Sam Elder, of Greymouth Junior High School, asks :-

What causes Alzheimers disease?

John Campbell, a medical researcher at Otago University's School of Medicine, responded.

Alzheimer's disease is a very serious illness which affects older people, 6 per cent of people over the age of 65, and 20 per cent of people over 80. It causes an increasing loss of memory, difficulty remembering the right words to use, and difficulty remembering who people are. The person affected can easily get lost and needs increasing care.

The brain is made up of millions of nerve cells which connect with each other and messages are passed from one to another when a special chemical crosses the gap.

In Alzheimer's disease there is a loss of nerve cells and processes in particular parts of the brain so there are fewer nerve cells and they make fewer connections. Also the cells tangle and senile plaques build up between cells. We do not yet know what causes these changes but four possibilities have been suggested: age; inherited factors; a type of viral infection or toxic chemicals.

We no longer think that Alzheimer's disease is just due to age because the great majority of old people have well preserved memory. A very small proportion of people appear to inherit Alzheimer's disease, probably due to a chemical defect. There is no evidence for an infectious cause. Aluminium has been suggested as a toxic poison but the evidence for this is not convincing.

Because there is no known cause or cure of Alzheimer's disease there is an immense amount of research effort presently being carried out.