DIAGNOSIS OF THE CONDITIONS THAT CAUSE DEMENTIA: CONFIRMING THE PRESENCE OF DEMENTIA

It has already been mentioned that dementia is separate from the acute confusional state caused by an intercurrent illness such as pneumonia, a urinary tract infection, or the side-effects of drugs. These conditions are usually marked by a sudden onset rather than by the more slow and gradual onset of dementia. Careful inquiry from a relative, friend, or other person who knows the person under investigation well will help determine this and also whether there are any other current medical problems that make an acute confusional state more likely. An example of the latter is the repeated bouts of pneumonia to which people with chronic bronchitis, particularly heavy smokers, are prone. There are, however, many other medical conditions that can be responsible and unravelling these is best left to a general practitioner or, if necessary, a doctor in hospital.

Mrs Smith

A woman of seventy-three was admitted to the casualty department of a hospital at three in the morning one bitterly cold January night. She was brought in by the police who had been alerted by her neighbours, in whose garden she had been found wandering in a confused and dishevelled state wearing nothing but a thin nightgown. Mrs Smith, as we will call the patient, lived alone and was too confused and muddled to be able to answer any of the doctors’ or the nurses’ questions. She had no close relatives but appeared to be a respected and active member of the local community. Like many people of her age she had been noted as becoming a little more forgetful on occasions, but nothing out of the ordinary.

The doctors examined her but were unable to find very much that was wrong. They therefore had to rely upon routine tests to try to discover the nature of her illness. An X-ray of her chest revealed that she had pneumonia even though there were no signs of this on stethoscope examination. In addition, testing her blood showed that the level of sugar was much higher than it should be. Mrs Smith was therefore considered to have diabetes and a chest infection.

The following morning the hospital managed to make contact with her next-door neighbours. They confirmed that they knew her quite well, and had noticed that for about a week she had been thirstier than usual. Otherwise, apart from seeming a little muddled the day before she was admitted to hospital, they had noticed nothing amiss.

This confirmed the impression of the hospital doctors that Mrs Smith had previously undiagnosed diabetes and that this was complicated by a chest infection. Both the diabetes and the pneumonia were sufficient cause for her to have become acutely confused and it didn’t appear, from what her neighbours had said, that she had a progressive dementing illness.

Treatment for her diabetes and her pneumonia resulted in a dramatic improvement and after a fortnight she was back home just as well as she had been before her admission to hospital.

It is important to realize that even a person with a long history of dementia may also be the subject of an acute confusional state, as they may also have an infection or other illness. This has to be considered when the person with dementia suddenly appears to get worse.

Mrs Jones

Mrs Jones had been looking after her father who had had Alzheimer’s disease for several years. He and her mother had lived in their own old people’s bungalow until she had died. Mrs Jones was consulting her doctor to seek some treatment for her father because he had become more agitated and aggressive during the last week. Their general practitioner, however, declined to prescribe any form of treatment until he had had the opportunity of examining Mrs Jones’s father, and he arranged to call later that day. When he examined him, he discovered that her father’s abdomen was much more swollen than it ought to have been and that it was tender and uncomfortable. It appeared that this was because the bladder was unable to drain its contents because of an obstruction caused by enlargement of the prostate gland, not uncommon in elderly men. The doctor therefore arranged for a catheter (a tube) to be inserted via the penis into the bladder, allowing it to drain. When he was relieved of the discomfort caused by his distended bladder, Mrs Jones’s father became his normal self again and did not require any form of medication for his disturbed behaviour.

It can be very difficult to be certain whether the apparent early signs of dementia are really abnormal or whether the person concerned just has more marked age-related memory loss than most other people. There is no definite cut-off point between the effects of normal ageing and the onset of dementia and it is probable that, even if there were, it would differ in different individuals. The only way to be certain is to compare a person’s intellectual ability with what he or she had been like in the past and unless there is a reliable estimate of this it can be very difficult.

For this reason many doctors prefer to observe the person with a suspected but not definite dementing illness over a period of time to see whether there is any further deterioration in intellectual ability of the sort that is typical of dementia. This will often mean that the person concerned will have to undergo careful memory-testing and assessments of other aspects of mental function — often undertaken by a psychologist. A lot of the tests are administered nowadays with the help of a computer which often makes them easier for the subject and more reliable for the psychologist. At the same time the doctor will need to have accurate information from a close relative or friend, if one exists, about any changes they have noticed in the person’s ability to cope with day to day life over the same period.

As well as investigating different aspects of memory function, such as memory for recent events, events that have happened many years ago, and speech memory, the tests may cover other areas including assessment of concentration, the ability to carry out simple calculations, the ability to draw or copy geometric shapes, and to identify simple objects, for example different types of coin held in the hand with the eyes closed. There are of course many other types of test of intellectual function and in general they help to show whether a wide variety of different aspects of mental functioning are affected, even though this has not been suspected in the day to day life of the person suffering from possible early dementia. If there is indeed evidence to confirm suspicion of an early dementia, the pattern of the abnormal function may indicate which of the underlying causes is most likely, although it will rarely pinpoint a specific condition.

For a person in whom the abnormal mental functioning is more florid and for whom the presence of dementia is unequivocal, the tests described above are often still necessary; they will help to determine the rate at which the disease is progressing if they are administered on more than one occasion over a period of time, and are also helpful in assessing the severity of the condition. Again, although some of the simple and short tests can be easily undertaken by a doctor or nurse, if it is necessary to use the more complicated tests these are usually best administered by a psychologist, whose training fits him to assess and advise about such matters.