Alzheimer's breakthrough could cut cases by a fifth, say gene scientists

Published on Sunday 6 September 2009 22:12

A "LEAP forward" in Alzheimer's research with the potential to cut rates of the disease by a fifth has been taken by gene scientists, it was revealed today.

Two international British and French-led teams together identified three new genes that are closely linked to the illness.

Cancelling out their effects could prevent almost 100,000 cases of "common" late-onset Alzheimer's a year in the UK.

Clues from the genes are already challenging previous assumptions about how the disease develops and pointing the way towards possible new therapies.

Professor Julie Williams, who led the British scientists, described the breakthrough in the journal Nature Genetics as "the biggest advance in Alzheimer's research in 15 years".

Rebecca Wood, chief executive of the Alzheimer's Research Trust charity which part-funded the UK-led study, said:

"At a time when we are yet to find ways of halting this devastating condition, this development is likely to spark off numerous new ideas, collaborations and more."

Alzheimer's is the most common form of dementia, affecting more than half the 700,000 people in the UK suffering from the condition.

In less than 20 years, almost a million people in the UK are expected to have dementia. This figure is forecast to soar to 1.7 million by 2051.

The three genes are the first to be associated with the common form of Alzheimer's since 1993, when a mutant form of a gene called APOE was found to account for about a quarter of cases.

Two, known as clusterin, or CLU, and PICALM, were identified by the UK team. The third, complement receptor 1, or CR1, was singled out by the French-led group.

Clusterin is known to protect the brain in a number of ways. Like APOE, it helps rid the brain of the potentially destructive amyloid protein. But it also dampens down damaging inflammation in the brain caused by an overactive immune response – a function it shares with CR1.

The scientists now believe inflammation may play a far more important role in Alzheimer's than was previously suspected.

Having certain versions of these genes increases the risk of Alzheimer's by 10 to 15 per cent.

The British-led study was the largest genetic investigation of Alzheimer's ever conducted and involved analysing the DNA from more than 16,000 individuals over two years. The scientists found common non-protective versions of the clusterin and PICALM genes might account for 19 per cent of disease cases.

Professor Williams, from the Medical Research Council Centre for Neuropsychiatric Genetics and Genomics at the University of Cardiff, said: "This combination of discoveries forms an important breakthrough in the current impetus to discover the causes of Alzheimer's disease.

"If we were able to remove the detrimental effects of these genes through treatments, we could reduce the proportion of people developing Alzheimer's by 20 per cent.

"In the UK alone this would prevent just under 100,000 people developing the disease."

Dr Susanne Sorensen, head of research at the Alzheimer's Society charity, said: "These discoveries will enable scientists to follow new avenues as they piece together the causes of Alzheimer's disease – likely to be a mixture of genes, lifestyle and life events. It could also lead to new drug treatments."