Alzheimer's gene!

Alzheimer's gene not active till old age

8th January 2007

Australian scientists have discovered that a gene which can cause Alzheimer's disease kicks in only in old age.

The findings confirm the notorious gene, called APOE4, has nothing to do with mental declines that are sometimes seen earlier in life.

Melbourne researchers studied 6,560 people aged 20 to 64, testing the skills most affected by the degenerative disorder - language, memory and reaction time.

The Canberra and Queanbeyan residents were tested every four years over 20 years to pick up early signs of the disease.

The study, published in the US journal Neuropsychology, found general decline over the years, but nothing differentiating the gene carriers - 27 per cent of the sample - from non-carriers.

Lead author Anthony Jorm, from the University of Melbourne, concluded that people with the gene have the same core mental functions as other people their age throughout most of adult life.

The work may help rule out the possibility of very early Alzheimer's as the cause of the declines among carriers before they reach old age, Prof Jorm said.

"Although some areas of cognitive decline begin from early adulthood onwards, this is not due, as some have speculated, to very early Alzheimer's changes in the brain," he wrote.

The APOE4 gene is the predominant risk factor for Alzheimer's, but researchers are unsure how it works.

They know it helps to transport cholesterol and may have a role in the nervous system.

AAP