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Alzheimer’s disease

Dementia is a broad term for the deterioration of brain function which results in loss of memory, reduced language skills and behavioural and emotional problems. Alzheimer’s disease is the most common type of dementia – it accounts for more than half the estimated 500,000 to 700,000 cases in the UK.

Alzheimer’s disease is rare before the age of 60 but the risk of developing it increases with age. Around a quarter of people over 80 have the disease.

Brain function
When the brain is functioning normally, it exchanges signals from other parts of the body, and other parts of the brain, across the gaps (synapses) between nerve cells. These signals – in the form of countless electrical impulses – are essential for brain activity such as language and problem solving. They are also involved in controlling motor functions, such as instructing muscles when and how to work.

Alzheimer’s disease is the result of the destruction of nerve cells (neurons) in the brain. These nerve cells cannot be replaced, so a person with Alzheimer’s disease gets progressively worse as more cells are destroyed.

The onset of Alzheimer’s disease is often difficult to pinpoint, as it starts with forgetfulness and difficulty in finding the right word, which are, of course, common problems associated with ageing. In these early stages, the people closest to the person with Alzheimer’s disease may notice personality changes. For example, a previously cheerful person may become irritable and even aggressive. He or she may no longer be able to cope with the demands of a busy life.

As the disease progresses, memory loss, difficulty in completing simple tasks, and more overt personality changes, often combined with depression, become more evident. Mathematical and verbal skills decline, which mean that a person may no longer be able to read instructions or to count their change. Conversation can become empty and meaningless.

Sometimes people with Alzheimer’s may become paranoid believing, for example, that their carers are trying to harm or kill them or that their partner is being unfaithful. People with Alzheimer’s can also lose their sense of time and place – they may, for example, get dressed in the middle of night or wander off and get lost, even in once-familiar territory.

This can cause a great deal of stress and upset for the person’s carers and family who have, in effect, lost the person they once knew.

During the late stages of the disease, people with Alzheimer’s may become totally dependent on others for their care. Walking can become difficult, and he or she may be confined to bed. They may become incontinent, experience hallucina-tions and become increasingly unaware of their surroundings. It is at this stage that residential care, with round-the-clock nursing, is often considered.

The disease lasts on average about ten years, though the period of time between diagnosis and the person dying varies from three to 20 years. Often the cause of death in a person with Alzheimer’s is another illness, such as pneumonia, which becomes more common in people who are bedbound and therefore less resistant to infection.

What causes Alzheimer’s
Nerve signals travel across the synapses with the help of chemicals known as “neurotransmitters”, including one called acetylcholine. Doctors believe that nerve cell destruction causes a reduction in acetylcholine, leading to impaired transmission of nerve signals.

Other explanations of Alzheimer’s disease focus on areas of abnormal protein in the brain called “plaques” and “tangles”, the names reflecting what these abnormalities in the brain look like under the microscope.

The underlying cause of Alzheimer’s – what actually triggers the changes in the brain – is still not known. It is likely that no single factor is responsible, but rather that it is due to a variety of factors, which may differ from person to person. People whose parents or brothers and sisters develop the disease appear to be at greater risk of developing it themselves, so there may be a genetic component. However, no straightforward pattern of inheritance has been found.

It is known that head injury is a risk factor, and also that Alzheimer’s disease often affects people with Down’s syndrome.

Some researchers have suggested that people who exercise their brains (for example, doing crosswords and other mental agility exercises) are less likely to develop the disease. And Omega 3 fatty acids, contained in oily fish such as mackerel and salmon may, also help to prevent dementia. But there is no completely solid evidence to show how environmental factors influencethe chance of getting Alzheimer’s.

There is no single test for Alzheimer’s disease, and diagnosis depends in part on excluding other potential causes of dementia. These include vascular dementia (often known as multi-infarct dementia, or MID), dementia with Lewy bodies (DLB), frontotemporal dementia (including Pick’s disease), Parkinson’s disease, and alcohol-related dementia (Korsakoff’s syndrome).

If a GP suspects someone may have Alzheimer’s, he or she will try to confirm some of the symptoms, such as memory loss and verbal (speech) impairment. Physical examination and blood and urine tests may be carried out to help exclude other causes of confusion.

he or she may make a referral to a specialist (a neurologist, a care of the elderly physician or a psychiatrist) for more specialist tests. These may include the mini-mental state examination (MMSE), which is a series of questions and tests which investigate memory, language and mathematical skills.

Other investigations may include a brain scan, typically magnetic resonance imaging (MRI).

Some people may also be referred to a “memory clinic” specialising in mental state assessments.

Unfortunately, so far there is no cure for Alzheimer’s disease. However, the disease can be managed with drugs, other treatments and support from a range of services.

Drug treatment
Recently-available drugs called cholinesterase inhibitors are the first effective drug treatment for Alzheimer’s. In someone with Alzheimer’s, cholinesterase breaks down and destroys acetylcholine, the neurotransmitter chemical. Cholinesterase inhibitors help to prevent this breakdown and so promote a more plentiful supply of acetylcholine. There are three such drugs available: donepezil hydrohydrocholoride (Aricept), rivastigmine (Exelon) and galantamine (Reminyl). In people in the early to middle stages of the disease, these drugs may slow down the progression of symptoms.

A newer treatment called memantine (Ebixa) has recently been launched for people in the middle to late stages of Alzheimer’s. It is not fully understood how well this drug works in practice, and it may not work for everyone. As a new drug that has not been reviewed by the National Institute of Clinical Excellence, memantine may not be readily available on NHS prescription.

Sometimes anti-depressants are prescribed to help treat the depression that can be associated with Alzheimer’s disease.

Other treatments
There are psychological techniques for helping to cope with Alzheimer’s disease. These include techniques known as reality orientation, reminiscence therapy and validation therapy. Art and music therapies are also used, but their effectiveness is not proven.

Help and support
Help and support in terms of respite care (giving carers a break), social services and residential care is an important part of the overall care of someone with Alzheimer’s disease. Further help Alzheimer’s Society 0845 300 0336 http://www.alzheimers.org.uk Alzheimer’s Research Trust 01223 843899 http://www.alzheimers-research.co.uk proven.

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