Amnesia

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

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.


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.

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.

TREATMENT
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.