Alzheimer's disease


Updated July 2006

A progressive deterioration in mental ability due to degeneration of brain tissue.

The term ‘dementia’ refers to a range of symptoms commonly found in people with brain diseases which result in the damage and loss of brain cells. Losing brain cells over time is a natural process, but with illnesses leading to dementia this occurs at a much faster rate and results in the person's brain not functioning in a normal manner. It was estimated in a global prevalence study that in 2005, 24.3 million people have dementia with one new case every 7 seconds.[see reference 1] Between 50 and 70 per cent of all people with dementia are suffering from Alzheimer’s disease - a degenerative disease, which slowly and progressively destroys brain cells.[see reference 2]

Prevalence rates of dementia in Europe by age and sex[see reference 3]
Age Group Male (%) Female (%)
30-59
0.16 0.09
60-64
1.58 0.47
65-69
2.17 1.10
70-74
4.61 3.86
75-79
5.04 6.67
80-84
12.12 13.50
85-89
18.45 22.76
90-94
32.1 32.25
95-99 31.58 36.0

It is normal to become mildly forgetful with increasing age, but severe impairment of short-term memory may be a sign of Alzheimer’s disease. It is more common in those over 65 and sometimes runs in families. In this disorder, brain cells gradually degenerate and deposits of an abnormal protein build up in the brain. As a result, the brain tissue shrinks and there is a progressive loss of mental abilities, known as dementia.

Alzheimer’s disease is the most common cause of dementia. The underlying cause of the tissue destruction is unknown, although genetic factors may be involved. Evidence is emerging that vascular risk factors (smoking, high blood pressure, raised cholesterol) may be implicated in the aetiology of Alzheimer's disease.

The first symptom of Alzheimer’s disease is usually forgetfulness. The normal deterioration of memory that occurs in old age becomes much more severe and begins to affect intellectual ability.

Memory loss is eventually accompanied by other symptoms, which may include:

  • poor concentration
  • difficulty in understanding written and spoken language
  • wandering and getting lost even in familiar surroundings
In the early stages of the disease, people are usually aware that they have become more forgetful. This may lead to depression and anxiety.

Over a longer period, the existing symptoms may get worse and additional symptoms may develop. These may include:
  • slow movements and unsteadiness when walking
  • rapid mood swings from happiness to tearfulness
  • personality changes, aggression and feelings of persecution
  • sometimes people find it difficult to sleep and become restless at night
  • weight loss due to reduced food intake
  • continence problems
There is no cure for Alzheimer’s disease, but drugs may slow the loss of mental function in mild to moderate cases. Eventually full time care may be necessary whether at home or in a nursing home. People caring for a person who has Alzheimer’s disease need practical and emotional support, especially if the affected person starts to become hostile and aggressive.

Support groups can help a person to cope with caring for an older relative with the disease. Most people with Alzheimer’s disease survive for up to 10 years from the time of diagnosis. Given that vascular risk factors may contribute to the aetiology of Alzheimer's, treatment of these in conjunction with other therapies may be of benefit.

References:
[1] Ferri C P et al (17 December 2005 - 6 January 2006) Global prevalence of dementia: a Delphi consensus study. The Lancet 366(9503): 2112-2117.
[2] Alzheimer Europe - What is Alzheimer's disease?
[3] Hofman A et al (1991) The prevalence of dementia in Europe: A collaborative study of 1980-1990 findings. International Journal of Epidemiology 20(3): 736-748.

Further information:

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