Amnesia

Overview

Amnesia, also called amnestic syndrome, refers to the loss of memories, including facts, information and experiences. Movies and television tend to show people with amnesia forgetting who they are. But that's not generally the case in real life.

Instead, people with amnesia typically 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 if an underlying cause of amnesia is found, treatment often can be directed at that condition. Using strategies to enhance memory and getting 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 information that used to be familiar.

Most people with amnesia have issues with short-term memory, so they can't remember new information. Recent memories are most likely to be lost. But people with amnesia may remember older or deeply ingrained memories.

For example, people with amnesia 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.

Memory loss alone 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 typically can understand written and spoken words. And they can learn skills such as bike riding or piano playing. They may understand that they have a condition that affects memory.

Amnesia isn't the same as dementia. Dementia often includes memory loss. But dementia also involves other changes in thinking that lead to a decline in daily functioning. These changes include having trouble with language, judgment, and visual and spatial skills.

Memory loss also is a common symptom of mild cognitive impairment. This condition involves memory loss and other cognitive issues that aren't as serious 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 has unexplained memory loss, a head injury or confusion needs medical attention right away.

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 that 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. Those brain structures 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 brain 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 without cancer in the body.
• Not enough oxygen in the brain. This may happen as a result of a heart attack, breathing trouble or carbon monoxide poisoning.
• Long-term alcohol misuse that leads to too little vitamin B-1, known as thiamin, in the body. This condition is called Wernicke-Korsakoff syndrome.
• Tumors in areas of the brain that control memory.
• Alzheimer's disease and related diseases that involve the loss of brain cells that are important for memory.
• Seizures.
• Medicine such as benzodiazepines and other medicines that act as sedatives.

Head injuries that cause a concussion can lead to confusion. They also can make it hard to remember new information. This is especially common in the early stages of recovery after a concussion. Mild head injuries typically don't cause lasting amnesia. But head injuries that are more serious may cause permanent amnesia.

Another rare type of amnesia, called dissociative amnesia, comes from emotional shock or trauma. It can result from being the victim of a violent crime or experiencing other trauma. In dissociative amnesia, people may lose personal memories and information about their lives. This type of amnesia typically doesn't last long.

Risk factors

The following conditions can raise the risk of developing amnesia:

• Brain surgery, head injury or head trauma.
• Stroke.
• Alcohol use disorder.
• Seizures.

Complications

How much amnesia affects memory is different from person to person. But even mild amnesia takes a toll on daily activities and quality of life. Amnesia can make it hard to function at work, at school and in social settings.

It may not be possible to recover lost memories. Some people with serious memory loss 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 medical treatment right away if you have symptoms that suggest a stroke or brain aneurysm, including:
• A serious headache.
• Feeling numb on one side of the body.
• Not being able to move one side of the body.