INTRODUCTION TO ALZHEIMER'S DISEASE

What is Alzheimer's disease?

Between 50 and 70 percent of all people with dementia are suffering from Alzheimer's disease - a degenerative disease, which slowly and progressively destroys brain cells. It is named after Aloïs Alzheimer, a German neurologist, who in 1907 first described the symptoms as well as the neuropathological features of Alzheimer's disease such as plaques and tangles in the brain. The disease affects memory and mental functioning (e.g. thinking and speaking, etc.), but can also lead to other problems such as confusion, changes of mood and disorientation in time and space.

At first the symptoms such as difficulty with memory and loss of intellectual abilities may be so slight that they go unnoticed, both by the person concerned and his or her family and friends. However, as the disease progresses, the symptoms become more and more noticeable and start to interfere with routine work and social activities.

Practical difficulties with daily tasks such as dressing, washing and going to the toilet gradually become so severe that in time the person becomes totally dependent on others. Alzheimer's disease is neither infectious nor contagious. It is a terminal illness, which causes a general deterioration in health. However, the most common cause of death is pneumonia, because as the disease progresses the immune system deteriorates and there is weight loss, which increases the risk of throat and lung infections.

In the past, the term Alzheimer's disease tended to be used to refer to a form of pre-senile dementia as opposed to senile dementia. However, there is now a greater understanding that the disease affects people both under and over 65 years of age. Consequently, the disease is now often referred to as pre-senile or senile dementia of the Alzheimer type depending on the age of the person concerned.

Who is likely to be affected?

On the basis of comparisons of large groups of people with Alzheimer's disease with others who have not been affected, researchers suggest that there are a number of risk factors. This means that some people are more likely to suffer from the disease than others. However, it is unlikely that the disease could be traced to a single cause. It is more likely that a combination of factors lead to its development, with the importance of particular factors differing from one person to another.

Age

About one person out of twenty over the age of 65 suffers from Alzheimer's disease and less than one person in a thousand under the age of 65. However, it is important to note that although people do tend to become forgetful as times goes on, the vast majority of people over 80 stay mentally alert. This means that although the likelihood of suffering from Alzheimer's disease increases with age, old age does not itself cause the disease. Nevertheless, recent evidence suggests that age related problems such as arteriosclerosis may be important contributing factors. Also, as people are now living longer than in the past, the number of people with Alzheimer's disease and other forms of dementia will most probably increase.

Sex

Some studies have suggested that more women are affected by the disease than men at any one time. However, this can be misleading because women as a group live longer than men. This means that if men were to live as long as women and did not die of other illnesses, the number suffering from Alzheimer's disease would be about the same as that for women.

Genetic factors/heredity

In an extremely limited number of families Alzheimer's disease is a dominant genetic disorder. Members of such families inherit from one of their parents the part of the DNA (the genetic make-up), which causes the disease. On average, half the children of an affected parent will develop the disease. For the members of such families who develop Alzheimer's disease, the age of onset tends to be relatively low, usually between 35 and 60. The onset is fairly constant within the family. A link between chromosome 21 and Alzheimer's disease has been discovered. As Down's syndrome is caused by an anomaly in this chromosome, many children with Down's syndrome will develop Alzheimer's disease if they reach middle age, although they may not display the full range of symptoms.

Head injury

There is evidence to suggest that a person who has received a severe blow to the head may be at risk of developing Alzheimer's disease. This risk is higher if at the time of the injury the person is over 50, has a specific gene (apoE4) and lost consciousness just after the accident.

Other factors

There is no conclusive evidence to suggest that any particular group of people is more or less likely to develop Alzheimer's disease. Race, profession, geographical and socio-economic situation are not determinants of the disease. However, there is mounting evidence to suggest that people with a higher level of education are at less risk than those with a lower level of education.

Is Alzheimer's disease hereditary?

Alzheimer's disease is not usually hereditary. It is therefore not caused by the genes received from a person's parents. Even if several members of a family have in the past been diagnosed as having Alzheimer's disease, this does not mean that another member of the family will necessarily develop it, as the majority of cases of Alzheimer's disease are not genetic. However, as the disease is so common in the elderly, it is not unusual for two or more family members over the age of 65 to have it.

Whether or not there are other members of a family with Alzheimer's disease, everyone risks developing the disease at some time. However, it is now known that there is a gene, which can affect this risk. This gene is found on chromosome 19 and it is responsible for the production of a protein called apolipoprotein E (ApoE). There are three main types of this protein, one of which (ApoE4), although uncommon, makes it more likely that Alzheimer's disease will occur. However, it does not cause the disease, but merely increases the likelihood. For example, a person of 50, would have a 2 in 1,000 chance of developing Alzheimer's disease instead of the usual 1 in 1,000, but might never actually develop it. Only half of people with Alzheimer's disease have ApoE4 and not everyone with ApoE4 suffers from it.

Is there a test that can predict Alzheimer's disease?

It is inadvisable for people to waste their time or money on tests. There is no way to predict whether a particular person will develop the disease. It is possible to test for the ApoE4 gene, but such a test does not predict whether a particular person will develop Alzheimer's disease or not. It merely indicates that he or she is at greater risk. There are in fact people who have had the ApoE4 gene, lived well into old age and never developed Alzheimer's disease, just as there are people who did not have ApoE4, who did develop the disease. Therefore taking such a test carries the risk of unduly alarming or comforting somebody. Only in very rare families where Alzheimer's disease is a dominant genetic disorder unaffected relatives may take a predictive diagnostic test. The test must be preceded, accompanied and followed by comprehensive counselling.

Diagnosis of Alzheimer's disease
How is Alzheimer's disease diagnosed?

Alzheimer's disease is a form of dementia but is not necessarily caused by the same factors which cause other forms of dementia. However, despite a considerable amount of research, the actual cause of the disease remains unknown. There is no single test to determine whether someone has Alzheimer's disease. It is diagnosed by a process of elimination, as well as a careful examination of a person's physical and mental state, rather than by finding actual evidence of the disease.

Physical and mental state

A carer or relative may be asked to provide information about the person's behaviour, e.g. difficulties getting dressed, washing, handling finances, keeping appointments, travelling alone, managing at work and using household appliances. A neuropsychological assessment is usually carried out. This involves finding out about possible problems with memory, language, planning and attention. A simple test called the Mini-Mental State Examination is often used. This involves the person being asked to answer questions such as: What is the date? What city are we in? What is this called? (shown a watch). Another part of the test is to follow a series of simple instructions.

A number of tests may be carried out (e.g. blood and urine samples) in order to rule out the possibility of other illnesses which might explain the dementia syndrome or illnesses which might aggravate an already existing case of Alzheimer's disease. In addition to this, a few methods of brain imaging have been developed which produce images of the living brain, thereby revealing possible differences between the brains of people with Alzheimer's disease and those of non-affected individuals. These tests provide a risk-free and pain-free means of examining the brain of a living person. Although they cannot lead to a certain diagnosis of Alzheimer's disease, some doctors may use one or more of these techniques to give more weight to a diagnosis.

Methods of brain imaging
Magnetic Resonance Imaging

This permits an extremely detailed image of the brain's structure. When one image is placed over another, taken a few months' later, it is possible to see changes at an early stage in a certain part of the brain.

CT (Computed Tomography) Scanning

This measures the thickness of a part of the brain which becomes rapidly thinner in people with Alzheimer's disease.

SPECT (Single Photon Emission Computed Tomography) Scanning

This can be used to measure the flow of blood in the brain, which has been found to be reduced in people with Alzheimer's disease as a consequence of nerve cells not working properly.

PET (Positron Emission Tomography)

The use of this scanning technique is often limited to research settings. It can detect changes in the way the brain of someone with Alzheimer's disease functions. It can, for example, detect abnormal patterns of glucose usage by the brain.

What are the different kinds of diagnosis?

There are three possibilities for a diagnosis of Alzheimer's disease :

• possible
• probable
• certain Alzheimer's disease.

Possible Alzheimer's disease

A diagnosis of possible Alzheimer's disease is based on the observation of clinical symptoms and the deterioration of two or more cognitive functions (e.g. memory, language or thought) when a second illness is present which is not considered to be the cause of dementia, but makes the diagnosis of Alzheimer's disease less certain.

Probable Alzheimer's disease

The diagnosis is classed as probable on the basis of the same criteria used to diagnose possible Alzheimer's disease, but in the absence of a second illness.

Certain Alzheimer's disease

Identification of characteristic plaques and tangles in the brain is the only way to confirm with certainty the diagnosis of Alzheimer's disease. For this reason, the third diagnosis, that of certain Alzheimer's disease, can only be made by brain biopsy or after an autopsy has been carried out.

Should the person be informed of their diagnosis?

Nowadays more and more people with Alzheimer's disease are being informed of their diagnosis. This is perhaps due to a greater awareness of the disease. Some people might not want to be informed of the diagnosis. However, it is generally considered that everyone should have the right and be given the opportunity to decide whether they would rather know or waive this right. There are pros and cons involved in informing someone of their diagnosis. Also once the decision has been made to inform someone about their diagnosis the problem may arise of how to inform the person.

Pros and cons of telling the person

In many cases a diagnosis is made as a result of concern expressed by members of the family. Often the person with dementia is unaware or does not agree that they have a problem. They are therefore not interested in obtaining a diagnosis. Some might feel depressed about knowing or feel that they would have been happier not knowing. However, there are many advantages to knowing. When a person knows that they have Alzheimer's disease and understands what it involves, they can plan how to make the most of the remaining years of relative unimpaired mental functioning. They can also take an active role in planning their care, arrange who will care for them, make important financial decisions and even decide to participate in research or make the necessary arrangements to donate brain tissue after their death for research.

How to inform the person of the diagnosis

Some relatives and friends may find it difficult to approach the subject. Some people would prefer to be told privately on a one-to-one basis, whereas others might find it more reassuring to be told in the presence of their family, who could give them moral and emotional support. Another possibility is to arrange for the person's doctor to tell them. It might help to arrange to go to the doctor together or for the person to go alone. The doctor could then answer any questions that either the carer and/or the person with dementia might have. The way the diagnosis is explained will depend on the person's ability to understand. Some people might understand an explanation of what the disease is, how it tends to progress and the consequences for daily living, whereas others might only be able to grasp that they have a disease which involves the loss of memory. Once informed, they may need support to come to terms with feelings of anger, self-blame, fear and depression. Some might be able to benefit from counselling and support groups, provided that the disease is not too far advanced.

Is there any treatment for Alzheimer's disease

As yet, there is no preventative or curative treatment for Alzheimer's disease. A number of drugs exist, which can help alleviate certain symptoms such as agitation, anxiety, depression, hallucinations, confusion and insomnia. Unfortunately, these drugs tend to be effective for a limited number of patients, only for a short period of time and may cause undesirable side effects. It is therefore generally considered advisable to avoid medication unless really necessary.

It has been found that patients suffering from Alzheimer's disease have reduced levels of acetylcholine - a neurotransmitter (chemical substance responsible for transmitting messages from one cell to another) which plays a role in memory processes.

Certain drugs have been introduced in some countries, which can inhibit the enzyme responsible for destroying acetylcholine. In some patients these drugs improve memory and concentration. There is additional evidence that they have the potential to slow down the progression of symptoms temporarily. But, there is no evidence that they halt or reverse the process of cell damage. Such drugs treat the symptoms, but do not cure the disease. As European countries have widely differing legislation, we recommend that you consult a specialist in all cases.

What kind of research has been carried out?

Carers are naturally always on the lookout for information about treatment. However, although there is as yet no curative treatment, there are numerous experiments underway, aimed at discovering new treatments, possible causes, protective factors and risk factors associated with Alzheimer's disease. As it is not possible to provide full details of all the research being or having been carried out, details are given below of just a few areas of research.

Aluminium

Aluminium can be found in tap water, antiperspirants, tea and indigestion tablets. Researchers have been studying the possible effects of aluminium in connection with Alzheimer's disease for over 30 years. However, although research is continuing, there is still no conclusive evidence for a causal link between aluminium and Alzheimer's disease.

Anti-inflammatory drugs

It has been observed that Alzheimer's disease is less prevalent in people suffering from rheumatoid arthritis. Such people tend to take anti-inflammatory drugs over a lengthy period of time. It is therefore suspected that these drugs might reduce the risk, delay onset and hinder development of the disease. Research is continuing.

Carers and caring

Research has been carried out into the problems and needs of carers, e.g. the kind of support needed, difficulties encountered in providing care, problems obtaining a diagnosis and making difficult decisions, stress and depression. Such research is extremely important if the appropriate support, advice and services are to be provided for carers.

Oestrogen

Studies have shown that women who took estrogen (a hormone) after their menopause, had a lower risk of getting Alzheimer's disease than those who did not. Another small scale study revealed that women who already had Alzheimer's disease and who took estrogen showed marked improvements in memory and attention which then diminished when it was withdrawn. Researchers are currently carrying out an in-depth, large-scale study into the effects of estrogen on Alzheimer's disease.

Genetics

Researchers have investigated genetic factors, which might lead to Alzheimer's disease (either a defect, which would directly cause the disease or an abnormality, which would increase the possibility of getting the disease). Abnormalities in 4 genes on the chromosomes 1, 14, 19 and 21 have been identified and further research is underway. Pharmaceutical drugs Extensive research is being carried out by pharmaceutical companies into drugs, which might slow down the progression of the disease or improve symptoms such as memory loss.

Smoking

Some European studies have found that in families with the inherited form of Alzheimer's disease, smoking cigarettes seems to protect them for a few years longer. However, Canadian research has indicated that heavy smokers had more than double the risk of developing Alzheimer's disease, whereas light smokers were at the same risk as non-smokers.