Amnesia

Sometimes people forget things.

This can happen to the brain. It can happen from a head injury. It can also happen from a sickness.

Some people forget things from long ago. This is one way it works. Other people cannot make new memories. They might forget what they just did.

Even if they forget, they may still have skills. They might remember how to draw. They might remember how to play music.

People can still use their words and be social. They can still learn some new things. It is a hard thing to go through.

We can help people by being kind. We can help them stay on a routine.

Amnesia is when a person has trouble remembering things. It can be caused by brain damage or brain diseases. Some drugs can also cause it for a short time.

There are two main types. Retrograde amnesia is when you cannot remember things from the past. This might be from an accident. Some people lose months of memory. Others may lose many years.

Anterograde amnesia is when you cannot make new memories. It is hard to move new info into long-term storage. These two types can happen at the same time.

Damage to parts of the brain causes this. The hippocampus is a very important part. It helps the brain make new memories. Damage to the medial temporal lobe also causes memory loss.

Even with amnesia, some things stay the same. People often keep their social skills. They can still use words well. They can also keep "procedural memory." This is the memory for how to do skills. A person might remember how to play music or paint. They may even learn a new task without knowing how they learned it.

Amnesia is a way that memory can be lost or weakened. It happens when the brain has damage or certain diseases. Sometimes, people might also experience it temporarily from using specific drugs. This loss of memory can be a small part of a person's life or it can be very large.

The amount of memory lost usually depends on how much damage the brain has taken. It is a serious condition that affects how people hold onto their past and their present.

There are two main ways this memory loss works. The first way is called retrograde amnesia. This is when a person cannot remember things that happened before a certain date. This date might be the day of an accident or a surgery.

Sometimes this loss covers just a few months. Other times, it can reach back many decades. The second way is called anterograde amnesia. This makes it hard to move new information into long-term storage. People with this type cannot remember things for long periods of time.

Scientists have studied many different causes for these memory changes. Some people experience amnesia from head trauma or injuries to the brain. Others might face it due to traumatic events that cause deep emotional stress. This is called dissociative amnesia.

It happens when the mind chooses to forget something very upsetting. There are also physical deficiencies that can cause it. These include things like Alzheimer's disease or a lack of vitamin B12. Even certain medical treatments, like electroconvulsive therapy, can cause temporary memory loss.

Much of this happens because of specific parts of the brain. The hippocampus is a very important area for making new memories. If the CA1 region of the hippocampus is damaged, it is hard to form new episodic memories. Episodic memories are the ones about specific events in your life.

Damage to the medial temporal lobe also plays a big role. Scientists have even found that a lack of a protein called RbAp48 is linked to memory loss. In mice, lower levels of this protein were seen in those with damaged memory.

Even when someone has amnesia, many parts of their mind stay strong. They often keep their social skills and their ability to use language. They can also keep procedural memory. This is the memory for how to perform specific skills.

For example, a patient named LSJ could still read music and use art techniques. She even scored high in watercolor skills. This shows that the brain has different ways of storing different kinds of knowledge. People can learn new tasks even if they do not remember learning them.

Amnesia is a significant deficit in memory caused by brain damage or various brain diseases. It can also occur temporarily due to the use of certain sedative or hypnotic drugs. This condition affects how a person stores and retrieves information from their past and present. The extent of the memory loss can range from being a partial deficit to a total loss. This variation depends heavily on the specific nature and scale of the damage to the brain.

Understanding amnesia helps scientists learn how the brain organizes different types of knowledge.

There are two primary types of amnesia: retrograde and anterograde. Retrograde amnesia is the inability to recall information that was acquired before a specific date. This date is often the time of a medical operation or an accident. The loss can span only a few months or reach back many decades. Anterograde amnesia is the inability to transfer new information from short-term storage into long-term storage. People with this condition struggle to remember things for any significant length of time. These two types can also occur at the same time in a single person.

Researchers recognize several other distinct forms of memory impairment. Transient global amnesia is a temporary loss of memory that arrives suddenly. Dissociative amnesia is linked to intense emotional stress and involves an inability to recall personal experiences. Childhood amnesia refers to the common loss of early life memories seen across individuals. Post-traumatic amnesia can follow a head injury and involves confusion regarding events near the time of the trauma. Each of these forms represents a different way the brain's memory systems can fail.

Memory functions are tied to specific biological structures within the brain. Case studies show that amnesia is frequently associated with damage to the medial temporal lobe. Specific areas of the hippocampus, such as the CA1 region, are also vital for memory. Damage to the CA1 pyramidal cells can prevent the hippocampus from making connections to the cortex. This often results in a failure to form new episodic memories. Additionally, damage to the diencephalon can cause amnesia. Recent studies also show a correlation between a deficiency of the RbAp48 protein and memory loss. In mice, lower levels of this protein are found in those with damaged memory.

Scientists categorize the causes of amnesia into three general groups. The first group is head trauma, which includes any injury or active action toward the brain. The second group includes traumatic events, which are subjective and depend on what a person finds distressing. For example, dissociative amnesia can occur after a person witnesses a fatal car accident. The third group is physical deficiencies, which are more passive issues. These include Alzheimer's disease, vitamin B12 deficiency, or neurological syndromes like anti-NMDA receptor encephalitis. Other specific causes include alcohol use, strokes, and even the use of fentanyl.

Memory is not a single system, but is divided into declarative and non-declarative types. Declarative memory includes semantic memory, which is facts, and episodic memory, which is related to personal events. A patient named LSJ experienced retrograde declarative memory loss from medial temporal lobe damage. However, she could still remember how to perform specific declarative skills like reading music or art techniques. In contrast, non-declarative memory involves skills and implicit learning. This includes procedural memory, which is the memory for how to perform tasks. Patients can often learn new procedural knowledge even if they cannot consciously recall the learning event.

Even with profound impairments, many intellectual and social skills remain intact. Individuals with amnesia often retain their linguistic abilities and social skills. They may also benefit from perceptual priming, which is a form of non-declarative memory. In priming, a person has no conscious recall of an event but still shows a response to it. This was seen in patients who performed well on word fragment completion tasks. While anterograde amnesia cannot be treated with drugs due to neuronal loss, support is vital. Educating patients on daily routines can help utilize their intact procedural memory to improve their quality of life.