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     People with this "supergene" have a much higher chance of living to age 90 and beyond without developing dementia, the confused thinking and memory loss that so often plagues the oldest of the old, said Nir Barzilai, director of the Institute for Aging Research at the Albert Einstein College of Medicine in New York.

    Barzilai and his colleagues had found that centenarians were much more likely than others to have the gene variant, called CETP VV. People with the gene variant seemed to age slowly and were able to resist life-shortening ailments such as heart disease.

    To see whether the gene protected the brain too, the team studied 158 people of Ashkenazi (Eastern European) Jewish descent who were 95 or older. A brain function test found that seniors who had inherited the gene variant were twice as likely to have good brain function -- able to think clearly and remember new information -- as seniors without the gene.

    To see whether the gene protected against Alzheimer's, the team did a second study. A group of 124 Ashkenazi Jews aged 75 to 85 were followed for about eight years. Researchers noted any time a senior received a diagnosis of dementia. Participants who never developed dementia were five times more likely to have the favorable gene than those who did have dementia.

    The researchers don't know yet how the supergene protects people. Previous research has shown that the gene could affect the size of the lipoproteins in the blood that deposit or clear away cholesterol. People with the gene variant tend to be at less risk of clogged arteries, Barzilai said.

    The insights into how ageing affects the brain could lead to ways of protecting cognitive function in old age.

    If drugs could be developed which mimic the protective function of the CETP VV variant they could transform the quality of life of the ageing population.

    (Agencies)