What is amnesia?

Amnesia refers to partial or complete memory loss. Becoming forgetful is common and normal as a person ages, however, when memory loss begins to interfere with activities of daily living, it needs to be assessed by a physician to be a sign of a deeper illness.

When is amnesia present?

Memory loss or amnesia is said to be present when a person loses the ability to remember events and information that they would regularly or normally remember.

Memory loss may deal with things heard or seen within a few minutes or seconds or something that has occurred in the past.

Amnesia may begin suddenly or may follow a longer course as it worsens over time, for example over a year or so. It is most often a temporary condition. (1-4)

Amnesia can be severely distressing for the patient as well as for his or her family and friends. If amnesia is found to interfere with activities of daily living it should be analysed.

Types of memory loss

Types of memory loss may include –

  • Losing immediate memory such as forgetting sights or sounds which are only stored for a few seconds.
  • Recent memory loss or short term memory loss – This includes loss of chunks of memories like telephone numbers or other numbers and codes that are stored temporarily.
  • Long term or remote memory loss – This involves losing more permanent memories from the past. This is usually sign of a deeper memory impairment rather than amnesia.

Range of memory loss

Memory loss may range from mild forgetfulness to more severe and permanent cases of dementia. Around 40% of people aged over 65 have some kind of memory problem, and only 15% will develop dementia each year.

Other emotional problems associated with amnesia

Amnesia is often accompanied by other emotional problems like anxiety, depression and stress.

Here memory loss is more due to poor concentration rather than actual memory impairment. In addition these patients also have difficulty sleeping that affects memory.

Amnesia after a head injury

Amnesia may also occur after a head injury or after a stroke. This type of amnesia is sudden and patient often forgets all that has happened before the incident (accident causing head injury or the stroke). This is called retrograde amnesia.

If the patient forgets everything that happened after the trauma, it is called anterograde amnesia.

Other causes of memory loss

Other causes of memory loss include:

  • disease of the thyroids,
  • as side effects of some medications such as sedatives or drugs used in Parkinson’s disease,
  • long term alcohol abuse
  • vitamin B1 (thiamine) deficiency (causing Korsakoff’s psychosis),
  • brain infections (Lyme’s disease, syphilis or HIV/AIDS)
  • a sudden stressful or traumatic event leading a person to block an unpleasant memory (psychogenic amnesia)

Amnesia may also occur in brain tumors.

Childhood amnesia refers to a person's inability to recall events from early childhood.

Transient global amnesia

Transient global amnesia is related to psychological trauma or a medical procedure. It leads to repetitive questioning and sometimes confusion.

It lasts for 4-12 hours with a full recovery. This is termed fugue amnesia if there is loss of personal identity due to severe psychological trauma.

Usually, the memory comes back slowly or suddenly a few days later.

Prevention of amnesia

Amnesia patients need adequate support from friends and family. Memory loss may be prevented by adopting a healthier lifestyle and keeping brain’s memory function active with aging.

Edited by April Cashin-Garbutt, BA Hons (Cantab)

Causes of amnesia

Amnesia is a form of memory loss that is usually temporary and affecting short term memory.

Common causes and risk factors of amnesia and memory loss include concomitant psychological problems, trauma or head injury and so forth. (1-6)

Concomitant psychological problems

Many patients with memory loss present with other emotional problems like depression, stress and anxiety.

In these patients memory loss is due to poor concentration and not noticing things rather than actual memory impairment.

Sleeping problems are also reasons for poor memory in these patients.

Trauma, head injury, epileptic seizure or stroke

These may lead to sudden memory loss or amnesia.

In stroke, some of the blood supply to a part of the brain is cut off. This causes the brain tissues to die.

If the patient forgets everything that happened before the incident it is called retrograde amnesia and if he or she forgets all that happened after the incident, it is called anterograde amnesia.

This type of acute or sudden amnesia is caused due to lack of adequate oxygen in certain parts of the brain.

Other causes of amnesia

Other causes of amnesia include:

  • Thyroid problems – those with lower activities of the thyroid gland are at risk of memory loss
  • Sedatives and some medications used against Parkinson’s disease may cause memory loss over time.
  • Long term damage to the brain due to alcohol abuse. Korsakoff's psychosis is caused by long term alcohol abuse.
  • Dietary or other deficiency of the vitamin B1 or thiamine may lead to amnesia.
  • Transient global amnesia caused by problems with blood flow to part of the brain, which cause sudden episodes of memory loss that a person cannot remember afterwards.
  • Psychogenic amnesia where the patient blocks out a part of his or her memory of an unpleasant event in the past. This makes them unable to remember important information.
  • Infantile or childhood amnesia – Inability to remember events from early childhood. This may be due to psychological stress during that period of life.
  • Tumors of the brain may lead to amnesia
  • Brain infections like Lyme’s disease, syphilis or HIV/AIDS may lead to memory loss
  • After certain types of brain surgery.
  • After cancer chemotherapy, brain radiation or bone marrow transplant
  • After Electroconvulsive therapy especially over long term.
  • Slow decline of memory as seen in dementia caused by Alzheimer’s disease
  • Memory loss may be seen in poorly controlled cases of bipolar disorder, or schizophrenia.
  • Hormonal changes are responsible for memory loss. For example risk of memory loss rises with lower levels of estrogen in women after menopause. Elderly with high levels of corticosteroid are at risk of memory decline.
  • General physical illness may affect concentration and memory.

Edited by April Cashin-Garbutt, BA Hons (Cantab)

Symptoms of amnesia

Memory loss may range from mild forgetfulness to more sever and permanent dementias.

It is normal to be mildly forgetful with age. However, some worrying symptoms should alert the patient as well as the family and relatives as to the underlying causes of memory loss.

Questions asked to sufferers of amnesia

Some of the questions asked the sufferer to self or by family before deciding on consulting a physician include (1-2):

  • Is the memory impairment disrupting daily living activities? For example, memory loss affecting driving capabilities, maintaining personal hygiene etc.
  • Frequency of lapses in memory. Forgetting an appointment or event once in a while is normal but forgetting it repeatedly might mean a more severe memory lapse.
  • Types of things that are being forgotten. For example, forgetting the name of a new acquaintance is normal but a long term acquaintance is not.
  • If there is significant confusion. This may mean serious lapses in memory for example putting something in an inappropriate place. For example, a sufferer may place his shoes in the refrigerator.
  • If the memory loss is progressively becoming worse. If the memory loss worries friends or family.
  • Other features like repeating same phrases, questions, or stories in the same conversation or forgetting how to do routine tasks like combing hair, brushing teeth etc. There may be trouble making decisions or handling money and frequent episodes of getting lost in familiar places.

Specific symptoms of amnesia

Specific symptoms of memory loss and specifically amnesia include (3-5):

  • Loss of explicit memory or recent memory - The typical amnesic patient is unable to recall recent information like what they ate for lunch or a newly heard telephone number etc.

    These are called explicit memory as they are memories for facts and events that are capable of being consciously remembered. Patient or sufferer of loss of explicit memory can often declare the loss as this is in his or her knowledge.

  • Loss of implicit memory – Implicit memory refers to retention of the event or material information but incapability to recall it through conscious effort. In many cases the patient does not even have the knowledge that he or she has this information.
  • Normal or near-normal ability to learn new skills in amnesia patients. Patients have good learning ability (e.g. making a circle using a compass) which implies good implicit memory but they do not remember ever having practised the skill which implies poor explicit memory.
  • Anterograde amnesia – this means the patient forgets all events that have happened after a particular traumatic event. This is seen in acute or sudden onset amnesia like after a head injury, stroke or seizure.

    These patients do not tend to forget their childhood, events and skills prior to the accident. They however have trouble remembering day-to-day events.

  • Retrograde amnesia refers to an inability to remember information that was acquired before the traumatic event or disease. Typically there is very poor recall of events that occurred in the near past of the brain damage.
  • In Korsakoff’s psychosis memory loss is caused by alcohol abuse. The person's short-term memory may appear normal, however, if given a string of words or pictures or a simple story to remember, the patient falters.

    This is called “Confabulation” in which the sufferers make up stories to fill the gaps in their memory. There are other features like loss of feeling in the fingers and toes. This type of amnesia may remain even after five years of abstinence from alcohol

  • Childhood amnesia – This means inability to recall events from early childhood.
  • Transient global amnesia – This manifests as repetitive questioning, confusion about one’s own identity etc. It lasts for 4-12 hours with a full recovery.

    Loss of one’s own identity is termed fugue amnesia and is due to severe psychological trauma. Memory usually returns gradually.

Edited by April Cashin-Garbutt, BA Hons (Cantab)

Diagnosis of amnesia

Amnesia or memory loss can be transient or short term and may have a sudden or gradual onset and worsening.

With age most people tend to lose memory. However, when memory loss tends to interfere with activities of daily living, a more careful evaluation is warranted.

In many of these pathological cases forgetfulness becomes frequent and consistent and becomes cause for concern.

Assessment of amnesia

Assessment and diagnosis of amnesia and its cause involve (1-4):

  • Detailed look at medical and mental health history of the patient. Many patients presenting with memory loss suffer from other conditions like stress, anxiety and depression.
  • A detailed family history of memory related conditions like Alzheimer’s disease etc. is enquired.
  • Questions are asked regarding frequency of memory lapses, types of things forgotten, repetition of same phrases or questions in the same conversation, forgetting routine tasks—like brushing, bathing etc.

    Patients are assessed for confusion, trouble in decision making, judgement and handling money.

    Anterograde amnesia or loss of memory about events that occurred before a specific experience or retrograde amnesia or loss of memory about events that occurred soon after a specific experience is differentiated and detected. It is seen if memory loss is short term or long term.

  • History of triggering factors is enquired. This includes history of head injury in the recent past, an emotionally traumatic event in the recent past, recent requirement of a surgery under general anaesthesia, history of illicit drug or alcohol abuse.
  • A detailed physical examination is performed next to assess for different causes of amnesia.

    For example, in Korsakoff’s psychosis that occurs due to long term alcohol abuse also leads to numbness and loss of sensation in the fingers and toes.

    There is also a symptom of confabulation in Korsakoff’s psychosis when patient fills up gaps in his memory by making up information on his or her own.

Tests for amnesia

Tests for amnesia include blood tests, brain scans and so forth.

Blood tests for amnesia

Blood tests include:

  • Tests for low thyroid function. This is done by assessment of thyroid hormone.
  • Low vitamin B12 may also be detected by blood tests.
  • Routine blood tests assessing total blood count, liver and kidney functions are often prescribed for diagnosis of cause of memory loss

Brain scans for amnesia

A CT scan or MRI of the brain is often prescribed. This is done to detect a stroke, bleeding inside the brain or head injury that may have led to amnesia.

Other tests for amnesia

Other tests for amnesia include Cerebral angiography, EEG and so forth.

  • A Cerebral angiography may be prescribed.

    This test includes injection of a special dye via a vein in the arm. This travels to the blood vessels of the brain and the image is recorded. This gives a idea regarding a brain bleeding or stroke that may have led to the memory loss.

    Other imaging studies include magnetoencephalography and PET scan.

  • EEG or electroencephalogram is prescribed to detect abnormal electric activities in the brain. These are often diagnostic of epilepsy.
  • An infection or other brain pathology may be detected using assessment of the Cerebrospinal fluid by lumbar puncture.
  • Most important method of diagnosis includes psychometric tests or cognitive tests.

    There are numerous tools that are used to diagnose amnesia. These involve series or questionnaires and verbal, audiovisual or visual tests to detect the extent of memory loss.

    The most used tool is the Mini Mental State Examination (MMSE). It is most commonly used to diagnose memory loss.

    Another test is the Six Item Cognitive Impairment Test (6CIT) or the Kingshill test.

    For memory loss related to aging especially in the hospital settings commonly used test is the Abbreviated Mental Test (AMT).

Edited by April Cashin-Garbutt, BA Hons (Cantab)

Treatment of amnesia

Amnesia or memory loss is associated with stress, anxiety and frustration and is often very distressing for the patient as well as for his or her family and friends.

Types of treatment for amnesia

Treatment of amnesia and memory loss include (1-4):

  • Cognitive therapy using speech or language therapist can be of help in patients with mild to moderate memory loss.
  • In many cases mild memory loss may persist. Treatment of underlying medical conditions leading to memory loss.

    This includes treating low thyroid function, liver and kidney disease. Treatment of stroke, head injury, blood clots in brain and bleeding within the brain may be used to reduce memory loss due to these causes.

  • Treatment of concomitant psychiatric illness. This includes treating depression, anxiety, bipolar disorder and schizophrenia.
  • Treating alcoholism and preventing alcohol and illicit drug abuse.

Home care for amnesia

For management of amnesia home care is essential. Basic tenets of home care and prevention of complications include (5):

  • Prevention of falls – Often the elderly suffer from memory loss. This population is also prone to falls. A Fall Detector is part of an emergency call system that are worn on the belt and are sensitive to position. It can detect falls. Good lighting and avoidance of clutter helps prevent falls.
  • Doors should be left open and many houses have a provision to keep dangerous materials locked up and make sure the person cannot lock themselves in a room. Rooms can be labelled to prevent patients getting lost.
  • To prevent patients getting lost wanderer’s alarms and tags and transmitters may help. Patient is required to carry some form of identification with their name and address or contact number.
  • To prevent getting scalded by hot water it is necessary to install hot water shut-down and thermostats. There should be safety taps or tap covers to prevent risk of accidents.
  • Common concern in the kitchen is leaving the stove left on. A stove cut off may be used to cut off gas or power after a specified time. There should be a smoke alarm.
  • To remind patients to take medications there are medication organisers and pill reminders. The organizers have compartments for regular doses of medication. There are also electric pill reminders that have an alarm to remind individuals to take their tablets.
  • All important numbers, such as family and emergency, should be near the telephone. To keep the person oriented to time and place clocks with large numbers and calendars with large print may help reduce anxiety and frustration.

Prevention of amnesia

Prevention of amnesia (4, 6):

  • Memory loss may be prevented by healthy living and reduction of risk factors for heart disease, diabetes etc. This includes lowering cholesterol and high blood pressure. This also reduces risk of stroke and Alzheimer’s disease.
  • Excessive alcohol consumption, smoking, use of illicit drugs etc. should be avoided.
  • There is no evidence that certain herbs like gingko biloba prevents memory loss.
  • Regular physical activity helps maintain blood flow to the brain and reduces risk factors of memory loss.
  • Healthy and balanced diet is important in reducing risk of memory loss. Green leafy vegetables reduce the risk of decline of memory with age.
  • Good social relationships and interactions can help reduce risk of memory loss.
  • Brain activity should be maintained. This can be regular reading, writing, learning a new skill, or instrument, doing crossword or puzzles etc. stimulates brain cells and lower risk of memory loss.

Edited by April Cashin-Garbutt, BA Hons (Cantab)