Some Technical Bits
Memory is an active process that is most unlike tape or video recording. What is remembered is influenced by the way in which it is encoded and this can be strongly affected by the environment and the situational demands put upon the person. For example, older people with uncorrected hearing difficulties spend so much mental energy concentrating on hearing what is being said that they find it difficult to remember as well as someone with good hearing. The storage of memory is not simply putting it away for later use. Studies show that in storage memories change, often becoming simpler but sometimes adding strange details. Retrieval is an active process also. The amount of help, cues or pressure that someone is under at the time can critically affect the success they have in bringing something to mind.
The importance of retrieval in helping learning was shown in an experiment in which people were asked to learn a list of words. Some were shown the list, tested, shown the list again, tested again etc for four cycles of show-test. The others were shown the list and then tested three times, shown the list again and tested three times once more. The second group learned the list as well as the first. This was despite having seen the list only twice when the others saw it four times.
Memory is not just one thing either. The classification of memory breaks it down into two major types. Declarative Memory is that of which we are fully aware. It has two subsets. Episodic Memory concerns events that have been personally experienced. It is the basis of most research into memory and is readily disrupted by brain damage. It’s impairment forms the classical amnesic syndrome.
Semantic Memory is general knowledge, and more. It is knowledge of the physical and social worlds, language, and the specialist knowledge we pick up in our education and professional training.
An example of the difference between Episodic and Semantic Memory would be the difference between knowing (remembering) the fact that Paris is the capital of France and recalling a visit to Paris that you made some time in the past.
Non-Declarative Memory represents a cluster of learning systems that are independent of episodic and semantic memory. Skills and habits can be learned with no awareness of learning or even that they have been learned. Often very well preserved in amnesia, eg riding a bike.
Classical Conditioning is a form of learning that requires no awareness. A doctor hid a drawing pin in his palm when he shook hands with an amnesic patient. Later the patient was reluctant to shake hands with this doctor despite declaring that they had never met before.
Prospective Memory has been poorly studied. It refers to the memory that one is supposed to be doing something at some time in the future. This is the sort of thing that our elderly friends and relations complain of commonly, going into a room and not remembering why they are there. It is closely allied to attention and it’s opposite, distraction.
A further distinction is made by professional psychologists between Short Term Memory which lasts a few seconds and Long Term Memory which holds information for any longer periods. Of course this is in complete contradiction with the more common usage which takes STM to be anything over the last few days, weeks or even months and LTM being material from the distant past. The explanation for this is that the poor memory for what was done yesterday or last week is a demonstation of the inability for memories to be laid down in the long term store. It is a form of Anterograde Amnesia (see below). The good memory for events from ten years ago or more is an example of memory stored before the injury, stroke or onset of dementia.
In terms of Memory Rehabilitation there are a few golden rules that we need to remember and put into practice all the time.
1. Memories from the distant past (before the brain injury or damage occurred) will generally be remembered better than more recent memories.
2. Helping someone remember with cues and prompts is much more likely to be successful than simply asking for a free, unaided recall. So, 'Did you have the porridge or the bacon and eggs for breakfast?' rather than 'what have you had to eat today?' Put briefly, recogntion beats recall.
3. Getting people to attend and possibly put a little effort in will help lay down a memory. Similarly, distracting the person will make remembering more difficult.
5. Many people with poor Short Term Memory can recall accurately over very short time spans. So, this means they will be able to repeat what you said, prefereably after a short delay. Each act of repetition (by the memory sufferer) acts as memory strengthener. See Spaced Retrieval
6. People can remember lots of things without being aware of them. Loss of memory typically involves Declarative Memory (above). So, if somebody says they have never been to XYZ Day Hospital but when they are there it is clear that they know their way around very well, it does not mean they are telling an untruth.
7. In progressive conditions information and skills that have been learned most recently can disappear first. So, we often see people forgetting their second language and reverting to the language of their childhood.
8. Memory for different sorts of things is thought to be held in different parts of the brain. So when memory for one aspect of knowledge is lost it does not necessarily mean everything goes. This is clearly the case with certain people who cannot recognise the faces of family members but can recognise the sound of their voices.
9. Losing your memory and being aware of it, being disoriented in the sense of not knowing what is going on, where you are nor the time, day or even year, is usually a profoundly frightening experience. Being confused is horrible and leaves one vulnerable to all sorts of anxieties.
10. Any atttempt at testing or assessing memory should be conducted with utmost sensitivity and regard for the possible humiliation of the person with a poor memory. Professionals should always ask themselves what will be the advantage to the memory suffer of such an assessment.
Amnesia
In conditions where there is a clear onset or event, like a brain injury or a CVA, then we differentiate between the loss of memory for events beforehand, called Retrograde Amnesia, and the difficulty in learning new material afterwards, termed Anterograde Amnesia. Typically in traumatic brain injury there is some retrograde amnesia for hours, days or rarely months prior to the insult. The ability to learn new material afterwards may improve with time and recovery so that some memories do get laid down. In AD there is difficulty in making new memories from the onset of the illness and an increasing loss of old memories as the disease progresses.
In pure amnesia it is only memory that is affected, and usually it is Episodic Memory that is most harmed. Intelligence and attention may be unaffected. There is also the retained ability to learn new skills (maybe in the absence of awareness of having learned them, non-declarative memory). There is however a profound inability to lay down new (declarative) memories combined with a loss of memory for events for some time prior to the event.
Alzheimer’s Disease (AD) is not pure and increasingly affects naming, praxis, social and ‘higher’ functions as well as memory. Attention begins to decline later.
Assessment
We should always ask ourselves why we are assessing someone. After all, most people can tell us if they have a poor memory or not; or their relatives can. Reasons for assessing somebody include the need to establish a diagnosis so that we are sure that the problem is truly serious rather than age-related and non-malignant. Or we may need to establish if the memory problem is as severe as the patient believes.
We may be involved in medico-legal proceedings when a court or insurers will be interested in establishing the exact status of someone’s memory.
Research and treatment evaluation are important reasons for assessing. If we do not know exactly how good or poor someone’s memory is beforehand we cannot claim success for our intervention no matter how brilliant we believe it to be.
Care planning is often a very good reason for memory assessments. A careful assessment of somebody’s memory can help us establish exactly where the problems lie and also where the remaining strengths are. Consequently, we may be less likely to put excessive demands upon somebody with eg. very poor short term memory by encouraging them to join a current affairs quiz team. Or, we may not insult somebody with a very good memory by limiting their activities to the undemanding. Occasionally we may discover people with unsuspected talents who are under stimulated, under occupied or plain bored.
As well as memory we should be assessing somebody’s physical health status to check for current illnesses, medication and their mood.
All three of these can play an important role in affecting memory for the worse.
Poly-pharmacy can be extremely destructive of older people’s cognitive abilities and reviews should take place regularly.
Four levels of assessment of memory.
1.Self report from the patient or a report from a carer or relative. This is very useful, easy to gain and has the advantage of being able to report change compared with past performance. The disadvantages are that self report sometimes is inaccurate. Not the least reason for this is that the person may simply not remember their memory deficits. Whilst relatives may over- or under- estimate memory difficulties for a variety of reasons usually their accounts are rather more accurate.
2.The very short tests such as the Mini Mental State Examination (MMSE), the Psycho-Geriatric Assessment Scales and the 6-CIT. All these attempt to gain a rough and quick (5 – 10 minutes) estimate of overall cognitive decline, so memory is only one part of them. They are easy to administer and can be given by staff with a requirement for only brief training.
3.More complicated tests that take about 20 – 30 minutes to administer. British examples are the Middlesex Elderly Assessment of Mental State (MEAMS) and the Cambridge Cognitive exam (CAMCOG) taken from the larger Cambridge Dementia Examination (CAMDEX). These tests sample in some detail areas of cognitive ability at around the level that somebody with suspected brain damage or dementia would begin to show deficits. Using them requires some training in administration and interpretation and is usually done by qualified staff.
The MEAMS for instance includes tests of:
| Orientation | Visual RecognitionMemory |
| Name Learning | Visual Perception |
| Naming | Word Fluency |
| Comprehension | Perseveration |
| Mental Arithmetic | Drawing |
The Addenbrookes Cognitive Exam (ACE-R), a new cognitive assessment that includes some memory items looks particularly promising. It falls somewhere between levels 2 and 3, and is free! It can be found in the useful document “SIGN 86. Management of Patients with Dementia” www.sign.ac.uk/pdf/sign86.pdf
4.Psychometric tests that are quite lengthy, some would say arduous, and can only be administered by someone with special training. Psychometric tests often compare the patient’s performance against that of a ‘normal’ group so they cover the whole range of abilities. Rather more so than the MEAMS and CAMCOG they are administered according to a very strict protocol but it can take anything between an hour and four hours of testing to fully assess a patient.