An In-Depth Understanding Of Amnesia

Amnesia in simple terms is memory loss and has many types with various causes ⁽¹⁾. There are some types of amnesia which are temporary and some that can be permanent.

Individuals suffering from amnesia have problems in forming new memories; whereas some have difficulty in recalling past experiences, incidents or facts. Individuals suffering from amnesia often retain knowledge of who they are along with their motor skills.

Having some memory loss is a normal part of the aging process ⁽²⁾. However, if there is significant loss of memory or loss of ability to form new memories, then it can indicate that there is some form of amnestic disorder.

What are the Causes of Amnesia?

There are different causes of amnesia and consist of ⁽¹⁾:

Dementia: The site where the memory is stored in the brain depends on the age of the memory. When a person starts to lose very old memories, it can be an indication of extensive deterioration of the brain and this can be caused by any form of dementia including Alzheimer’s disease. People suffering from dementia tend to lose the latest memories first and often retain older memories for longer period of time.

Anoxia: When there is reduction in the oxygen levels to the brain, then it effects the entire functioning of the brain and can cause loss of memory. This condition is known as anoxia. If the anoxia is mild, then the memory loss may be temporary.

Damage to the Hippocampus: The area of the brain and limbic system, which is responsible for memory, is hippocampus. The function of the hippocampus is memory formation, organization of memories and retrieving and recalling them when needed. The hippocampus cells are the brain’s most fragile and energy-hungry cells and get easily disrupted or destroyed by anoxia and other dangers like toxins. When there is damage to the hippocampus then the person will have difficulty in forming new memories. If the damage occurs in both halves of the brain, then the patient will suffer from complete anterograde amnesia.

Head Injuries: Traumatic injuries to the head, such as tumors, stroke infections can also cause brain damage, which can include permanent memory issues. Concussions tend to disrupt the memories of the hours, days or weeks just before and after the injury has occurred.

Stress or Trauma: Acute stress or trauma can lead to dissociative amnesia where the mind can reject feelings, thoughts or information which the patient feels ill equipped to handle. Dissociative fugue is a specific type of dissociative amnesia, which can cause unexpected wandering and can also cause amnesia surrounding the circumstances of traveling and forgetting other details of life.

Alcohol Use: The use of alcohol for even a little time can cause blackout and this is a form of anterograde amnesia, which is temporary. Long-term alcohol use disorder can cause a brain disorder known as Wernicke-Korsakoff syndrome, which can lead to progressive memory loss from insufficient vitamin B1. A person having this condition will have problems with forming new memories; however, may not be aware of it.

Electroconvulsive Therapy (ECT): Electroconvulsive therapy (ECT) as a treatment for any mental health disorders can cause one to develop retrograde amnesia (3). One can also have anterograde amnesia that often resolves within 4 weeks of the treatment ⁽⁴⁾.

What are the Risk Factors for Amnesia?

The risk factors for amnesia are:

• Risk factors for cardiovascular disease, such as hypertension and high cholesterol.
• Having a history of migraine attacks.
• Emotional stress.
• Brain surgery or injury.

What are the Symptoms of Amnesia?

Memory loss or loss of ability to form new memories is the primary symptom of amnesia. A person suffering from amnesia can experience the following ⁽⁵⁾:

• Experiencing confusion.
• Difficulty in recalling places, events, facts or specific details.
• Not being able to recognize known faces or locations.
• Having confabulation where the brain subconsciously invents or fabricates false memories to fill in the gaps in memory.
• The motor skills remain intact including the ability to walk along with fluency in whatever language that the patient speaks.

What are the Types of Amnesia?

There are different types of amnesia and consist of ^{(6, 7)}:

Retrograde Amnesia: Someone having retrograde amnesia will lose previously made and existing memories. This form of amnesia first affects the recently formed memories. Older memories, which are from childhood, are often slowly affected. Dementia causes slow or gradual retrograde amnesia.

Anterograde Amnesia: Someone having anterograde amnesia is not able to form new memories and this can be temporary also. One can have anterograde amnesia after excessive alcohol consumption and experiencing a blackout that follows.

Anterograde amnesia can be permanent too if there is damage to the hippocampus in the brain. The role of hippocampus is important in forming new memories.

Transient Global Amnesia (TGA): Transient global amnesia (TGA) is not clearly understood and anybody who experiences it will suffer from agitation or confusion that comes and goes on repeat over a period of several hours. There can be memory loss in the hours before the attack without any lasting memory of the episode. According to experts Transient Global Amnesia occurs because of temporary blockage in the blood vessels supplying the brain or due to any seizure-like activity. This condition is more frequent in middle-aged individuals and older adults.

Dissociative Amnesia: In this type of amnesia the patient has difficulty in remembering vital information about themselves like name, family members, personal history and friends. Any traumatic or stressful event can cause dissociative amnesia and it often occurs abruptly and can persist for minutes, hours or days. Rarely can it last for months or years.

Childhood or Infantile Amnesia: There are many of us who cannot remember the initial 3 to 5 years of our life and this is known as infantile or childhood amnesia.

Drug-Induced Amnesia: This type of amnesia will occur after taking certain drugs. Some of the drugs which can cause this form of memory loss are: benzodiazepines, zopiclone, zolpidem, pentobarbital sodium, ketamine and flunitrazepam. Drug-induced memory loss is often temporary and can be seen in older adults who take different sorts of medications.

Post-Traumatic Amnesia (PTA): This form of amnesia is experienced by people who are hospitalized for a traumatic brain injury. Post-traumatic amnesia can also occur after a brief period of loss of consciousness. Patient can be awake, but will speak and behave in a weird manner, which is not like the patient. There can be inability to remember or recall events that have occurred from just mere minutes or hours ago. The duration of time which post-traumatic amnesia lasts can be an indication of the severity of the brain injury and it can last for less than 1 hour in case of mild trauma to more than 24 hours in case of acute brain injury.

What are the Complications of Amnesia?

Patients suffering from mild amnesia can also experience a reduced quality of life and it can prove to be challenging to do simple daily tasks of living and engaging in social activities because of difficulty in recalling previous memories and creating new ones. Sometimes, the lost memories cannot be recovered.

Patients with acute amnesia can require 24 hours of supervision.

How is Amnesia Diagnosed?

Diagnosis of amnesia is done by a neurologist and it is done by asking patient’s medical history and questions about memory loss and additional symptoms, which the patient is having. The doctor asks the caregiver or the family member answers to all these questions as the patient may not recall or be able to answer the questions.

Tests done for diagnosis of amnesia:

Cognitive tests are done to check the patient’s memory and other diagnostic tests, such as CT scan or MRI scan can be done to look for brain damage.

Blood tests are also done to look for nutritional deficiencies that can affect the cognitive function like insufficient levels of vitamin B12, vitamin B1or vitamin D.

Blood tests are also done to look for any infections, which can cause memory loss, such as syphilis, HIV or Lyme disease.

What is the Treatment for Amnesia?

Treatment of amnesia is done by understanding and treating the underlying cause of amnesia.

Resolves on its own: Amnesia caused by mild head trauma can resolve without treatment within minutes to hours ⁽⁸⁾. Amnesia caused from acute head injury can persist for a week. Rarely amnesia caused by acute head injury can last for many months.

Detoxification: Chemically induced amnesia, such as from alcohol, is resolved via detoxification. Once the abusive drug is expelled from system, the memory problems will gradually subside ⁽⁹⁾.

Medications: There is no definite cure for amnesia caused by dementia ⁽¹⁰⁾. However, there are medications, which help with learning and memory, such as galantamine, donepezil and or rivastigmine ⁽¹¹⁾.

Occupational therapy can be recommended when there is persistent memory loss. It can help in learning new memory skills and information, which will help with the daily living. The therapist also teaches how to use different techniques and memory aids for organizing information so it makes it easier to retrieve them.

Is there any way to Prevent Amnesia?

Some of the healthy habits to adopt to reduce the risk of head injuries, blackouts, stroke, dementia and other such causes for loss of memory are:

• Avoid heavy use of drugs or alcohol.
• Always wear a seatbelt when driving or traveling by car ⁽¹³⁾.
• Always wear protective headgear when playing sports, which increases the risk of concussion.
• Get annual eye checkups after crossing the age of 30 and ask your doctor about any medication, which can cause dizziness as a side effect to prevent falls.
• Always strive to be mentally active throughout your life. This can be done by reading books, solving puzzles, taking classes, exploring new places and playing mentally challenging games.
• It also important to stay physically active as long as you live.
• Drinks lot of water as it is important to stay hydrated. According to studies, even mild dehydration can affect brain functioning, more so in women ⁽¹⁴⁾.
• Treat infections immediately to prevent them from spreading to the brain.
• It is important to consume a heart-healthy diet, which includes lot of vegetables, fruits, low-fat proteins and whole grains. Doing so helps in preventing strokes and cardiovascular problems, which can lead to amnesia ⁽¹⁵⁾. A good diet also provides your brain with healthy nutrients for optimal brain health.

Conclusion

In some cases, amnesia can be permanent, but most of the times, it often resolves on its own. It is extremely challenging to live with amnesia and perform daily activities of living and a lot of outside help is needed. However, following healthy lifestyle and adopting healthier habits helps in cutting down the risk of amnesia.

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Also Read:

• What is Gluteal Amnesia & How Can It Be Treated?
• What is Anterograde Amnesia: Causes, Symptoms, Treatment, Risk Factors