Amnesia refers to the loss of memories, such as facts, information and experiences. Though forgetting your identity is a common plot device in movies and television, that's not generally the case in real-life amnesia.
Instead, people with amnesia â also called amnestic syndrome â usually know who they are. But, they 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.
The two main features of amnesia are:
- Difficulty learning new information following the onset of amnesia (anterograde amnesia)
- Difficulty remembering past events and previously familiar information (retrograde amnesia)
Most people with amnesia have problems with short-term memory â 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, know what month it is or remember 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 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 daily functioning.
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 memories (confabulation), either completely invented or made up of genuine memories misplaced in time
- 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.
Normal memory function involves many parts of the brain. Any disease or injury that affects the brain can interfere with 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 amnesia. Possible causes of neurological amnesia include:
- Brain inflammation (encephalitis) as a result of an infection with a virus such as herpes simplex virus, as an autoimmune reaction to cancer somewhere else in the body (paraneoplastic limbic encephalitis), or as an autoimmune reaction in the absence of cancer
- Lack of adequate oxygen in the brain, for example, from a 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
- Certain medications, such as benzodiazepines or other medications that act as sedatives
Head injuries that cause a concussion, whether from a car accident or sports, can lead to confusion and problems remembering new information. This is especially common in the early stages of recovery. Mild head injuries typically do not cause lasting amnesia, but more-severe head injuries may cause permanent amnesia.
Another rare type of amnesia, called dissociative (psychogenic) 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, but usually only briefly.
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 a brain tumor.
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 â recent or long term
- When the memory problems started and how they progressed
- Triggering factors, such as a 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
The physical examination may include a neurological exam to check reflexes, sensory function, balance, and other physiological aspects of the brain and nervous system.
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 â such as the name of the current president â as well as personal information and past events. The doctor may also ask the person to repeat a list of words.
The memory evaluation can help determine the extent of memory loss and provide insights about what kind of help the person may need.
The doctor may order:
- Imaging tests â including an MRI and CT scan â to check for brain damage or abnormalities
- Blood tests to check for infection, nutritional deficiencies or other issues
- An electroencephalogram to check for the presence of seizure activity
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.
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.
Coping and support
Living with amnesia can be frustrating for those with memory loss, and for their family and friends, too. People with more-severe forms of amnesia may require direct assistance 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)
The chance of developing amnesia might increase if you've experienced:
- Brain surgery, head injury or trauma
- Alcohol abuse
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