Memory problems

Memory is easily affected by brain injury because there are several structures within the brain that are involved in memory, and injury to any of these parts can impair memory performance. As remembering involves the stages of taking in information, storing it adequately and retrieving it when needed, injury to those parts of the brain responsible for these stages can lead to poor memory.

It is sometimes said that the reason people with memory impairment do not remember is because they are protecting themselves from some emotional shock or trauma, and that their memory problem can be cured by hypnosis or psychotherapy, or even by another shock of some kind. While it is true that some people become amnesic for ‘psychological’ reasons (and most films, plays and fictional books about memory loss seem to suggest such reasons), the fact is that in real life such people are rare. The majority of people with memory problems have these problems for a physical reason rather than a purely psychological reason: it is not that they will not remember, but that they cannot remember.

What is memory?

People often think of memory as a single skill. However, it is not one skill on its own but can instead be thought of as a number of skills working together. We can therefore classify memory in several ways, namely:

• the length of time information is stored

• the type of information to be remembered

• the stages involved in remembering

• the kind of remembering required

• whether the memories date from before or after the injury.

Each of these ways of classifying memory are discussed in turn below.

Length of storage

There are three main memory storage systems, each of which retains information for different lengths of time.

Sensory memory

This stores information for less than a quarter of a second. We use this memory system to make sense of moving pictures (visual sensory memory) and spoken language (auditory sensory memory). Most people with damage to this system would not think of themselves as having memory difficulties, and would present with perceptual or language problems.

Immediate or working memory

This second system holds information for a few seconds. We use this memory system when we need to ‘hold on’ to information for a short period of time, such as when we are looking up a new telephone number and need to remember the number for the time it takes to dial it. If the line is engaged or someone interrupts us, the information is lost from memory and we have to look it up again. Most people with brain injury do not have particular problems with this system.

Long-term memory

This system covers any length of time longer than a few seconds, ranging from about 10 seconds to decades. Although there are differences in memory for things that happened a few minutes ago and things that happened years ago, the difference is less clear cut than it is between sensory memory and immediate memory. Long-term memory can therefore mean different things to different people. We recommend using the following terms to distinguish between types of long-term memory:

• delayed memory when referring to the store of knowledge of events/information that was presented in the last few minutes;

• recent memory when referring to the store of knowledge accumulated in the last few days or weeks;

• remote memory when referring to the store of knowledge accumulated over several years.

Types of information to be remembered

Another way in which we can structure memory is in terms of the types of information that we are required to remember in everyday life. For instance, there are differences in the way that we remember general knowledge, the meaning of words, or social customs, and the way that we remember what we ate for dinner last night, or when we last paid our electricity bill. And both of these memory systems behave differently from the system we use when we are learning a skill such as riding a bicycle or playing the piano.

Remembering general knowledge, the meaning of words, social customs, and so forth, is referred to as semantic memory. One of the characteristics of semantic memory is that we do not, as a rule, remember exactly how or where we acquired the information, e.g. that elephants have trunks, and that breakfast is the first meal of the day. Rather, we gradually accumulate this information over time and can subsequently retrieve it when necessary. Sometimes people with brain injuries have problems with semantic memory, they may lose the knowledge of what an elephant is or what an elephant looks like. This is not typically seen, however, in most memory impaired people.

More common is the inability to remember personal experiences, called episodic memory. This includes things such as remembering what happened in our personal lives a few minutes or a few hours ago, to pass on a message as requested, or recall the name of the person to whom you were recently introduced. This system is most frequently affected in people with memory problems following brain injury.

Learning a new skill, such as riding a bicycle or playing the piano involves procedural memory. People improve with practice, but they do not need to remember how they actually learned the skill. They don’t even need to remember ever having done the task to learn the skill before. Thus, people with memory impairments can learn new skills or procedures without any conscious recollection of having carried out the task before.

Stages involved in remembering

The ability to remember something involves three stages: encoding, storage, and retrieval. Encoding means getting the information into memory in the first instance; storage means keeping the information in memory; and retrieval means extracting the information when you need it.

For example, suppose you wanted to learn the name of your new neighbour. You would first have to hear or see the name and register it – this is the encoding stage. You would then have to keep the name stored – this is the storage stage. You might do this by repeating the name to yourself, or thinking about it every now and again, or thinking of an association with the name, e.g. ‘Daphne’ might remind you of daffodils. Then, when you next meet your neighbour, you have to retrieve the name in order to greet him or her appropriately – this is the retrieval stage.

After a brain injury things can go wrong with any or all of these stages. Suggestions on how to help with improving encoding, storage and retrieval can be found later in this publication.

Types of remembering

Two of the main kinds of remembering are recall and recognition. Recall involves actively finding the information to be remembered. For example, if you have been asked to tell your mother the next time you see her, “Jean phoned and wants to come round on Saturday night”. If you remember the message accurately, you will have recalled the message itself. If you wrote the message down and then remembered to give the message to your mother, you will have recalled the need to pass on a message.

Sometimes we are not required to recall the information, but to recognise it when we see it or hear it. Most of us at some time have said something like, “I can’t remember the word/name/town but I would recognise it if I heard it”.

Most people with memory impairments find recall harder than recognition, although both systems are usually affected.

Another way of classifying the kind of remembering is to compare retrospective and prospective memory. Retrospective memory means remembering things you have seen, heard or done in the past, while prospective memory means remembering to do things such as taking your medication, feeding the dog or paying the electricity bill. The majority of people with memory impairments have problems with both retrospective and prospective memory.

Explicit and implicit memory are other terms for the kinds of remembering required. Explicit memory means that you can consciously recollect the information you want. For example, if I asked you to tell me where you went for your summer holiday last year and you were able to tell me, you would be using explicit memory. If, on the other hand, I asked you to explain how to ride a bicycle, or when and where you learned, you would probably find it difficult to explain or remember when and where you learned. You could, however, demonstrate how to ride a bicycle without much trouble, so you do have implicit memory of how to ride a bicycle.

Do the memories date from before or after the injury?

One of the questions frequently asked by relatives of people with memory impairments is, “why can she/he remember what happened 10 years ago but not what happened this morning?”, or a variation of this. The short answer is that old memories are stored differently in the brain from new memories.

Information from before the brain injury may be forgotten. For most people with brain injuries this gap in memory from before the injury will range from a few minutes to a few months. This type of memory loss from before the injury is known as retrograde amnesia. Memories laid down well before the period of retrograde amnesia are likely to be retained well.

Problems with memory for information learned after the injury are known as anterograde amnesia, and for most people these problems are likely to be a bigger nuisance and handicap than the memory loss that predates the injury.

Amnesia

Amnesia means literally ‘a lack of or an absence of memory’. In practice, however, nobody forgets absolutely everything, so amnesia refers to a failure to some part of the memory system(s). Sometimes the term ‘amnesia’ is used to mean any kind of memory disorder, and sometimes it is used to mean a very pure memory problem – i.e. when memory impairment is the only problem faced by an individual.

In the strictest sense, a person suffering from amnesia would show the following symptoms:

• a great difficulty in learning and remembering information of nearly all kinds;

• difficulty in remembering some information acquired before amnesia started;

• a normal immediate memory span (i.e. the person could repeat back a telephone number or short list of words if there was no delay or distraction);

• all other intellectual abilities (such as attention, language, perception, reasoning, judgement, etc) would be normal, or nearly normal.

In reality, of course, people suffering entirely and solely from a memory problem are relatively rare. It is much more common to find people who have a memory problem along with other problems, such as impaired reasoning or attention.

Whether the problem is ‘pure’ or not, people who suffer from amnesia are likely to:

• show normal or near-normal immediate memory (i.e. they can repeat back a telephone number immediately);

• have difficulty remembering things after a delay or distraction;

• have problems in learning new things;

• remember things that happened some time before their brain injury/illness better than they remember things that happened a short time before it;

• usually remember how to do things they were previously good at or had practised a great deal (e.g. playing the piano, swimming, driving a car);

• be helped by cues, such as giving the first letter of someone’s name.

What can we do to help people with memory problems?

People with brain injuries often achieve some recovery over a long period, and so memory problems may improve over time. It should be made clear, however, that no magic solutions exist to get memory back or to regain damaged memory. There is, to date, no drug or treatment or exercise which will restore or even improve memory significantly. However, we can still do things to help people cope with their loss of memory and to manage their day-to-day lives.

Taking in the information

If we are to remember efficiently, then we need to initially take in the information properly. Some people with brain injuries have problems doing this. It may be that they have language or perceptual problems that initially distorts the information they receive. Or sometimes too much information is offered all at once. Sometimes the information being given may be too complicated. To help avoid such situations, there are rules that can be followed:

• Simplify information that we expect the person with brain injury to remember. This applies particularly to the written word.

• Reduce the amount to be remembered (e.g. ask the person to remember one thing rather than three things).

• Make sure that the person with brain injury has understood the information by asking them to repeat it back or re-tell it in their own words.

• Try to get the person to link the information to something that they already know – that is, to make associations. For example, the name of the therapist might be better remembered if it is associated with a relative or film star of the same name.

• When assisting a person with brain injury to learn or remember something new, use the rule of ‘little and often’. Generally, it is better to work for a few minutes several times a day than for an hour once a day.

• If possible, encourage the person with brain injury to organise the information that is to be remembered. We know, for example, that if people are asked to remember a shopping list they remember more when they group the items into categories such as vegetables, dairy produce, cleaning materials, etc, than if they simply list the items randomly.

Storing the information

Most people forget new information rather rapidly over the first few days and then the rate of forgetting slows down. This is also true for people with memory problems, bearing in mind of course that in their case relatively little information gets stored in the first place. However, once we have helped to get the information in, we can help to keep it there by testing or persuading the person with memory impairments to rehearse or practise at intervals. The best way to help is to test the person immediately after seeing or hearing new information, then test again after a short delay, and again after a slightly longer delay. This process is continued, with the intervals being gradually lengthened. Such practise and rehearsal usually leads to better retention of information.

Retrieving the information

It is sometimes the case that, although you have learned something, you just cannot ‘reach’ it when you want it. This is more often the case for a person with memory problems, and if we can provide that person with a ‘hook’ in the form of a cue or prompt, she/he may then be able to access the correct memory. For example, providing the first letter of a name may well lead to the person remembering the whole name.

Perhaps all of us have experienced a situation where we recognise a face but cannot place the person. This is particularly likely to happen if the person is seen in a different place from that in which earlier meetings occurred. Retrieval is easier for most of us if the surroundings in which we are trying to remember something are the same as those in which we first learned it. People with memory impairments may find they remember better if they are in the same room with the same people who were there when something was first learned or experienced.

When trying to teach a person with memory impairments new information, we should therefore aim to teach that person to remember information in a number of different settings and social situations. Our aim should be to encourage learning in many different, everyday situations that are likely to be encountered in daily life. Learning must not be limited to a classroom or therapist’s office.

The mood or state of mind that we are in may also influence our ability to remember. We know that people who learn things when they are sober remember them better when they are sober. This may not seem surprising. However, it is also true that things learned when a person is drunk may be remembered better when that person is drunk again. Similarly, things learned when one is happy or sad are better recalled when the original emotion is experienced again. Consequently, when helping a person with memory impairments to remember, we should aim to teach him or her in a number of different moods.

Cues and prompts help with remembering as well, so sometimes supplying the first letter, sound, or part of a word can enable a person with memory impairments to find the information they want to remember. Sometimes it is possible to help people find their own prompts or cues by systematically going through letters of the alphabet (“Does the person’s name begin with A, B, C?” etc). Similarly, if a person has mislaid something, it often helps to go back to the last time they remember having the item, then ask them to go very carefully through all the actions that followed. In this way the location of the lost article may be recalled.

Which problems to tackle

It is sometimes possible to identify particular problems experienced by people with brain injuries. They and their relatives frequently report such problems as the following:

• forgetting what has been said

• difficulty learning a new skill

• repeating the same question over and overtelling the same story or joke over and over

• finding a television programme difficult to follow

• forgetting people’s names

• getting details mixed up

• forgetting a change in routine

• forgetting where things have been placed

Problems which cause most anxiety should be identified first. This might be approached by keeping a memory diary for a week or two. Record all the memory failures you notice and see which occur most frequently or which ones cause the greatest concerns.

If your relative with brain injury is attending therapy, you can arrange to talk to one or more of the therapists involved (these will usually include physiotherapists, occupational therapists, speech therapists and clinical psychologists). They may be able to offer valuable information that they have obtained as a result of their observations.

Deciding which particular problem(s) to tackle will depend on matters such as:

• future plans e.g. someone attending a day centre will have different needs from someone intending to return to university

• observations made by relatives, professional staff and friends

• the wishes of the person with memory impairments, although care must be taken here since sometimes a person with memory problems may be unrealistic about the severity of their problem(s) or the goals attainable, or may even deny the existence of a problem.

Deciding on the number of problems to tackle at once will depend on such things as the degree of intellectual difficulty, the level of awareness and motivation of the person with brain injury, and of course, the time available to relatives and helpers.

The information on this page was written by Professor Barbara A.Wilson, Honorary Clinical Neuropsychologist.

This information was last reviewed in 2025.