Amnesia

The general term ‘amnesia’ refers to a large-scale loss of memory that could be caused by a brain injury, disease or some form of psychological trauma. There are two main forms of amnesia, which are

• Retrograde
• Anterograde

The type of amnesia that a person experiences, will depend on the part of the brain that has been affected, as different areas of the brain are responsible for short- and long-term memory store.

What is retrograde amnesia?

Retrograde amnesia means that a person is unable to remember events or information that they have learnt before the injury or illness; it will not, however, prevent them from learning new information or from storing new memories.

The severity of the amnesia will depend on the severity of the trauma that has been experienced; it may also be permanent or temporary or it may involve being unable to remember large amounts of information or perhaps just from one single event.

Retrograde amnesia is often caused by brain injuries, psychological trauma, illness and infection, poor nutrition and surgery which has gone wrong.

Symptoms of retrograde amnesia

An individual who experiences retrograde amnesia is likely to be subject to the following symptoms:

• Confusion: individuals may be confused about what has happened to them in the past and they may not be able to differentiate new information from something that has already happened to them
• False memories: when this occurs, individuals may believe that something has actually happened to them when it has not. False memories can be very distressing as they make individuals believe that they may have experienced something that they cannot remember or they may be completely convinced that something has happened when in fact, it has not
• Coordination problems: the area of the brain that is linked to long-term memory is also close to the area that controls coordination. This means that individuals who have problems with long-term memory are also likely to experience problems with coordination as well.

What is anterograde amnesia?

Anterograde amnesia occurs when an individual is unable to form new long-term memories after a brain injury, illness or whatever else has caused the amnesia to happen. Despite the lack of ability to form new memories, an individual does not lose their long-term memory and can usually remember everything that has occurred before the amnesia.

Like retrograde amnesia, the severity of the condition will depend very much on the severity of what has caused it. One of the most famous cases of amnesia was experienced by an individual who was simply referred to as HM. HM underwent brain surgery, after which his long-term memory remained intact but he was unable to form new memories or learn new skills or words. His case was studied up to his death in 2008.

You can learn more about HM online should you wish to research this case more thoroughly.

Symptoms of anterograde amnesia

The symptoms of anterograde amnesia include:

• Partial memory loss
• Confusion
• Being unable to remember familiar names and faces
• Difficulty in retaining new information
• Inability to remember places that were once familiar
• Some difficulty with coordination and occasional bodily tremors.