Alzheimer's disease is rare in younger people but the risk of developing it increases with age. In the UK, about 8,000 people under 65 have Alzheimer's. About one in 10 people over 80 are affected.
What is Alzheimer's disease?
Alzheimer's disease is the most common type of dementia. Dementia is the term for the deterioration of brain function that results in loss of memory, reduced language skills, impaired reasoning and behavioural and emotional problems. An estimated 700,000 people in the UK have dementia; around 400,000 of these have Alzheimer's disease.
Alzheimer's disease starts with forgetfulness and difficulty in finding the right words. In these early stages of the disease, family or friends may notice changes in behaviour. For example, a previously cheerful person may become sad, withdrawn or angry. He or she may no longer be able to cope with the demands of a busy life, and become frustrated with memory loss.
As the disease progresses, memory loss gets worse and some people have difficulty in learning new skills. Changes in behaviour may become more obvious, with people saying or doing things that are out of character. Everyday tasks such as getting dressed, washing, cooking, travelling and handling money become difficult.
Disorientation is common. People with Alzheimer's can lose their sense of time and place - they may, for example, get dressed in the middle of the night or walk off and get lost. New surroundings and new people may be confusing. There will be difficulty recognising previously well-known family and friends.
Some people become depressed because they realise what is happening to them. But many people with Alzheimer's don't realise they are ill.
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 urinary incontinence may develop. It is at this stage that many people consider residential care, with round-the-clock nursing.
The symptoms of Alzheimer's disease can cause a great deal of stress and upset for the person's carers and family who feel they have lost the person they once knew.
The period of time between diagnosis and the person dying can be anything from 18 months to 15 years, but is usually seven to 10 years. Often the cause of death in a person with Alzheimer's is another illness, such as an infection, which become more common in people who are frail and less able to fight off infections.
What happens in the brain with Alzheimer's disease?
When the brain is working normally, signals in the form of electrical impulses travel along nerves to and from the body and other parts of the brain. They cross the gaps (synapses) between nerve cells (neurons). These signals are essential for brain activity such as language and problem solving. They are also involved in controlling movements by instructing muscles when to work.
Nerve signals travel across the synapses with the help of chemicals called neurotransmitters, including one called acetylcholine.
In Alzheimer's disease, the number of nerve cells in the brain gradually reduces and the brain shrinks. These nerve cells can't be replaced, so a person with Alzheimer's disease gets progressively worse as more cells are destroyed.
Doctors believe that nerve cell destruction causes a reduction in acetylcholine, leading to impaired transmission of nerve signals.
The damage to the brain can be seen under a microscope. Brains affected by Alzheimer's disease have areas of plaques partly made up of dead nerve cells. The dead nerve cells contain tangles of an abnormal protein. These names reflect what these abnormalities in the brain look like under the microscope.
Why do people get Alzheimer's disease?
Doctors don't know why some people get Alzheimer's disease and other people don't. It is likely that no single factor causes it, but rather that it's due to a variety of factors that differ from person to person.
In about five to 10 percent of people, Alzheimer's disease is inherited.
There are also some genetic risk factors - particular brain characteristics that you may inherit - that make you more likely to get Alzheimer's, but do not mean that you definitely will. About half of people with Alzheimer's disease have parents or brothers and sisters who have it.
Other factors that make you more likely to develop Alzheimer's include previous head injury, low level of education, high blood pressure and heart disease. People with Down's syndrome may develop Alzheimer's disease in their 30s or 40s.
Various lifestyle and environmental factors have been linked with Alzheimer's disease. Some researchers have suggested that people who keep their brains active, for example, doing crosswords are less likely to develop the disease. Eating a healthy diet with enough omega 3 fatty acids, contained in oily fish such as mackerel and salmon, may help to prevent dementia. Staying physically active may also reduce the risk of developing the disease. However, more research is needed in this area.
There is no single test for Alzheimer's disease. 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 done to help exclude other causes of memory and intellectual problems or different types 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) and alcohol-related dementia (Korsakoff's syndrome).
The GP will probably make a referral to a specialist (a neurologist, a care of the elderly physician, a psychologist or a psychiatrist) for specialist tests. These may include the mini-mental state examination (MMSE), 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 will be referred to a "memory clinic" that specialises in diagnosing conditions like Alzheimer's.
So far there is no cure for Alzheimer's disease. However, drugs can help to slow down the progression or relieve some symptoms and delay the need for residential care. Other therapies and support are available.
A type of drug called cholinesterase inhibitors are used for people with moderate Alzheimer's disease. They work by reducing the breakdown of the neurotransmitter acetylcholine, levels of which are low in Alzheimer's. There are three such drugs available: donepezil (Aricept), rivastigmine (Exelon) and galantamine (Reminyl). In people in the middle stages of the disease, these drugs may slow down the progression of symptoms. These drugs need to be prescribed by a specialist in dementia.
Another drug, memantine (Ebixa), was launched for people in the late stages of Alzheimer's. There is not enough evidence to show that this drug is effective, and the National Institute for Health and Clinical Excellence (NICE) recommends that doctors do not prescribe it. Memantine may be available for some people who are taking part in a clinical trial.
Sometimes anti-depressant medicines are prescribed to help treat the depression that can be associated with Alzheimer's disease. Some people may benefit from anti-psychotic medicines (tranquillisers), which have a calming effect, to reduce behavioural problems of Alzheimer's such as aggression.
Various techniques, called person-centred treatments, may help people to cope with Alzheimer's disease:
behaviour management, where carers change behaviour by altering the triggers or consequences of the behaviour, can be used to reduce depression
reality orientation therapy, where a trained practitioner continually reminds the person of time, place and people, to keep him or her in the "here and now" - there is some evidence that this may delay the need for nursing care
Physical activity, conversation, mental stimulation and recreational activities can all help to improve life for people with Alzheimer's.
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.