inflammation, due to a bacterial or viral infection or an autoimmune reaction
  • Celiac disease may be linked to amnesia, confusion, and personality changes
  • Oxygen deprivation, resulting, for example, from a heart attack, respiratory distress, or carbon monoxide poisoning
  • Some medications, such as the sleeping drug, Ambien
  • 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
  • Some seizure disorders
  • Electroconvulsive therapy (ECT)), or electroshock therapy, a psychiatric treatment where seizures are induced for therapeutic effect, may lead to temporary memory loss
  • Head injuries, which can lead to loss of memory that is usually temporary

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

Any intolerable situation in life that causes severe psychological stress and internal conflict can lead to a certain amount of amnesia. Psychological stressors are more likely to interfere with personal, historical memories than with the laying down of new memories.

Diagnosis

A doctor will have to rule out other potential memory loss causes, including dementia, Alzheimer’s disease, depression, or a brain tumor.

They must take a detailed history of medication which can be difficult if the patient does not recall. It may be necessary to have family members or carers present.

The doctor will require the patient’s consent to speak to somebody about their medical details.

Questions can include:

  • Can the patient remember recent events and events further back in time?
  • When did the memory problems start?
  • How did they develop?
  • Could any factors have caused the memory loss, such as a head injury, surgery, or stroke?
  • Is there a family history of any neurological or psychiatric conditions?
  • Does the person consume alcohol?
  • Are they using any medication?
  • Have they taken illegal drugs, such as cocaine or heroin?
  • Are the symptoms undermining their ability to look after themselves?
  • Do they have a history of depression or seizures?
  • Have they ever had cancer?

A physical exam might include checking aspects of the brain and nervous system, such as:

  • reflexes
  • sensory function
  • balance

The doctor may also check the patient’s:

  • judgment
  • short-term memory
  • long-term memory

The memory assessment will help determine the magnitude of memory loss. This will aid in finding the best treatment.

The doctor may order MRI or CAT scans or an electroencephalogram (EEG) to find out if there is any physical damage or brain abnormality.

Blood testing can reveal any infections or nutritional deficiencies.

Treatment

Amnesia resolves itself untreated in most situations. However, treatment may be necessary when there is an underlying physical or mental disorder.

Psychotherapy may be of help to other patients. Hypnosis can be an effective means of restoring lost memories.

Support for the family is key. Photographs, smells, and music may help.

Treatment often involves techniques and strategies that will help offset the memory problem.

This may involve:

  • Working with an occupational therapist to acquire new information to replace lost memories, or to use existing memories as a basis for acquiring new information.
  • Learning strategies for organizing information, to make it easier to store.
  • Using digital aids, such as smartphones, to help with daily tasks and remind patients about important events, when to take medications, and so on. A contact list with photographs of faces may be helpful.

There are currently no medications available to recover lost memory due to amnesia.

Malnutrition or Wernicke-Korsakoff syndrome may involve memory loss due to a deficiency of thiamine (vitamin B1), so targeted nutrition can help.

Rich sources of thiamine are whole grain cereals, legumes (beans and lentils), nuts, lean pork, and yeast.

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