Studying hard and spending a long time in education can help protect people from the worst ravages of Alzheimer's in old age, medical researchers have found.

A survey of 130 elderly Catholic clergy suffering from the disease, which causes traumatic loss of memory and total mental decline, showed a link between the amount of time spent in education and the ability to cope with the impact of the disorder.

Scientists at the Rush Presbyterian-St Luke's Medical Centre in Chicago tested the patients to measure their ability to memorise information and pick up everyday objects. After death, their brains were measured for 'amyloid plaques', groups of proteins that kill brain cells and cause the disease.

Patients who spent longer in education generally performed better, regardless of the number of amyloid plaques in their brains. Though 90 percent had gone to further education, their experience varied from a year of undergraduate study to long periods doing complex research.

Researchers said the findings would help in developing preventive strategies for people that would try and keep their minds active as they got older and so delay the onset of dementia diseases. But they also said further research into why education helped to counter the disease could also produce future drugs to try and cure it.

'The major implications are for strategies to prevent disease,' said Dr David Bennett, director of the centre. 'However, it is possible to develop drugs that could help the brain cope with the burden of pathology if we understood the mechanisms at work here.'

Researchers at Britain's Alzheimer's Society welcomed the news and said it was possible that keeping mentally active in other ways could also help. 'It is like a use it or lose it strategy,' said Dr Richard Harvey, the society's director of research.

It is believed that education and studying could keep the nerve synapses in the brain busy and 'fit' in the same way as exercise keeps muscles in the rest of the body healthy. Harvey said that, while much research was needed, he recommended that keeping mentally active was important: 'For young people it could show that staying on in education actually could just make them less susceptible to Alzheimer's in old age.'

Previous studies have shown a link between other forms of mental activity and warding off brain disease. Last month York scientists showed that elderly people who engaged in pursuits like dancing the tango or playing chess or the piano were 75 per cent less likely to develop Alzheimer's or dementia. Some scientists now even recommend 'brain exercise' for people in their thirties as a way of minimising the chances of developing the disease.

As the population of the West becomes older, diseases like Alzheimer's are becoming a larger problem. There are about 750,000 sufferers in Britain, but the number is expected to rise to 1.5 million by the middle of the century.

Alzheimer's Society: www.alzheimers.org.uk