What Is Amnesia?

The term amnesia consists of false addition, unintentional exclusion, less common but extensive and provoked confabulations (unintentional letting false information, providing, or describing wrong information not to deceive) of things, places, names, or anything linked to humans. This condition comes up when a person can not access his memory due to failure of interference or brain monitoring.

Overview

The term Global Amnesia does not involve any harshness, it is identified as verbal and non-verbal communication memory loss. Cognitive memory impairment is not present in amnesia, it only involves recall and recognition deficit. Amnesia is the loss of explicit long-term memory, which means that in order to remember, you have to think back to the learning phase.

Implicit learning and memory, as well as short-term memory, are not affected. Procedural and semantic memory, on the other hand, may be unaffected or only mildly affected.1

Types of Amnesia

There are two main types of amnesia.

Neurogenic amnesia is caused by brain lesions, while psychogenic amnesia is caused by psychological factors.

Further types of amnesia are given below:

Retrograde amnesia

When it talks about the time before the disease, it means that there was a problem with the person's autobiographical memory, which is also called the story of their own life. This kind of memory loss is called "retrograde amnesia."2

Anterograde amnesia

Anterograde amnesia refers to episodic memory (memory for specific personal experiences and newly learned information) that is impaired in the period following the onset of the disease. Disease can be organic or psychogenic.3

Transient global amnesia (TGA)

Patients with transient global amnesia (TGA) have anterograde amnesia, which means they can't store new memories for up to 24 hours. This is accompanied by repeated questioning and sometimes a retrograde component.

Dissociative amnesia

There have been reports of dissociative amnesias resulting from neurological events that were not severe enough to leave any visible morphological scars. Disproportionate retrograde amnesia, identity loss, or both are possible outcomes of known or unknown psychological trauma.

Despite normal morphological imaging, metabolic imaging studies have shown functional changes, particularly on both sides of the hippocampus, in the right temporal region, and in the inferior prefrontal cortex. The researchers De Renzi and colleagues came up with the term "functional amnesia" in order to get around the assumption that such changes have an organic, psychogenic, or mixed origin.

Patients have sometimes recovered in a spectacular way, while other times they have never recovered during events that were similar to those that occurred before the amnesia.

Sedation or distraction can help with the start of the healing process in some cases. It was discovered during psychotherapy that one of the patient's patients had been present when the car caught fire when they were children, and that the patient's amnesia had begun when their home burned down. Repression obscures amnesic traces in the new emotional and biological context, effectively blocking amnesia. This suggests that the source of control is the frontal cortex.

Post-traumatic amnesia (PTA)

Most people who go to a hospital for treatment of traumatic brain injury (TBI) have a state of altered consciousness called "post-traumatic amnesia" (PTA). Even though there isn't a single, agreed-upon definition of the term "PTA," it is often used in neurosurgery to help make decisions and predict outcomes. It is important to have an accurate assessment of the PTA because an over-evaluation can lead to extra social, financial, and opportunity costs, while an under-evaluation can put patient welfare at risk. Even though PTA also affects anterograde memory, it does so in a much bigger way. More importantly, the full "post-TBI syndrome" also includes a significant cognitive deficit, which may include a state of confusion, as well as a change in behaviour that is marked by extreme agitation. Because TBIs can cause damage to the brain. Attention and executive functioning problems have been getting a lot of attention lately. In fact, some people think that these are the main problems with PTA. Even though all these symptoms were fully described (or hinted at) by the first researchers, most of the PTA scores used today do not measure the full "post-TBI syndrome."

Infantile or childhood amnesia

Amnesia of childhood refers to the inability of a person, whether they are an adult or a child, to recall experiences from their formative years. Although subsequent empirical investigations have confirmed many of the original observations, they have not confirmed Freud's explanation for the phenomenon; however, he was the one who first coined the term. According to Freud's theory, there are not just one but at least two distinct stages of amnesia that occur during childhood. It is not a single phenomenon.

According to the results of a study that disproves Freud's idea that repression is the cause of childhood amnesia, a full explanation of childhood amnesia will need to take into account neurological, cognitive, linguistic, and social development.

Sigmund Freud, writing in the late 1800s, came up with the term "infantile amnesia" to describe the inability of individuals to remember events that occurred during their infancy or early childhood. Infantile amnesia presents a paradox in that adults have surprisingly few memories of their early childhood. This is the case despite the fact that young children appear to have an exuberant capacity for learning. Is there any way that these results can be squared away? There is more than one theory that attempts to explain how this form of amnesia can take place. According to psychological and cognitive theories, the development of language, theory of mind, and/or a sense of "self" is linked to the long-term retention of declarative-like memories. On the other hand, the fact that infantile amnesia can be observed in animals lends credence to the idea that this phenomenon cannot be completely explained using human concepts. The biological explanations of infantile amnesia suggest that the prolonged postnatal development of key brain regions that are important for memory interferes with stable long-term memory storage. However, these biological explanations do not clearly specify which aspects of brain maturation are causally related to infantile amnesia.

Drug-induced amnesia

Patients suffering from amnesia have difficulty recalling past events consciously, but they perform well on tests of implicit memory, which do not require access to the patient's past in order to be successful. Amnesia, even when temporarily induced in healthy subjects through the use of a neuropharmacological manipulation, may impair even implicit memory, according to recent research that was published in the journal Neuropsychopharmacology for example midazolam. Midazolam had no effect on non-relational memory, but it did have an adverse effect on implicit relational memory. This lends credence to the theory that conscious memory is founded not on simple encoding but on implicit relational encoding.

Prosopamnesia

A study is of the opinion that the structures that are necessary for representing what has already been learned are distinct from the structures that are necessary for new learning. According to this counterintuitive division of labour and the localised nature of knowledge representation for at least some stimuli domains, disconnection between learning mechanisms and domain-specific representations can lead to new learning impairments. This can occur because of the localised nature of knowledge representation. A condition in which a person has lost the ability to recognise faces for the first time is referred to as "prosopamnesia," and this study describes it using the term "prosopamnesia." A person must be able to recognise faces that they were familiar with prior to their illness in order to be diagnosed as having a form of prosopamnesia. Additionally, the person must be able to recognise new faces that they have never seen before. Using these criteria, the researchers describe a patient who satisfies them. This helps to support the division of labour between neural systems that are responsible for learning and neural systems that are responsible for the representation of knowledge. It also provides additional support for the segmented representation of faces in the cortex. 

Developmental Amnesia

Episodic amnesia with preserved semantic memory that occurs after hypoxic-ischaemic events that typically occur within the first year of a person's life.

Causes of Amnesia

There may be medical or psychological causes of Amnesia.

Medical causes of amnesia are as follows:

  1. Ischaemic or haemorrhagic stroke
  2. Bleeding due to aneurysm like subarachnoid haemorrhage or aneurysm surgery.
  3. Closed or penetrating head injury.
  4. Tumour present intracranially.
  5. Amnesia can be caused by limbic encephalitis. This disease is caused by herpes simplex virus 1 &2, herpes zoster virus. This condition may be associated with autoimmune disease e.g., systemic lupus erythematous, Encephalitis linked with voltage gated potassium channel antibody.
  6. Neurosyphilis
  7. Vitamin B1 deficiency can also cause amnesia.
  8. Transient epileptic amnesia

Substance related causes of Amnesia are mentioned below:

  1. Chronic alcohol use can cause vitamin B1 deficiency. It can cause Amnesia and termed as Korsakoff ’s syndrome.
  2. Misuse of anxiolytics, sedative and hypnotics like benzodiazepines, barbiturate and zolpidem can cause amnesia.
  3. Anticholinergic drugs like tricyclic and tetracyclic antidepressants can cause amnesia.

Psychological causes

  • Stress
  • Insomnia (Lack of sleep)
  • Anxiety or depression

Symptoms of amnesia

Amnesia, rather than being a separate entity in and of itself, was found to be a symptom during the course of an investigation, which led to this finding. It can be brought on by a wide variety of organic conditions that affect the central nervous system, including epilepsy, brain tumours, and head trauma. Addiction to drugs or alcohol is another potential cause of this condition. There is also the possibility that this is an early sign of schizophrenia in its developmental stage.

Diagnosis

In order to help narrow down the possibilities for a differential diagnosis, following methods are adopted.

Medical history

The presence of symptoms of a neurologic disease or a history of epilepsy, alcoholism, drug use, or a head injury are taken into consideration. In some cases, the presence of amnesia is associated with the manifestation of psychotic symptoms

Physical exam

The neurological exam measures reflexes, sensory function, balance, and other aspects of the brain and nervous system. Neurological examinations may be included in the physical examination.

Cognitive tests

The physician will evaluate the patient's capacity for reasoning and judgement, as well as their ability to recall both recent and long-term memories. He or she will test the subject's knowledge of both broad and specific information, such as the subject's ability to identify the current president of the United States. In addition to this, the medical professional may request that the patient recite a string of words.

Memory loss can be a significant problem and getting a memory evaluation can tell you how serious of a problem it is and what kind of assistance the person may need.

Diagnostic tests

  • Brain damage or abnormalities can be detected using imaging tests such as MRIs and CT scans.
  • Infection, deficiency, or other issues can be discovered through blood tests.
  • Checking for seizure activity with an electroencephalogram.

Treatment

There are many techniques and strategies that can be used to help compensate for memory loss, as well as to treat any other conditions that may be contributing to the amnesia.

Medications

The vast majority of amnestic conditions cannot currently be treated with any of the available pharmaceuticals.

Amnesia is a symptom of Wernicke-Korsakoff syndrome, which is caused by an insufficient amount of thiamin in the body. As part of the treatment, this vitamin needs to be taken, and the patient should be given the appropriate nutrition. Even with treatment that involves complete abstinence from alcohol, many patients' memories will never return. This is the case even when the patients are treated.

Memory disorders may one day see improvements as a result of the latest research. Because there are so many different brain processes at play, it is highly unlikely that a single medication will solve memory problems.4

Occupational therapy

Those who suffer from amnesia may find that working with an occupational therapist can assist them in constructing a foundation of intact memories, which will allow them to more effectively take in new information.

Memory training may also include the practise of a variety of methods for arranging information in a way that is both simpler to recall and more conducive to improved comprehension of lengthy conversations.

Technological assistance

People who are suffering from amnesia or have lost their memories may find that mobile devices such as smartphones and tablets are a godsend. Even people with severe amnesia have the potential to use electronic organizers successfully with just a little bit of training and practise. Smartphones, for instance, can be set to alert their owners of upcoming events or to remind them to take their medication at the appropriate time.

The use of notebooks, wall calendars, pill minders, and photographs of people and places are all examples of low-tech memory aids.

Other activities to improve the memory

It may be challenging to deal with the symptoms of amnesia for those who have the condition, as well as for their loved ones and other close friends and acquaintances. Those who suffer from more severe forms of amnesia might need direct assistance from family members, friends, or even paid caregivers.

If you suffer from amnesia, you might find it beneficial to discuss your experiences with people who have been in your shoes and can relate to what you're going through. If you or a loved one suffers from amnesia, you should inquire with your primary care physician about the existence of a local support group.

In the event that an underlying cause for amnesia is identified, there are national organisations that can offer the individual and their family’s supplementary information or support in the event that this is necessary. (800-272-3900) Association for Alzheimer's Disease (800-444-6443)

Is amnesia permanent?

Memory loss can last a long time, unlike a brief loss of memory (transient global amnesia).

Although amnesia can't be cured, it's possible to help those who suffer from it by improving their memory and providing emotional support.

Prevention

  1. Avoid getting extremely drunk or high, as well as using drugs.
  2. When participating in activities that put a player at a high risk of sustaining a concussion, they should always wear protective headgear.
  3. Be sure to fasten your seatbelt every time you get into a vehicle.
  4. Getting medical help as soon as possible is the best way to stop an infection from spreading to the brain.
  5. You should get your eyes checked once a year, and if you are over the age of 60, you should inquire about any prescribed medications that could cause dizziness. There is a possibility that this will aid in the prevention of falls.
  6. You should strive to keep your mental activity at a healthy level for the rest of your life. You have options such as going to school, travelling, improving your reading skills, and engaging in challenging gaming.
  7. Always make time for some form of physical activity in your day-to-day life!
  8. In order to maintain a healthy and robust heart, it is important to eat a diet that is abundant in fruits, vegetables, whole grains, and lean proteins. Amnesia and other memory loss conditions can be avoided by maintaining a healthy lifestyle, including eating well and getting regular exercise.
  9. Maintaining proper hydration is crucial.
  10. According to the findings of some studies, even mild dehydration can have a negative impact on brain function, particularly in women.

Complications

Even relatively mild cases of amnesia have been shown to have a detrimental effect on a person's quality of life. If you are unable to retrieve old memories or form new ones, you may find it challenging to carry out the activities required of you daily, both at work and in social settings.

It is not always possible to recover forgotten memories once they have been lost.

Those who are affected by severe amnesia might require care around the clock if their condition is severe enough.

Summary

Patients who are suffering from an organic brain disease (particularly schizophrenia), psychosis (particularly hysteria), or intentional memory loss are all at risk for amnesia or a loss of personal identification. Depending on the specifics of the case, isolating the causative agent of a disease, and determining its aetiology can be a straightforward or challenging endeavour. In addition to any accompanying signs and symptoms, the structure of the amnesic defect and the personality of the individual before they lost their memory may be helpful in diagnosing the condition. If the amnesic episode is used as a means of escaping a difficult personal situation or the consequences of that situation, then it is likely that the amnesic episode will be simulated at some point. Many patients experience a speedy and frequently unprompted recovery.

References

  1. Cubelli R, Della Sala S. Amnesia. Cortex 2021;136:158.
  2. Markowitsch HJ, Staniloiu A. Functional (dissociative) retrograde amnesia. Handb Clin Neurol 2016;139:419-445.
  3. Markowitsch HJ. Anterograde amnesia. Handb Clin Neurol 2008;88:155-183.
  4. Lennox WG. Amnesia, real and feigned. Am J Psychiatry 1943;99(5):732-743.
  5. NHS. Amnesia ( Memory Loss). 2020; Available at: https://www.nhs.uk/conditions/memory-loss-amnesia/. Accessed 23/05/, 2022.

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Muhammad Mohsin

Master's degree - MSc Medical Bioscience, Glasgow Caledonian University, Scotland
Muhammad is an Ex. Hospital Pharmacist at Aga Khan University Hospital.

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