Introduction

What is dementia?

Dementia is the gradual and progressive loss of the powers of the brain. The most common cause is Alzheimer’s disease. Other types of dementia are vascular dementias (including multi infarct dementia), alcohol-related dementias, Lewy body dementia and Pick’s disease.

These diseases damage and kill brain cells, which is what causes the symptoms associated with dementia.

Gradually, the person with dementia begins to lose the ability to do things. Often it affects memory first. The person may become confused about where he or she is, what day it is and who people are. He or she will gradually lose the ability to think, reason, and take decisions. Everyday tasks become more and more difficult. His or her personality may change. As the illness progresses, the person will become increasingly reliant on others.

It is important to remember that every person with dementia is different. How the illness affects someone will depend on which areas of the brain are damaged.
With dementia, a person will become gradually less and less able, needing more help to cope with daily living. Eventually he or she will be unable to manage even basic tasks like eating, dressing and going to the toilet. But this will not happen suddenly; the illness can last many years.

There is no cure for dementia, and treatment is limited.

What causes dementia?

It is not certain what causes Alzheimer’s disease (the most common type of dementia). There are a number of changes which happen in the brain of someone with Alzheimer's disease. Deposits (called ‘plaques’) form, made up of an abnormal protein called beta amyloid; these lead to the death of brain cells. Meanwhile, inside brain cells, a protein called tau, forms abnormal tangles, damaging the cells. Plaques and tangles can be found in a normal ageing brain but are more pronounced in Alzheimer’s disease.

Vascular dementia (the second most common type of dementia) is caused by problems with the supply of blood to, or within, the brain. Blood vessels may be damaged or arteries become blocked, causing the death of brain tissue. There are different types of vascular dementia including: multi-infarct dementia - the cumulative effect of a series of small strokes - and single-infarct dementia where one stroke does enough damage to cause dementia.

Some people have mixed dementia - both Alzheimer’s disease and vascular dementia.

Alzheimer's disease and vascular dementia between them make up about 75% of cases of dementia, and much of the research on risk factors for dementia relate to these diseases. However, there are also many other types of dementia, including:

• Lewy body dementia, in which brain cells are damaged in a similar way to Parkinson’s disease but in a different part of the brain
• alcohol-related dementias, including Korsakoff's psychosis in which excessive alcohol consumption causes severe deficiency of vitamin B1, damaging areas in the middle of the brain, resulting in severe short-term memory loss
• frontal lobe dementia or Pick’s disease, in which specific areas of the brain (the frontal and temporal lobes) are damaged, causing personality and behaviour change, but not usually affecting memory until later in the illness.

Who is affected?

Dementia is an illness, not a normal part of growing older. Even at a very advanced age, most people do not have dementia. However, it is more common in older people. It affects about 2% of people aged 65 to 70, 5% of people aged 70 to 80, about 20% over 80 and 33% over 90. It can also affect people in their 40s or 50s or even younger, although this is rarer. This is called early onset dementia because it affects people at a relatively young age.

Dementia also affects those around the person with dementia. Families and carers have to provide increasing support and care as the person with dementia loses the ability to do everyday things.

Why is dementia important?

Dementia is a major public health issue in Scotland. It is the fourth biggest killer after heart disease, strokes and cancer. It is most common among older people, and as life expectancy increases, there will be more older people and so more people with dementia. By 2029 there will be 109,000 people with dementia in Scotland, up from 64,000 today. This has significant implications, not only for the individuals affected by the illness and their families and carers, but for the costs of providing the health and social care services they will need.

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Useful links:

Information about dementia
Dementia factsheet - some facts and figures