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.