Amnesia (patient information)
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Memory loss (amnesia) is unusual forgetfulness. It may refer to not being able to remember new events, not being able to recall one or more memories of the past, or both.
What are the causes?
There are many areas of the brain that help you create and retrieve memories. Damage or malfunction of any of these areas can lead to memory loss.
Memory loss due to problems with specific brain areas may be different. It may involve only memory of recent or new events, passed or remote events, or both. the amnesia may be only for specific events or for all events. The problem may involve learning new information or forming new memories.
Mental or thinking abilities may still be present or may have been lost. Filling in the details with imagined events (confabulation), and disorientation to time and place may occur.
Memory loss may be for words and thoughts only, or for motor memory (the body can no longer perform specific actions). Memory loss may also be partial, meaning failing to remember only a selected group of items.
Memory loss may be short-term (called transient).
Causes of memory loss include:
- Alcohol or ilicit drug intoxication
- An event in which not enough oxygen was going to the brain (heart stopped, stopped breathing, complications from receiving anesthesia)
- Brain growths (caused by tumors or infection)
- Brain infections such as Lyme disease, syphilis, or HIV/AIDS
- Brain surgery, such as surgery to treat seizure disorders
- Cancer treatments, such as brain radiation, bone marrow transplant, or after chemotherapy
- Certain medications
- Certain types of seizures
- Depression, bipolar disorder, or schizophrenia when symptoms have not been well controlled
- Dissociative disorder (not being able to remember a major, traumatic event; the memory loss may be short-term or long-term)
- Drugs such as barbiturates or benzodiazepines
- Electroconvulsive therapy (especially if it is long-term)
- Encephalitis of any type (infection, autoimmune disease, chemical/drug induced)
- Epilepsy that is not well controlled with medications
- Head trauma or injury
- Heart bypass surgery
- Illness that results in the loss of, or damage to nerve cells (neurodegenerative illness), such as Parkinson's disease, Huntington's disease, or multiple sclerosis
- Long-term alcohol abuse
- Migraine headache
- Mild head injury or concussion
- Nutritional problems (vitamin deficiencies such as low vitamin B12)
- Permanent damage or injuries to the brain
- Transient global amnesia
- Transient ischemic attack (TIA)
Who is at highest risk?
The cause determines whether amnesia comes on slowly or suddenly, and whether it is temporary or permanent. Normal aging may lead to trouble learning new material or requiring a longer time to remember learned material. However, it does not lead to dramatic memory loss unless diseases are involved. Memory loss can be seen with impaired concentration, such as with depression. It can be hard to tell the difference.
The doctor will perform a thorough examination and take a medical history. This will almost always include asking questions of family members and friends. They should come to the appointment.
Medical history questions may include:
- Can the person remember recent events (is there impaired short-term memory)?
- Can the person remember events from further in the past (is there impaired long-term memory)?
- Is there a loss of memory about events that occurred before a specific experience (anterograde amnesia)?
- Is there a loss of memory about events that occurred soon after a specific experience (retrograde amnesia)?
- Is there only a minimal loss of memory?
- Does the person make up stories to cover gaps in memory (confabulation)?
- Is the person suffering from low moods that impair concentration?
- Time pattern
- Has the memory loss been getting worse over years?
- Has the memory loss been developing over weeks or months?
- Is the memory loss present all the time or are there distinct episodes of amnesia?
- If there are amnesia episodes, how long do they last?
- Aggravating or triggering factors
- Has there been a head injury in the recent past?
- Has the person experienced an event that was emotionally traumatic?
- Has there been a surgery or procedure requiring general anesthesia?
- Does the person use alcohol? How much?
- Does the person use illegal/illicit drugs? How much? What type?
- Other symptoms
- What other symptoms does the person have?
- Is the person confused or disoriented?
- Can they independently eat, dress, and perform similar self-care activities?
- Have they had seizures?
The physical examination will include a detailed test of thinking and memory (mental status or neurocognitive test), and an examination of the nervous system. Recent, intermediate, and long-term memory will be tested.
Diagnostic tests that may be performed include the following:
- Blood tests for specific diseases that are suspected (such as low vitamin B12 or thyroid disease)
- Cerebral angiography
- Cognitive tests (psychometric tests)
- CT scan or MRI of the head
- Lumbar puncture
When to seek urgent medical care?
Call your health care provider if you have any unexplained memory loss.
Cognitive therapy, usually through a speech/language therapist, may be helpful for mild to moderate memory loss.
The family should provide support. Reality orientation is recommended- supply familiar music, objects, or photos, to help the person stay oriented. Some people may need support to help them relearn. Any medication schedules should be written down so the person does not have to rely on memory. Extended care facilities, such as nursing homes, should be considered for people whose basic needs cannot be met in any other way, or whose safety or nutrition is in jeopardy.