More than 5% of people over the age of 60 in the Western world are believed to suffer from dementia, about two-thirds of which is due to Alzheimer's disease.
Gene mutation may be to blame
Scientists in the United States and Europe reported in the journal Nature that they had found a gene coding mutation, A673T, that protects against both Alzheimer's and cognitive decline in elderly people who do not have the disease.
"This is a mutation in a gene that makes a protein that people have believed for a long time is involved in Alzheimers," geneticist Kari Stefansson of the Icelandic medical company deCODE genetics and lead author of the paper, told AFP. "What this mutation does is to make the protein less harmful."
If you had the rare mutation, you were between five and seven times less likely to develop the disease than the general population, said Stefansson - "a very strong protection".
Probing the genetic data of some 1 800 Icelanders, the scientists also found that people between the ages of 80 and 100 who did not have Alzheimer's disease but carried the mutation had much better cognitive function than those without it.
He added there had been a lot of research in the past two decades into manipulating the amyloid precursor protein, APP, to treat Alzheimer's - an incurable and progressive disease characterised by memory loss and dementia.
The disease involves an accumulation of amyloid plaques in the brain.
"This mutation could possibly represent a target for treatments to prevent Alzheimer's disease," a Nature press summary added.
(AFP, July 2012)
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