They have found that the part of the brain responsible for memory 'shrinks' 10 times faster in Alzheimer's sufferers than in healthy people. Dr Kim Jobst, of the Department of Pharmacology at Oxford University, said the findings suggest that the disease is caused by 'an event that has a catastrophic effect on the medial temporal lobe', causing it to degenerate.
More than 500,000 people suffer from Alzheimer's, which results in memory loss, dementia, and an inability to look after oneself. The disease presents a growing burden for carers and the health service as the number of older people in the population increases. Its cause is not known and there is some debate about whether or not it is an age-dependent disease, and an inevitable consequence of ageing.
A number of theories have been put forward as to its cause and most focus on biochemical changes in the brain which lead to damage and degeneration of certain areas.
Some researchers have linked an excess of aluminium with the disease; others blame a build-up of protein 'plaques', or the development of nerve 'tangles'.
Dr Jobst, who is clinical director of the Optima Project examining memory and ageing at Oxford, said that other factors had also been implicated, although these were 'less popular'. They include inflammation in the brain, blood vessel damage and interruption of blood supply, and a possible link with some type of steroids. These were all 'possible triggers' for the disease, Dr Jobst said.
'They may set off a whole series of reactions in a brain cell which spread like wildfire, leading to this excessive shrinkage.'
Dr Jobst and his team compared brain scans of 20 people suffering from Alzheimer's with those from 47 healthy, ageing controls, every year for four years. According to the report in tomorrow's issue of the Lancet, the scientists found that in normal ageing, the medial temporal lobe gets thinner by about 1.5 per cent every year. In Alzheimer patients, it shrinks at 10 times this rate, 15 per cent a year.
The findings prompted three questions, Dr Jobst said: 'Why is the medial temporal lobe so vulnerable; can the trigger for the catastrophic event be identified; and can agents be found to modify the event or protect neurons (nerve cells) from it, and so prevent the disease from evolving.'
A report in the British Medical Journal says that the drug tacrine, which has been widely promoted for Alzheimer's disease, appears to have no benefits, according to a small trial over nine months in 53 people with Alzheimer's.Reuse content