Amnesia

Overview

Amnesia refers to the loss of memories, including facts, information and experiences. Movies and television tend to depict amnesia as forgetting your identity, but that's not generally the case in real life.

Instead, people with amnesia — also called amnestic syndrome — 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, called transient global amnesia, amnesia can be permanent.

There's no specific treatment for amnesia, but treatment can be directed at the underlying cause. Tips to help enhance memory and get support can help people with amnesia and their families cope.

Symptoms

The two main features of amnesia are:

• Trouble learning new information.
• Trouble remembering past events and previously familiar information.

Most people with amnesia have problems with short-term memory, so they can't retain new information. Recent memories are most likely to be lost. More-remote or deeply ingrained memories may be spared.

For example, people may recall experiences from childhood or know the names of past presidents. But they may not be able to name the current president, know the month or remember what they ate for breakfast.

Isolated memory loss doesn't affect a person's intelligence, general knowledge, awareness or attention span. It also doesn't affect 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 also involves other problems with thinking that lead to a decline in daily functioning. These problems include having trouble with language, judgment and visual-spatial skills.

Memory loss also is a common symptom of mild cognitive impairment. This disorder involves memory and other cognitive problems that aren't as severe as those experienced in dementia.

Additional symptoms

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

• False memories that are either completely invented or are real memories misplaced in time.
• Confusion or disorientation.

When to see a doctor

Anyone who experiences unexplained memory loss, head injury or confusion requires immediate medical attention.

People with amnesia may not know where they are or be able to seek medical care. If someone you know has symptoms of amnesia, help the person get medical attention.

Causes

Typical memory function involves many parts of the brain. Any disease or injury that affects the brain can affect memory.

Amnesia can result from damage to brain structures that form the limbic system, which controls emotions and memories. They include the thalamus found deep within the center of the brain. They also include the hippocampal formations found within the temporal lobes of the brain.

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

• Stroke.
• Brain inflammation, which may be due to an infection with a virus such as herpes simplex virus. Or inflammation may be a result of an autoimmune reaction to cancer somewhere in the body. It also may be due to an autoimmune reaction in the absence of cancer.
• Not enough oxygen in the brain. This may happen as a result of a heart attack, respiratory distress or carbon monoxide poisoning.
• Long-term alcohol misuse that leads to too little vitamin B-1, known as thiamin, in the body. When this happens, it's called Wernicke-Korsakoff syndrome.
• Tumors in areas of the brain that control memory.
• Alzheimer's disease and other diseases that involve the degeneration of nerve tissue.
• Seizures.
• Certain medicines such as benzodiazepines or others 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 don't cause lasting amnesia, but more-severe head injuries may cause permanent amnesia.

Another rare type of amnesia, called dissociative amnesia, stems from emotional shock or trauma. It can result from being the victim of a violent crime or experiencing other trauma. In this disorder, people may lose personal memories and information about their lives. The memory loss is usually brief.

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 be supervised or need to live in a care facility.

Prevention

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:

• Don't drink large amounts of alcohol.
• Wear a helmet when bicycling and a seat belt when driving.
• Treat infections quickly so that they don't have a chance to spread to the brain.
• Get immediate medical treatment if you have symptoms that suggest a stroke or brain aneurysm. Those symptoms include a severe headache, feeling numb on one side of the body or not being able to move one side of the body.