Amnesia

Definition

Amnesia refers to the loss of memories, such as facts, information and experiences. Though having no sense of who you are is a common plot device in movies and television, real-life amnesia generally doesn't cause a loss of self-identity.

Instead, people with amnesia — also called amnestic syndrome — are usually lucid and know who they are, but may have trouble learning new information and forming new memories.

Amnesia can be caused by damage to areas of the brain that are vital for memory processing. Unlike a temporary episode of memory loss (transient global amnesia), amnesia can be permanent.

There's no specific treatment for amnesia, but techniques for enhancing memory and psychological support can help people with amnesia and their families cope.

Symptoms

The two main features of amnesia are:

• Impaired ability to learn new information following the onset of amnesia (anterograde amnesia)
• Impaired ability to recall past events and previously familiar information (retrograde amnesia)

Most people with amnesia have problems with short-term memory — they can't retain new information. Recent memories are most likely to be lost, while more remote or deeply ingrained memories may be spared. Someone may recall experiences from childhood or know the names of past presidents, but not be able to name the current president or remember what month it is or what was for breakfast.

Isolated memory loss doesn't affect a person's intelligence, general knowledge, awareness, attention span, judgment, personality or identity. People with amnesia usually can understand written and spoken words and can learn skills such as bike riding or piano playing. They also may understand they have a memory disorder.

Amnesia isn't the same as dementia. Dementia often includes memory loss, but it also involves other significant cognitive problems that lead to a decline in the ability to carry out daily activities. A pattern of forgetfulness is also a common symptom of mild cognitive impairment (MCI), but the memory and other cognitive problems in MCI aren't as severe as those experienced in dementia.

Additional signs and symptoms
Depending on the cause of the amnesia, other signs and symptoms may include:

• False recollections (confabulation), either completely invented or made up of genuine memories misplaced in time
• Neurological problems such as uncoordinated movements, tremors or seizures
• Confusion or disorientation

When to see a doctor
Anyone who experiences unexplained memory loss, head injury, confusion or disorientation requires immediate medical attention. A person with amnesia may not be able to identify his or her location or have the presence of mind to seek medical care. If someone you know has symptoms of amnesia, help the person get medical attention.

Causes

Normal memory function involves many parts of the brain, and any disease or injury that affects the brain can interfere with the intricacies of memory. Amnesia can result from damage to brain structures that form the limbic system, which controls your emotions and memories. These structures include the thalamus, which lies deep within the center of your brain, and the hippocampal formations, which are situated within the temporal lobes of your brain.

Amnesia caused by brain injury or damage is known as neurological or organic amnesia. Possible causes of neurological amnesia include:

• Stroke
• Brain inflammation (encephalitis) resulting from infection with a virus such as herpes simplex virus or as an autoimmune reaction to cancer somewhere else in the body (paraneoplastic limbic encephalitis)
• Lack of adequate oxygen in the brain (for example, from heart attack, respiratory distress or carbon monoxide poisoning)
• Long-term alcohol abuse leading to thiamin (vitamin B-1) deficiency (Wernicke-Korsakoff syndrome)
• Tumors in areas of the brain that control memory
• Degenerative brain diseases, such as Alzheimer's disease and other forms of dementia
• Seizures
• Electroconvulsive therapy, a procedure in which electrical currents are passed through the brain, sometimes used to treat certain mental illnesses
• Certain medications, such as benzodiazepines

Head injuries, such as those sustained in car accidents, can lead to confusion and problems remembering new information, especially in the early stages of recovery — but usually don't cause severe amnesia.

Another rare type of amnesia, called psychogenic or dissociative amnesia, stems from emotional shock or trauma, such as being the victim of a violent crime. In this disorder, a person may lose personal memories and autobiographical information, usually only briefly.

Risk factors

The chance of developing amnesia might increase if you've experienced:

• Brain surgery, head injury or trauma
• Stroke
• Alcohol abuse
• Seizures

Complications

Amnesia varies in severity and scope, but even mild amnesia takes a toll on daily activities and quality of life. The syndrome can cause problems at work, at school and in social settings. It may not be possible to recover lost memories. Some people with severe memory problems need to live in a supervised situation or extended care facility.

Preparing for your appointment

You're likely to start by seeing your family doctor or a general practitioner. However, you may then be referred to a doctor who specializes in disorders of the brain and nervous system (neurologist).

It's a good idea to arrive at your appointment well prepared. Here's some information to help you get ready for your appointment and to know what to expect from your doctor.

What you can do

• Write down any unusual symptoms as you experience them, including any that may seem unrelated to the reason for which you scheduled the appointment.
• Write down key personal information, including any major stresses or recent life changes you can recall. Ask family members or friends to help you to ensure your list is complete.
• Make a list of all medications, vitamins or supplements you're taking.
• Ask a family member or friend to come with you. Even in the best circumstances, it can be difficult to remember all of the information provided to you during an appointment. Someone with you can help you remember everything that was said.
• Bring a notepad and pen or pencil to jot down the points you want to be sure to remember later.
• Write down questions to ask your doctor.

Preparing a list of questions can help you make the most of your time with your doctor, as well as ensure that you cover everything you want to ask. For amnesia, some basic questions to ask your doctor include:

• What's the most likely cause of my symptoms?
• Are there other possible causes for my symptoms?
• What kinds of tests do I need? Do these tests require any special preparation?
• Will my memory ever come back?
• What treatments are available, and which do you recommend?
• I have other health conditions. How can I best manage them together?
• Do I need to restrict any activities?
• Are there any brochures or other printed material that I can take home? What websites do you recommend?

In addition to the questions that you've prepared to ask your doctor, don't hesitate to ask questions during your appointment at any time that you don't understand something.

What to expect from your doctor
Your doctor is likely to ask you a number of questions, including:

• When did you first notice your memory loss?
• Did you experience any other symptoms at that time?
• Were you involved in any trauma? For example, a car accident, violent collision in sports or an assault?
• Did an illness or another event seem to trigger the memory loss?
• Does anything help improve your memory?
• What, if anything, appears to worsen your memory loss?
• Are the memory problems intermittent or constant?
• Has the memory loss stayed the same or is it getting worse?
• Did the memory loss come on suddenly or gradually?

Tests and diagnosis

To diagnose amnesia, a doctor will do a comprehensive evaluation to rule out other possible causes of memory loss, such as Alzheimer's disease, other forms of dementia, depression or brain tumor.

Medical history
The evaluation starts with a detailed medical history. Because the person with memory loss may not be able to provide thorough information, a family member, friend or another caregiver generally takes part in the interview as well.

The doctor will ask many questions to understand the memory loss. Issues that might be addressed include:

• Type of memory loss (can the person remember recent events and remote events?)
• When the memory problems started and how they progressed
• Triggering factors, such as head injury, stroke or surgery
• Family history, especially of neurological disease
• Drug and alcohol use
• Other signs and symptoms, such as confusion, language problems, personality changes or impaired ability to care for self
• History of seizures, headaches, depression or cancer

Physical exam
The physical examination may include a neurological exam to check reflexes, sensory function, balance, and other physiological aspects of the brain and nervous system.

Cognitive tests
The doctor will test the person's thinking, judgment, and recent and long-term memory. He or she will check the person's knowledge of general information — such as the name of the current president — as well as personal information and past events. The memory evaluation can help determine the extent of memory loss and provide insights about what kind of help the person may need.

Imaging tests
Diagnostic imaging tests — including MRI, CT scan and electroencephalogram — may be ordered to look for damage or abnormalities in the brain. Blood tests can check for infection, nutritional deficiencies or other issues.

Treatments and drugs

Treatment for amnesia focuses on techniques and strategies to help make up for the memory problem.

Occupational therapy
A person with amnesia may work with an occupational therapist to learn new information to replace what was lost, or to use intact memories as a basis for taking in new information. Memory training may also include a variety of strategies for organizing information so that it's easier to remember and for improving understanding of extended conversation.

Technological assistance
Many people with amnesia find it helpful to use a PDA, such as a Palm Treo, BlackBerry or iPhone. With some training and practice, even people with severe amnesia can use these electronic organizers to help with day-to-day tasks. For example, they can program the PDA to remind them about important events or to take medications.

Low-tech memory aids include notebooks, wall calendars, pill minders and photographs of people and places.

Medications or supplements
No medications are currently available for treating most types of amnesia. Because Wernicke-Korsakoff syndrome involves a lack of thiamin, treatment includes replacing this vitamin and providing proper nutrition. Although treatment, which also needs to include alcohol abstinence, can help prevent further damage, most people won't recover all of their lost memory.

Researchers are investigating several neurotransmitters involved in memory formation, which may one day lead to new treatments for memory disorders. But the complexity of the brain processes involved makes it unlikely that a single medication will be able to resolve memory problems.

Coping and support

Living with amnesia can be frustrating for the person with memory loss, and for family and friends too. More-severe forms of amnesia may require direct assistance for the affected person from family, friends or professional caregivers.

It can be helpful to talk with others who understand what you're going through, and who may be able to provide advice or tips on living with amnesia. Ask your doctor if he or she knows of a support group in your area for people with amnesia and their loved ones.

If an underlying cause for the amnesia is identified, there are national organizations that can provide additional information or support for the individual and their families. Examples include:

• The Alzheimer's Association (800-272-3900)
• The Brain Injury Association of America (800-444-6443)

Prevention

Because damage to the brain can be a root cause of amnesia, it's important to take steps to minimize your chance of a brain injury. For example:

• Avoid excessive alcohol use.
• Wear a helmet when bicycling and a seat belt when driving.
• Treat any infection quickly so that it doesn't have a chance to spread to the brain.
• Seek immediate medical treatment if you have any symptoms that suggest a stroke or brain aneurysm, such as a severe headache or one-sided numbness or paralysis.