A report says that the onset of the disease is linked to the regeneration of connections between cells in the brain, which occurs naturally in everybody between the ages of 50 and 60.
In some people, the extra protein generated during this process disrupts brain cells, leading to their degeneration and the symptoms of Alzheimer's, which affects half a million people in Britain.
Dr Gareth Roberts, a neuro-anatomist at St Mary's Hospital Medical School, London, said yesterday that if the excess protein can be removed or prevented from building up, then the progression of the disease could be halted.
In the journal Neuroreport, Dr Roberts, and a team from St Mary's, the Charing Cross and Westminster Medical School, London, and Newcastle upon Tyne General Hospital, provide the first complete account of the development of Alzheimer's, relating brain chemistry and anatomy to age.
The three most significant factors in disease development are age; the presence of a particular protein known as beta amyloid pre-cursor protein (APP) in the brain cells of a sufferer; and the fact that the disease always starts in the same area of the brain - the medial temporal lobe - which is responsible for memory.
By examining brain tissue from 12 post-mortem samples taken from Alzheimer's sufferers and healthy individuals, the researchers discovered that this area contained far more APP than expected.
Alzheimer's accounts for 75 per cent of cases of dementia in people over 65. One in twenty people over the age of 65 suffers from Alzheimer's, rising to one in five over the age of 80.